# Trends in COVID-19 hospital outcomes in England before and after vaccine
introduction, a cohort study

PD Kirwan  Medical Research Council Biostatistics Unit, School of Clinical
Medicine, University of Cambridge, Cambridge, UK  A Charlett  UK Health
Security Agency, London, UK  P Birrell  UK Health Security Agency, London, UK
S Elgohari  UK Health Security Agency, London, UK  R Hope  UK Health Security
Agency, London, UK  S Mandal  UK Health Security Agency, London, UK  D De
Angelis  Medical Research Council Biostatistics Unit, School of Clinical
Medicine, University of Cambridge, Cambridge, UK  UK Health Security Agency,
London, UK  These authors jointly supervised this work.  AM Presanis  Medical
Research Council Biostatistics Unit, School of Clinical Medicine, University
of Cambridge, Cambridge, UK  These authors jointly supervised this work.

## Abstract

Widespread vaccination campaigns have changed the landscape for COVID-19,
vastly altering symptoms and reducing morbidity and mortality. We estimate
trends in mortality by month of admission and vaccination status among those
hospitalised with COVID-19 in England between March 2020 to September 2021,
controlling for demographic factors and hospital load.

Among 259,727 hospitalised COVID-19 cases, 51,948 (20.0%) experienced
mortality in hospital. Hospitalised fatality risk ranged from 40.3% (95%
confidence interval 39.4-41.3%) in March 2020 to 8.1% (7.2-9.0%) in June 2021.
Older individuals and those with multiple co-morbidities were more likely to
die or else experienced longer stays prior to discharge. Compared to
unvaccinated people, the hazard of hospitalised mortality was 0.71 (0.67-0.77)
with a first vaccine dose, and 0.56 (0.52-0.61) with a second vaccine dose.
Compared to hospital load at 0-20% of the busiest week, the hazard of
hospitalised mortality during periods of peak load (90-100%), was 1.23
(1.12-1.34).

The prognosis for people hospitalised with COVID-19 in England has varied
substantially throughout the pandemic and according to case-mix, vaccination,
and hospital load. Our estimates provide an indication for demands on hospital
resources, and the relationship between hospital burden and outcomes.

## Introduction

It is now well established that a segment of the population who acquire severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, the virus
responsible for coronavirus disease 2019 (COVID-19), in the community will
require hospitalisation, potential escalation to intensive care facilities,
and may die in hospital or soon after discharge. COVID-19 has been shown to
disproportionately impact older people and those with multiple comorbidities,
compared to younger, healthier individuals, and there is considerable evidence
that these factors heavily influence prognosis following hospital admission
for COVID-19 [1–4].

The extensive vaccination campaign in England during 2021 has dramatically
changed the outlook for COVID-19, lessening symptoms and reducing morbidity
and mortality [5,6]. Despite widespread and high levels of vaccination,
however, individuals continue to experience COVID-19 infection severe enough
to require hospitalisation. Several studies have previously examined COVID-19
hospitalised fatality risk (HFR) in England according to baseline demographic
factors [1–3,7–9] but there is little information about prognosis in the
current context of vaccination across the population and how this might be
related to hospital load.

We aimed to investigate trends in mortality within 90 days of hospitalisation
with COVID-19 among a national cohort of all people hospitalised with
community-onset COVID-19 in England and how these trends vary according to
vaccination status, hospital load, and other factors. We apply statistical
methods which account for competing outcomes to estimate absolute and relative
risks of hospitalised fatality, and lengths of stay in hospital by outcome,
and control for or assess the potential impact of different biases.

## Results

### Participant characteristics

Among 259,727 people with COVID-19 hospitalised between 15th March 2020 and
30th September 2021, a total of 51,948 (20.0%) died, 191,663 (73.8%) were
discharged and the remaining 16,116 (6.2%) remained in hospital at the date of
data extraction and/or were right-censored at 90 days (Table 1). Figure 1
presents weekly hospital admissions for COVID-19 over the study period, with
an indication of the first, second, and third waves. Figure 2 shows the
vaccination status of the study population between December 2020 and September
2021, by month of admission and age group, demonstrating the strong
correlation between age and vaccination during the second and third waves.

Table 1 presents patient characteristics for the study population. Compared to
all people with PCR-confirmed community-acquired COVID-19 infection, those
hospitalised for COVID-19 were older (48.4% aged over 65 vs. 10.0%), more
likely to be male (52.1% vs. 47.6%), and to reside in London (18.0% vs.
16.3%). A greater proportion of those hospitalised were of Black ethnicity
(5.9% vs 4.2%) and lived in an area of high deprivation (28.1% vs 23.6%),
compared to all those with community-acquired COVID-19. Comparative
information on comorbidity was not available, although 7.2% of those
hospitalised had a Charlson comorbidity index (CCI) score of 5 or more (Table
1) compared to 2.3% among a sample of 657,264 individuals 20 years and older
registered at English primary care practices in 2005 [10].

### Observed hospital outcomes

In unadjusted comparisons, older individuals experienced poorer outcomes
following hospital admission; almost half (46.5%) of those aged 85+ died in
hospital compared to just 0.5% of those aged 15-24. Similarly, males (as
compared to females), those living outside of London and the South West, and
those with an increased CCI score (compared to lower CCI) were more likely to
die in hospital (Supp. Table 1).

### Hospitalised case-fatality risk

Figure 3, panel a shows estimated HFR by month of hospital admission. HFR
decreased during the first wave of the pandemic from 40.3% (95% confidence
interval: 39.4-41.3%) in March 2020 to 12.3% (10.3-14.8%) in August 2020.
During the second wave HFR increased to a peak of 22.8% (22.5-23.2%) in
January 2021, although by March 2021 had halved to 10.5% (9.7-11.4%) and has
remained at or below 10% throughout subsequent months (Supp. Table 2).

In estimates of HFR by month and a single other covariate i.e. unadjusted for
all other covariates older individuals had increased HFR. In March 2020 HFR
was 1.4% (0.4-5.7%) among those aged 0-14, 22.3% (20.9-23.9%) for those aged
45-64 and 66.5% (64.4-68.7%) among those aged 85+ (Figure 4, panel a, Supp.
Table 3). Males tended to have greater HFR than females, although the extent
of this differed by month, being more evident in March 2020 (HFR of 43.7%
(42.5-44.9%) among males compared to 35.2% (33.8-36.6%) among females) than in
April 2021 (HFR of 8.6% (6.9-10.6%) among males compared to 8.9% (7.2-10.9%)
among females) (Supp. Figure 1, Supp. Table 4). HFR was lower for those
residing in London and the South West: in December 2020 HFR was 18.7%
(17.8-19.6%) in London and 17.5% (15.8-19.4%) in the South West, with a point
estimate above 22% in all other regions of England (Supp. Figure 3, Supp.
Table 6). Lastly, HFR was increased among those with a higher CCI; in December
2020 HFR was 6.7% (6.2-7.2%) among those with a CCI of 0, 22.4% (21.6-23.1%)
with a CCI of 1-2, 38.7% (37.3-40.2%) with a CCI of 3-4, and 47.3%
(45.3-49.4%) with a CCI of 5 or above. This association was seen throughout
the study period (Supp. Figure 4, Supp, Table 7).

During the initial months of the study those admitted to hospitals which were
experiencing higher load had a greater HFR as compared to those admitted to
hospitals with lower activity e.g. during March 2020, HFR was 44.9%
(39.6-50.9%) for hospitals at 90-100% of their peak load, compared to 38.8%
(36.6-41.0%) for hospitals at 0-20% of their peak load. This disparity
appeared to lessen during the summer months, but was seen again during autumn
of 2020, as admissions began rising. In November 2020, HFR was 23.6%
(21.1-26.4%) for hospitals at 90-100% of peak load, compared to 17.4%
(16.4-18.6%) for hospitals at 0-20% (Supp. Table 8).

### Length of stay

Figure 3, panel b shows estimated median lengths of stay until death or
discharge by month of hospital admission. Aside from the first two months of
the pandemic (March-April 2020), those with an eventual outcome of death had
longer stays in hospital compared to those who were discharged. The length of
stay prior to death and discharge followed approximately inverse trends:
whilst length of stay prior to discharge decreased throughout the first wave,
from 5.9 (5.8-6.0) days in March 2020 to 3.1 (2.9-3.3) days in August 2020,
length of stay prior to death increased from 5.6 (5.5-5.6) days to 9.9
(9.2-10.9) days.

During the second wave, lengths of stay prior to discharge initially
lengthened, peaking at 5.0 (5.0-5.1) days in December 2020, before falling to
2.7 (2.6-2.8) days by June 2021. Conversely, length of stay prior to death was
shortest in January, at 7.5 (7.5-7.6) days, and lengthened to 10.4 (10.1-10.8)
days by June 2021 (Supp. Table 2).

Examining the estimated lengths of stay for different subgroups (Figure 4,
panel b, Supp. Figures 1-5, Supp. Tables 3-8), similar patterns were observed
for males and females, although with less pronounced variation among males.
Length of stay prior to death estimates were imprecise for younger
individuals, due to the small number of events, but for age groups 45-64 and
above, the median length of stay prior to death decreased with increasing age.
Meanwhile older individuals had longer stays in hospital prior to discharge
compared to younger individuals; the median time to discharge among those aged
85+ ranged between 5.1-10.4 days, compared to between 0.8-2.4 days for those
aged 0-14 and 15-24 (Figure 4, panel b). Those with a higher CCI similarly
experienced shorter stays prior to death and longer stays prior to discharge;
in December 2020 those with a CCI above 5 remained in hospital for a median of
7.0 (6.8-7.2) days prior to death and 8.9 (8.7-9.0) days prior to discharge,
compared to 10.6 (10.3-11.0) days and 3.4 (3.3-3.4) days for those with a CCI
of 0. Hospitals experiencing higher load had similar lengths of stay until
discharge but shorter lengths of stay until death as compared to those with
lower activity.

### HFR by vaccination status

Table 2 shows HFR by vaccination status and age group. For all ages,
vaccination was associated with a reduced HFR, with significant reductions in
HFR among those hospitalised $\geq$21 days post first vaccine or $\geq$14 days
post second vaccine. The HFR for a double vaccinated adult aged 75-85 was
22.5% (20.4-24.8%), this compares to 38.6% (37.7-39.6%) for an unvaccinated
adult in the same age group and 25.3% (24.5-26.0%) for an unvaccinated adult
aged 65-75.

### Relative risks

Figure 5 presents hazard ratios for hospitalised fatality by month of
admission. Controlling for age group, region of residence, vaccination status,
sex, ethnicity, index of multiple deprivation (IMD) quintile, CCI and hospital
load, month of hospital admission remained a significant factor for the
prognosis of hospitalised individuals. Compared to June 2020, the hazard for
hospitalised fatality was increased during March to May 2020, September 2020
to February 2021, and June to September 2021 (Figure 5, Supp. Table 9).

Similarly, controlling for month of admission and the factors mentioned above,
vaccination status was a significant factor for prognosis following
hospitalisation. During January to September 2021, compared to the reference
category of unvaccinated, the hazard ratio for hospitalised fatality was 0.93
(0.89-0.98) for individuals hospitalised ¡21 days after first vaccination
dose, 0.71 (0.67-0.77) for individuals hospitalised $\geq$21 days after first
vaccination dose, and 0.56 (0.52-0.61) for individuals hospitalised $\geq$14
days after second vaccination dose (Figure 6, Supp. Table 10).

There was an increased hazard of hospitalised fatality for those of Asian
(1.19 (1.13-1.25)) but reduced for those of Black ethnicity (0.90 (0.84-0.97))
compared to reference category White. Males had a greater hazard compared to
females (1.28 (1.24-1.32)), and compared to a CCI of 0, those with a higher
burden of comorbidity had a greater hazard of hospitalised fatality (3.46
(3.27-3.67) for CCI of 5 and above). Those residing in more deprived quintiles
had greater hazards for hospitalised fatality (1.10 (1.05-1.15) for the most
deprived quintile) compared to a reference of least deprived (Supp. Figure 6,
Supp. Table 10).

Hazards were also elevated with increased hospital load, up to 1.23
(1.12-1.34) for load at 90-100% of the busiest week (compared to 0-20% load).

### Sensitivity to epidemic phase bias

Supplementary Figure 7 shows the outcome of the shift sensitivity analyses by
month of symptom onset, adjusted for the same covariates as above. The
greatest effect was observed for the March 2020 hazard ratio estimate, which
steadily reduced towards 1 following a shift of c=1, 2, 3 or 4 days. The
effect in other months was small, with the previously described monthly trends
persisting, although the slight reduction in hazard estimated for the most
recent month (September 2021) was no longer apparent.

## Discussion

People continue to experience hospitalisation for severe COVID-19, we aimed to
investigate how hospital prognosis and length of stay has changed with the
advent of vaccination and in the context of varying hospital pressures. We
examined absolute and relative risks of hospitalised fatality and lengths of
stay in hospital during the first year and a half of the COVID-19 pandemic in
England.

### Findings in context

We identified a number of studies exploring COVID-19 HFR in England according
to demographic factors [1–3,7,11–13]. In line with these epidemiological
studies, we found that people with community-acquired COVID-19 who became
hospitalised were older, more likely to be male, of Black ethnicity, and to
live in areas of high deprivation, as compared to everyone diagnosed with the
virus. Among those who were hospitalised, we estimated greater absolute
fatality risks for men and older individuals, and HFR also varied according to
ethnicity, month of admission, hospital load, and region. Lengths of stay in
hospital were similarly associated with demographic factors, with median
lengths of stay prior to death typically longer than those prior to discharge.
In relative risk analyses controlling for all measured confounders, baseline
comorbidity burden was the strongest predictor of death.

Prior to this study there was limited information available on COVID-19
outcomes at English hospitals by hospital load, although a recent King’s Fund
study concluded that a shortage of overnight and acute bed availability prior
to the pandemic had already put hospitals under increased strain [14]. In
Switzerland meanwhile, increased hospital load has been associated with poorer
outcomes for COVID-19, with an ICU occupancy of 70% or greater estimated to be
a tipping point at which outcomes became adversely affected [15].

Our estimates suggest a deterioration in survival as hospital load increases,
however, there are several potential biases which make this finding hard to
interpret. During periods of peak hospital load there is likely a modification
of an individual’s willingness to attend healthcare services for mild illness,
changes in admission criteria both to wards and intensive care units [16], and
individuals with milder disease may be selected for transfer from overloaded
hospitals to those with bed availability, due to the lower inherent risk. Each
of these factors may influence the case-mix at times of peak hospital demand.

There is now compelling evidence that vaccination reduces the number of
individuals being hospitalised [5] and the risk of mortality, regardless of
hospital admission [9,17]. We found reduced hospitalised fatality among
vaccinated individuals, with the reduction most clearly seen among older
individuals. For those aged 75 and over, vaccination reduced HFR to
approximately the risk of an unvaccinated individual aged 10 years younger. In
adjusted estimates, each additional vaccine dose reduced the hazard for
fatality by a significant margin, with a 42% (38-46%) estimated reduction in
the risk of death for double-vaccinated individuals. This is a slightly lower
reduction than for all community-acquired PCR-positive COVID-19 cases in
England, where a 51% (37-62%) reduced risk of death was estimated for
symptomatic individuals who had received a single vaccine [5]. This difference
may reflect the portion of hospitalised individuals who die from other causes,
or could be an indication of waning vaccine efficacy among our study
population.

After controlling for all measured covariates, including hospital load and
vaccination, we continued to estimate monthly variation in outcomes, with
apparent seasonal variation in hazards. Whilst seasonal patterns in
respiratory pathogens such as influenza and respiratory syncytial virus are
well-documented [18,19], a multitude of interlinked factors including changes
in national restrictions and the emergence of new variants may have influenced
these trends.

### Strengths and limitations

The use of high-quality hospital surveillance data linked to several other
comprehensive data sources is a strength of this study and enabled a broader
understanding of the factors influencing hospitalised fatality. For covariates
with varying levels of completeness we undertook sensitivity analyses to
confirm minimal effects on our estimates (e.g. indication of injury as a
factor for emergency care admission), however, there may have been other
unmeasured confounders for which we could not account. Using appropriate
statistical methods we adjusted for competing risks, and the use of a
relatively coarse monthly timescale likely limited the extent to which our
study was affected by epidemic phase bias [20]. Data linkage allowed for
deaths occurring shortly after discharge to be identified, almost a fifth of
all deaths in the study occurred within 14 days of discharge, suggesting
palliative discharge.

Data on hospital pathways following admission were unavailable. As such, we
were not able to subdivide the hospitalised population by severity of
infection and/or need of respiratory support, whether within or outside of
intensive care. Treatment data and changes in patient management were
similarly unmeasured in our dataset, although the use of therapeutic agents is
likely to have contributed to the reduction in hospital fatality risk,
particularly at the start of the pandemic [7,21].

The measure of hospital burden we used considered acute hospital admissions at
and around the time of admission as a proxy for bed occupancy. Whilst no
single accepted measure of hospital burden exists, overnight bed occupancy is
a widely used metric [14], and guidance on bed occupancy was issued to ICUs
(e.g. alterations in practice upon reaching 150% and 200% above pre-pandemic
baseline) [16]. A limitation of the bed occupancy measure is that it only
measures demand and not supply (i.e. staffing levels), or the extent of other
hospital pressures. Work to access and integrate measures of supply is
ongoing.

Lastly, this study did not consider the significant proportion of individuals
(up to 40%) who may have acquired COVID-19 nosocomially (in hospital).
Fatality risks and lengths of hospital stay for these individuals are
complicated by other conditions. Whilst not considered in our estimates,
researchers in Scotland have found similar effects of age, sex, and
comorbidity upon prognosis following nosocomial COVID-19 acquisition [22].

### Summary

Hospital outcomes and lengths of stay continue to vary according to case-mix,
vaccination, and changes in hospital load more than 18 months after the
pandemic began in England. One of the primary goals of the lockdown measures
implemented in England at various times since the start of the pandemic has
been to protect against hospitals becoming excessively overburdened. Even with
these measures in place, being admitted during a period of high hospital load
was correlated with poorer outcomes. Meanwhile, vaccinated individuals
admitted to hospital for COVID-19 had a significantly reduced risk of
mortality.

Outcomes following hospitalisation with COVID-19 should continue to be
monitored, particularly with the emergence of new variants. The datasets and
methods we describe continue to be vital to estimate changes in severity,
providing an indication for demands on hospital resources, resulting effects
on waiting lists for elective procedures, and monitoring the relationship
between hospital burden and outcomes.

## Methods

### Study design and setting

A retrospective cohort study using competing risk regression to estimate
relative risks of severe outcomes. We consider data on hospital admissions in
England since the initial wave of COVID-19 in March 2020 until the end of
September 2021, with follow-up until 22nd November 2021.

### Participants

All individuals aged 15 years and older with community-acquired COVID-19
(defined as a positive test for COVID-19 within -14 to 1 days of hospital
admission), admitted to hospital in England for COVID-19 or another non-injury
related condition between 1st March 2020 and 30th September 2021 were included
(n=259,727). Hospital records with inconsistent date information (n=2) or
missing demographic information (n=302) were excluded.

### Data sources and outcomes

The United Kingdom Health Security Agency (UKHSA), alongside NHS England,
monitors infectious diseases in England. The NHS England Secondary Uses
Service (SUS) dataset contains well completed, accurate information on
hospitalisation for COVID-19 in England, along with identifiers to augment
these data through linkage to other routinely collected information.
Admissions are, however, only entered into the SUS dataset upon completion of
a hospital stay (i.e. at the point of discharge from hospital or death). So
the information in SUS data was supplemented with information on individuals
still in hospital though linkage to the Emergency Care Dataset for England
(ECDS), which promptly records all emergency care attendances and onwards
destinations (i.e. discharge home or admittance to hospital). Among those with
completed hospital episodes, 77% were admitted via emergency care.

Complete information on deaths was obtained through linkage to the UKHSA
deaths dataset, containing all dates of death for people with a positive
COVID-19 test. Date of vaccination (first and second dose, third doses were
not considered as only n=11 hospitalised case had received a third dose during
the follow-up period) was obtained through linkage to the UKHSA National
Immunisation Management Service (NIMS). Testing information both for
community-acquired COVID-19 infections identified through PCR testing on
arrival at hospital (Pillar 1) and PCR testing within the community (Pillar 2)
were obtained from the UKHSA Second Generation Surveillance System (SGSS). All
data were stored and analysed on UKHSA computers under agreed data governance
protocols.

### Covariates

Covariates in the linked dataset included vaccination status (unvaccinated,
¡21 days of first dose, $\geq$21 days after first dose, $\geq$14 days after
second dose), date of hospital admission (aggregated by month), age group,
region of residence (Government office region), Charlson Comorbidity Index
(CCI) [23], ethnicity, sex, index of multiple deprivation (IMD) quintile, and
measure of hospital load. The hospital load measure was defined as the number
of COVID-19 admissions at an NHS trust within the 7 days around admission (3
before, same day, and 3 after), as a proportion of the busiest 7-day period at
that trust. Hospital load was grouped into: 0-20%, 20-40%, 40-60%, 60-80%,
80-90%, and 90-100%. In relative risk analyses the two key exposure variables
considered were vaccination status and month of hospital admission.

### Representativeness

Data comprised all new admissions for COVID-19 reported in England. Numbers of
reported admissions were compared with the NHS weekly COVID-19 admissions data
[24] to ensure data were representative. Hospital-onset COVID-19 (i.e.
infection occurring in hospital) cases were excluded: those who acquired a
hospital-onset infection during the study period (n=208,851) tended to be
older and have longer lengths of stay than the community-onset cases
considered in this study, with a greater proportion remaining in hospital
post-90 days (Table 1). Hospital stays for these individuals may be influenced
by conditions other than COVID-19, as described by Bhattacharya et al [25].

### Bias

Data validation was undertaken between the linked datasets, we found no
systematic under-reporting or misreporting of person characteristics and
linked information was used to minimise missing data. Censored outcomes and
competing risks were explicitly accounted for by the choice of statistical
method.

We carried out a sensitivity analysis to assess the potential effect of
epidemic phase bias on the estimated hazard ratios in relative risk analyses
[20]. This bias is caused by conditioning on an observed date later than the
date of infection (see Supplementary Information for a full description),
therefore in the sensitivity analysis we conditioned on date of symptom onset,
which is nearer to date of infection than date of hospital admission. This
conditioning ensured that the sensitivity analysis targeted bias due to
epidemic phase, as opposed to any other factors which may influence time from
symptom onset to admission.

### Statistical methods

In our study, hospitalised individuals are at risk of more than one event
during the follow-up period i.e. they can die or be discharged. In this
competing risk context standard survival analysis may result in biased
estimates of the absolute and relative risks of hospitalised fatality,
particularly when one of the competing risk is large (e.g. discharges to
palliative care as a competing risk for death) [26]. Therefore, two
alternative, complementary, statistical analyses were undertaken (see
Supplementary Information for more details).

We used Aalen-Johansen cumulative incidence estimation to obtain estimates of
cumulative HFR and median lengths of stay in hospital for specific sub-sets of
the population, unadjusted for other factors [27]. Median lengths of stay were
the weighted median estimate with weighted ties. We used stratified Fine-Gray
competing risk regression with adjustment for confounders to estimate the
association of each risk factor with the cumulative incidence of mortality
within 90 days of hospitalisation with COVID-19 (we term this hospitalised
fatality). Fine-Gray regression models the proportional sub-distribution
hazard of hospitalised fatality derived from the cumulative incidence function
[28]. Stratification was used for confounders with non-proportional hazards
(see Supplementary Information).

### Censoring

To focus our analyses on outcomes following COVID-19 admission, a pragmatic
cut-off of 90 days from first positive specimen date was chosen and only those
hospital outcomes (death or discharge) occurring within this cut-off were
included. All records with outcomes occurring beyond 90 days (n=656) were
right-censored at 90 days, while individuals who remained in hospital at the
date of data extraction (n=15,460) were right-censored at the shorter of this
date or 90 days. To better account for palliative discharge, deaths occurring
within 14 days of discharge from hospital (n=9,933, 19.1% of all deaths
observed) were classified as deaths rather than discharges and the date of
death used as the outcome date. Linkage to the UKHSA deaths data enabled these
post-hospital discharge deaths to be identified.

### Model implementation

Statistical models were implemented using R version 4.1.1 (R Foundation for
Statistical Computing, Vienna, Austria) and the open-source packages survival
v. 3.2-12 [29], and matrixStats v. 0.60.0 [30].

### Ethics approval

This study does not contain patient identifiable data. Consent from
individuals involved in this study was not required. The mandatory
surveillance systems used in this study, NHS England Secondary Uses Service
(SUS), Emergency Care Dataset for England (ECDS), UKHSA deaths dataset, UKHSA
National Immunisation Management Service (NIMS), and UKHSA Second Generation
Surveillance System (SGSS), are approved by the Department of Health and
Social Care. Data were collected with permissions granted under Regulation 3
of The Health Service (Control of Patient Information) Regulations 2002, and
without explicit patient permission under Section 251 of the NHS Act 2006.

### Patient and public involvement

This study was a retrospective cohort analysis. The research question, design
and data collection were motivated by the response to an urgent public health
emergency. The surveillance data were collected by NHS England and the UK
Health Security Agency with permissions granted under Regulation 3 of The
Health Service (Control of Patient Information) Regulations 2002, and without
explicit patient permission under Section 251 of the NHS Act 2006. Although
patients were not directly involved in the study design, the experiences of
clinicians and public health officials interacting with patients informed the
design of the data collection.

### Dissemination to participants and related patient and public communities

UKHSA and the MRC Biostatistics Unit have public facing websites and Twitter
accounts @UKHSA and @MRC_BSU. UKHSA and the MRC Biostatistics Unit engage with
print and internet press, television, radio, news, and documentary programme
makers.

### Transparency statement

The lead author affirms that this manuscript is an honest, accurate, and
transparent account of the study being reported; that no important aspects of
the study have been omitted; and that any discrepancies from the study as
planned (and, if relevant, registered) have been explained.

### Data availability

The data used in this study are protected data. These data are not publicly
available because the information is personal or special category personal
data, and there is risk of ‘re-identification’ of data that has been
anonymised by data matching, inference or deductive disclosure.

Access to protected data is subject to robust governance protocols, where it
is lawful, ethical and safe to do so. Individuals and organisations wishing to
request access to data used in this study, from the NHS England Secondary Uses
Service (SUS), Emergency Care Dataset for England (ECDS), UKHSA deaths
dataset, UKHSA National Immunisation Management Service (NIMS), or UKHSA
Second Generation Surveillance System (SGSS) can make a request directly to
NHS Digital (https://digital.nhs.uk/services/data-access-request-service-dars)
or to UKHSA (https://www.gov.uk/government/publications/accessing-ukhsa-
protected-data). Access to protected data is always strictly controlled using
legally binding data sharing contracts.

Requests for underlying data cannot be granted by the authors because the data
were acquired under licence/data sharing agreement from NHS Digital and UKHSA,
for which conditions of use (and further use) apply.

The estimated or observed values underlying each figure can be found in the
Supplementary tables.

### Code availability

Code for the survival and matrixStats R packages is available from the
Comprehensive R Archive Network (https://cran.r-project.org/). R code written
to process the data, implement the statistical analysis, and produce the
figures and tables is available online [31].

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### Acknowledgements

We gratefully acknowledge all the clinicians, data reporters and individuals
whose data were used in this study, as well as all UK Health Security Agency
colleagues involved in the COVID-19 response. We thank Shaun Seaman and Tommy
Nyberg of the MRC Biostatistics Unit, Cambridge for their advice on epidemic
phase bias, Kevin Fong and Tristan Caulfield at University College London
Hospitals NHS Foundation Trust for discussion of the hospital load measure,
James Stimson and members of the UKHSA Joint Modelling Team for the discussion
and support of these analyses, and members of the UKHSA Immunisation Division
for support with data preparation and linkage.

This research is funded by the Medical Research Council (Unit programme number
MC_UU_00002/11, DDA, AMP); a grant from the MRC UKRI/DHSC NIHR COVID-19 rapid
response call (grant ref: MC_PC_19074, DDA, AMP); and the NIHR Health
Protection Research Unit in Behavioural Science and Evaluation (DDA, AMP).
This research is also funded by the Department of Health and Social Care using
UK Aid funding, managed by the NIHR (grant number PR-OD-1017-20006, DDA, AMP).
The funders had no influence on the methods, interpretation of results or
decision to submit.

### Authors’ contributions statement

PDK, PB, AMP, and DDA conceived the research study. AC, RH, SE, and SM
undertook data collection and dataset generation. PDK and AMP drafted the
manuscript and formatted and verified the datasets. PDK carried out the
analyses. AC, PB, SE, SM, RH, and DDA provided expert advice and critical
review of the manuscript prior to submission. The corresponding author attests
that all listed authors meet authorship criteria and that no others meeting
the criteria have been omitted.

### Competing interests statement

The authors declare no competing interests.

## Tables

Table 1: * Table 1: Characteristics of the study population compared with all people hospital-onset COVID-19 in England and all people with PCR-confirmed community-acquired COVID-19 in England. |  |  |  |  |
---|---|---|---|---|---
Characteristic |  | Study population
---
(hospitalised for
COVID-19 in
England)
| All people with
---
hospital-onset
COVID-19 in
England
| All people with
---
PCR-confirmed
community-
acquired COVID-
19 in England
|  | n (%) | n (%) | n (%)
Total | 259,727 (100%) | 208,851 (100%) | 6,616,231 (100%)
Age |  |  |
| 0-14 | 6650 (2.6%) | 2632 (1.3%) | 892,640 (13.5%)
| 15-24 | 8972 (3.5%) | 4417 (2.1%) | 1,265,595 (19.1%)
| 35-44 | 44,094 (17.0%) | 13728 (6.6%) | 2,242,751 (33.9%)
| 45-64 | 74,258 (28.6%) | 33,166 (15.9%) | 1,559,808 (23.6%)
| 65-74 | 42,307 (16.3%) | 36,466 (17.5%) | 301,356 (4.6%)
| 75-84 | 47,783 (18.4%) | 59,841 (28.7%) | 198,201 (3.0%)
| 85+ | 35,663 (13.7%) | 58,601 (28.1%) | 155,880 (2.4%)
Sex |  |  |
| Male | 135,419 (52.1%) | 108,518 (52.0%) | 3,151,711 (47.6%)
| Female | 124,308 (47.9%) | 100,333 (48.0%) | 3,464,520 (52.4%)
Ethnicity |  |  |
| White | 195,496 (75.3%) | 185,078 (88.6%) | 5,100,116 (77.1%)
| Asian | 32,191 (12.4%) | 9930 (4.8%) | 740,194 (11.2%)
| Black | 15,394 (5.9%) | 6376 (3.1%) | 278,773 (4.2%)
| Mixed/Other/Unknown | 16,646 (6.4%) | 7467 (3.6%) | 497,148 (7.5%)
Region of residence |  |  |
| London | 46,854 (18.0%) | 28,976 (13.9%) | 1,077,599 (16.3%)
| East Midlands | 22,571 (8.7%) | 18,721 (9.0%) | 586,513 (8.9%)
| East of England | 26,323 (10.1%) | 22,696 (10.9%) | 678,869 (10.3%)
| North East | 15,131 (5.8%) | 9403 (4.5%) | 376,600 (5.7%)
| North West | 43,017 (16.6%) | 42,130 (20.2%) | 1,056,012 (16.0%)
| South East | 32,740 (12.6%) | 28,785 (13.8%) | 887,116 (13.4%)
| South West | 17,391 (6.7%) | 12,854 (6.2%) | 496,411 (7.5%)
| West Midlands | 29,808 (11.5%) | 24,513 (11.7%) | 733,250 (11.1%)
| Yorkshire and Humber | 25,892 (10.0%) | 20,773 (9.9%) | 723,861 (10.9%)
Index of multiple deprivation |  |
| 1st quintile (most deprived) | 73,100 (28.1%) | 51,176 (24.5%) | 1,564,464 (23.6%)
| 2nd quintile | 59,754 (23.0%) | 44,886 (21.5%) | 1,440,534 (21.8%)
| 3rd quintile | 48,458 (18.7%) | 40,595 (19.4%) | 1,287,972 (19.5%)
| 4th quintile | 42,608 (16.4%) | 38,396 (18.4%) | 1,209,869 (18.3%)
| 5th quintile (least deprived) | 35,807 (13.8%) | 33,798 (16.2%) | 1,113,392 (16.8%)
Month of hospital admission |  |
| Mar-20 | 12,408 (4.8%) | 17,564 (8.4%) | 31,598 (0.5%)
| Apr-20 | 25,867 (10.0%) | 29,525 (14.1%) | 111,629 (1.7%)
| May-20 | 7475 (2.9%) | 10,170 (4.9%) | 66,563 (1.0%)
| Jun-20 | 2698 (1.0%) | 3740 (1.8%) | 25,007 (0.4%)
| Jul-20 | 1077 (0.4%) | 1232 (0.6%) | 18,905 (0.3%)
| Aug-20 | 911 (0.4%) | 514 (0.2%) | 29,130 (0.4%)
| Sep-20 | 3945 (1.5%) | 2092 (1.0%) | 124,294 (1.9%)
| Oct-20 | 15,235 (5.9%) | 14,004 (6.7%) | 474,083 (7.2%)
| Nov-20 | 23,218 (8.9%) | 22,905 (11.0%) | 518,220 (7.8%)
| Dec-20 | 31,468 (12.1%) | 31,564 (15.1%) | 852,653 (12.9%)
| Jan-21 | 60,389 (23.3%) | 40,122 (19.2%) | 1,068,457 (16.1%)
| Feb-21 | 19,503 (7.5%) | 12,959 (6.2%) | 289,488 (4.4%)
| Mar-21 | 5809 (2.2%) | 3750 (1.8%) | 134,516 (2.0%)
| Apr-21 | 1929 (0.7%) | 1110 (0.5%) | 58,209 (0.9%)
| May-21 | 1370 (0.5%) | 477 (0.2%) | 61,016 (0.9%)
| Jun-21 | 3756 (1.4%) | 1325 (0.6%) | 293,512 (4.4%)
| Jul-21 | 13,984 (5.4%) | 4377 (2.1%) | 926,889 (14.0%)
| Aug-21 | 15,578 (6.0%) | 6394 (3.1%) | 775,051 (11.7%)
| Sep-21 | 13,107 (5.0%) | 5027 (2.4%) | 757,011 (11.4%)
Hospital outcome |  |  |
| Death | 51,948 (20.0%) | 69,243 (33.2%) | N/A
| Discharge | 191,663 (73.8%) | 107,815 (51.6%) | N/A
| Right-censored in hospital | 16,116 (6.2%) | 31,793 (15.2%) | N/A
Median length of stay following admission/positive test (days)
| Death | 8 days | 11 days | N/A
| Discharge | 5 days | 13 days | N/A
Vaccination status at date of admission (for admissions occurring January and
July 2021)
| Unvaccinated | 97,441 (72.0%) | N/A | N/A
| <21 days after first dose | 10,774 (8.0%) | N/A | N/A
|  $\geq$21 days after first dose | 7885 (5.8%) | N/A | N/A
|  $\geq$14 days after second dose | 19,325 (14.3%) | N/A | N/A
Charlson comorbidity index |  |
| 0 | 92,753 (38.8%) | N/A | N/A
| 1-2 | 93,436 (39.1%) | N/A | N/A
| 3-4 | 35,527 (14.9%) | N/A | N/A
| 5+ | 17,190 (7.2%) | N/A | N/A
Hospital load at time of admission (as proportion of busiest week)
| 0-20% | 61,406 (23.6%) | N/A | N/A
| 20-40% | 64,722 (24.9%) | N/A | N/A
| 40-60% | 49,529 (19.1%) | N/A | N/A
| 60-80% | 40,385 (15.5%) | N/A | N/A
| 80-90% | 20,228 (7.8%) | N/A | N/A
| 90-100% | 23,457 (9.0%) | N/A | N/A
Route of admission |  |  |
| Via emergency ward | 204,151 (78.6%) | N/A | N/A
| Directly to hospital | 55,576 (21.4%) | N/A | N/A
Table 2: * Table 2: Hospitalised fatality risk by vaccine status at hospital admission and age group. Figures in brackets represent 95% confidence intervals. Estimates are replaced with a dash (-) where insufficient information was available. |  |  |  |
---|---|---|---|---
| Age
---
group
Unvaccinated |  | <21 days after
---
first dose
|  $\geq$21 days after
---
first dose
|  $\geq$14 days after
---
second dose
[0,15) | 0.2% (0.1 - 0.4%) | - | - | -
[15,25) | 0.3% (0.2 - 0.5%) | 1.3% (0.3 - 5.3%) | - | -
[25,45) | 1.7% (1.5 - 1.9%) | 2.1% (1.3 - 3.5%) | 1.2% (0.7 - 2.2%) | -
[45,65) | 10.1% (9.8 - 10.5%) | 8.7% (7.5 - 10.1%) | 6.1% (4.9 - 7.7%) | 7.5% (6.2 - 9.0%)
[65,75) | 25.3% (24.5 - 26.0%) | 22.5% (20.5 - 24.7%) | 18.2% (15.6 - 21.1%) | 14.9% (12.9 - 17.2%)
[75,85) | 38.6% (37.7 - 39.6%) | 34.5% (32.8 - 36.2%) | 26.2% (24.1 - 28.5%) | 22.5% (20.4 - 24.8%)
[85,Inf] | 49.9% (48.7 - 51.1%) | 47.0% (45.2 - 48.9%) | 37.7% (35.4 - 40.2%) | 32.0% (29.1 - 35.2%)

## Figures

Figure 1: Observed number of individuals hospitalised with COVID-19, by week
of admission. March 2020 to September 2021. Annotations shown for wave 1, wave
2, and wave 3. $n=259,727$ individuals. Figure 2: Vaccination status of
hospitalised individuals, by month of admission and age group. December 2020
to September 2021. $n=166,893$ individuals with vaccination status reported.
Figure 3: Hospitalised fatality risk (panel a) and median length of stay
(panel b) by month of admission. March 2020 to September 2021. Unadjusted for
other covariates. $n=259,727$ individuals. Error bars are 95% confidence
intervals. Figure 4: Hospitalised fatality risk (panel a) and median length of
stay (panel b) by month of admission and age group. March 2020 to September
2021. Unadjusted for other covariates. $n=259,727$ individuals with age
reported. Error bars are 95% confidence intervals. Figure 5: Hospitalised
fatality sub-distribution hazard ratio by month of hospital admission. March
2020 to September 2021. Model includes stratification on age group, region of
residence, and vaccination status, and regression adjustment (main effects) on
month of hospital admission, sex, ethnicity, IMD quintile, hospital load, and
CCI. Reference group: June 2020. $n=238,897$ individuals with necessary
information reported. Figure shows point estimate of hazard ratio with 95%
confidence intervals. Figure 6: Hospitalised fatality sub-distribution hazard
ratio by vaccine status. January 2021 to September 2021. Model includes
stratification on age group, region of residence, and month of hospital
admission, and regression adjustment (main effects) on vaccine status, sex,
ethnicity, IMD quintile, hospital load, and CCI. Reference group:
Unvaccinated. $n=126,679$ individuals with necessary information reported.
Figure shows point estimate of hazard ratio with 95% confidence intervals.

## Supplementary information

## Aalen-Johansen estimator

If the competing risks of events are not independent, and the magnitude of the
competing risk is large, the assumptions of conventional survival analysis
methods such as Kaplan-Meier and Cox proportional hazards regression may
provide biased estimates of risk, or of covariate effects on the rate of
events, respectively [1]. In the case of mortality within 90 days of
hospitalisation with COVID-19, the competing risk of discharge may well be
large, e.g. for individuals discharged to palliative care.

The Aalen-Johansen estimator is the standard non-parametric estimate of the
cumulative incidence function for competing risk [2], also described as the
matrix version of the Kaplan-Meier estimator.

Let the transition hazard from state $i\in S$ to state $j\in S$, $i\neq j$ be
defined as:

$\alpha_{i,j}(t)dt=P(X_{t+dt}=j\ |\ X_{t}=i)$

and let $\mathbf{A}(t)$ be the matrix of cumulative transition hazards:

$\displaystyle A_{i,j}(t)=\int_{0}^{t}{\alpha_{i,j}(u)du}$ $\displaystyle
A_{i,i}(t)\ =\ -\sum_{j\neq i}{A_{i,j}(t)}$

then, defining as $P_{i,j}(s,t)=P(X_{t}=j\ |\ X_{s}=i),$ for $i,j\in S$,
$s\leq t$ the probability that an individual in state $s$ at time $i$ will be
in state $t$ at time $j$, the Aalen-Johansen estimator is given by the matrix
of transition probabilities:

$\mathbf{P}(s,t)=\prod_{s,t}{(\mathbf{I}+d\mathbf{A}(u))}$

The cumulative incidence function is a special case of the Aalen-Johansen
estimate where:

$C_{k}(t)=\ \int_{0}^{t}{\alpha_{k}(u)S(u)du}$

$\alpha_{k}$ is the incidence function for outcome $k$, and $S(u)$ is the
overall survival curve.

## Fine-Gray proportional hazards regression

The Fine-Gray model estimates the hazard of a competing event (so-termed the
sub-distribution hazard) among the risk set of those yet to experience an
event of the type of interest by time $t$ [3]. The risk set therefore consists
of both those who have yet to experience any event and those who have yet to
experience the event of interest (e.g. death) but have experienced a competing
event (e.g. discharge).

The subdistribution hazard is defined as the instantaneous risk of dying (from
a cause $k$) given that the individual has not already died:

$h_{k}(t)=\lim_{\delta\rightarrow 0}{\left\\{\frac{P(t\leq T<t+\delta t,K=k\
|\ T>t\text{ or }(T\leq t\text{ \& }K\neq k))}{\delta t}\right\\}}$

Fine-Gray regression links the subdistribution hazard to the Aalen-Johansen
cumulative incidence estimator through the relationship:

$h_{k}(t)=-\frac{d\log{(1-C_{k}(t))}}{dt}$

Covariate effects on the sub-distribution hazard can then be interpreted as
covariate effects on the cumulative incidence, or marginal probability, of a
competing event (in this case hospitalised fatality).

## Stratification

Stratified survival analyses enable appropriate adjustment for important
confounders, by allowing the baseline hazard to vary across strata [4].
Stratification is a similar principle to matched designs, except rather than a
$1:n$ ratio of cases to controls, as many ($a:b$ for $a$ and $b$ both $\geq
1$) cases and controls as possible within each strata are used.

For the regression on month of admission, stratification was by age group,
region of residence and vaccination status, with regression adjustment (main
effects) on sex, ethnicity, index of multiple deprivation (IMD) quintile and
Charlson comorbidity index (CCI). For the regression on vaccination status,
stratification was by age group, region of residence and month of hospital
admission, with regression adjustment (main effects) similarly on sex,
ethnicity, IMD quintile and CCI.

## Consistency in model estimates

Supplementary figure 7 demonstrates the high degree of agreement between the
Aalen-Johansen and Fine-Gray model estimates.

## Epidemic phase bias

A form of bias, often ignored in epidemic studies, is the relationship between
the time from infection to symptom onset, and an individual’s eventual
outcome: e.g. those who go on to die may experience more rapid onset of
symptoms following infection. Since estimates must be conditioned on an
observed quantity (e.g. symptom onset date or hospital admission date) rather
than the unobserved infection date, this relationship can introduce bias into
results when an epidemic is in a mode of growth or decline [5]. The resulting
bias has been termed “epidemic phase bias” and may result in hazards being
over or under-estimated.

To correct for this bias, a time shift of $c$ days should be added to records
with the outcome of interest (e.g. mortality), where $c$ is the mean
difference in time from infection to symptom onset date between those
experiencing the outcome and those not, as proposed by Seaman et al. [5]. As
the value of $c$ is typically unknown, sensitivity analysis with differing
values of $c$ can be used to assess the susceptibility of results to this
bias.

For the sensitivity analysis in this study we shifted the date of symptom
onset backwards in time by $c=0,1,2,3,4$ days for those who died, to mitigate
against the effect of more rapid symptom onset for those with more severe
illness, where the shift $c$ represents the average difference in time from
infection to symptom onset between those patients who died and those who did
not. The effect of this shift is shown in Supplementary Figure 8.

## Supplementary figures

Supplementary figure 1: Hospitalised fatality risk (panel a) and median length
of stay (panel b) by month of admission and sex. March 2020 to September 2021.
Unadjusted for other covariates. $n=259,727$ individuals with sex reported.
Error bars are 95% confidence intervals. Supplementary figure 2: Hospitalised
fatality risk (panel a) and median length of stay (panel b) by month of
admission and ethnicity. March 2020 to September 2021. Unadjusted for other
covariates. $n=259,727$ individuals with ethnicity reported. Error bars are
95% confidence intervals. Supplementary figure 3: Hospitalised fatality risk
(panel a) and median length of stay (panel b) by month of admission and region
of residence. March 2020 to September 2021. Unadjusted for other covariates.
$n=259,727$ individuals with region of residence reported. Error bars are 95%
confidence intervals. Supplementary figure 4: Hospitalised fatality risk
(panel a) and median length of stay (panel b) by month of admission and CCI.
March 2020 to September 2021. Unadjusted for other covariates. $n=238,906$
individuals with comorbidity information reported. Error bars are 95%
confidence intervals. Supplementary figure 5: Hospitalised fatality risk
(panel a) and median length of stay (panel b) by month of admission and
measure of hospital load. March 2020 to September 2021. Unadjusted for other
covariates. $n=259,727$ individuals with hospital admission date reported.
Error bars are 95% confidence intervals. Supplementary figure 6: Hospitalised
fatality sub-distribution hazard ratios for sex, ethnicity, IMD quintile,
hospital load and CCI. March 2020 to September 2021. Model includes
stratification on age group, region of residence, and vaccination status, and
regression adjustment (main effects) on month of hospital admission, sex,
ethnicity, IMD quintile, hospital load, and CCI. $n=238,897$ individuals with
necessary information reported. Figure shows point estimate of hazard ratio
with 95% confidence intervals. Supplementary figure 7: Aalen-Johansen and
Fine-Gray cumulative fatality estimates for first 60 days following hospital
admission for selected months. March 2020 to September 2021. $n=259,727$
individuals. Error bands are 95% confidence intervals. Figure shows high
degree of agreement between the two models. Supplementary figure 8:
Hospitalised fatality sub-distribution hazard ratio by month of symptom onset
and sensitivity. March 2020 to September 2021. Model includes stratification
on age group, region of residence, and vaccination status, and regression
adjustment (main effects) on month of hospital admission, sex, ethnicity, IMD
quintile, hospital load, and CCI. Figure shows results of sensitivity analyses
where the date of symptom onset was shifted backwards in time by $c=0,1,2,3,4$
days for those who died, but not for those who were discharged. Reference
group: June 2020. $n=259,727$ individuals with sex reported. Figure shows
point estimate of hazard ratio with 95% confidence intervals.

## Supplementary tables

Table 3: * Supplementary table 1: Hospital outcomes according to person characteristic. Figures in brackets represent 95% confidence intervals. |  |  |  |
---|---|---|---|---
Characteristic | Death | Discharge |  | Right-censored
---
in hospital
Age |  |  |
| 0-14 | 13 (0.2%) | 6272 (94.3%) | 365 (5.5%)
| 15-24 | 42 (0.5%) | 8509 (94.8%) | 421 (4.7%)
| 35-44 | 735 (1.7%) | 40,722 (92.4%) | 2637 (6.0%)
| 45-64 | 7310 (9.8%) | 61,162 (82.4%) | 5786 (7.8%)
| 65-74 | 10,222 (24.2%) | 29,369 (69.4%) | 2716 (6.4%)
| 75-84 | 17,060 (35.7%) | 28,133 (58.9%) | 2590 (5.4%)
| 85+ | 16,566 (46.5%) | 17,496 (49.1%) | 1601 (4.5%)
Sex |  |  |
| Male | 30,744 (22.7%) | 96,043 (70.9%) | 8632 (6.4%)
| Female | 21,204 (17.1%) | 95,620 (76.9%) | 7484 (6.0%)
Ethnicity |  |  |
| White | 42,799 (21.9%) | 141,406 (72.3%) | 11,291 (5.8%)
| Asian | 5011 (15.6%) | 24,910 (77.4%) | 2270 (7.1%)
| Black | 2220 (14.4%) | 11,738 (76.3%) | 1436 (9.3%)
| Mixed/Other/Unknown | 1918 (11.5%) | 13,609 (81.8%) | 1119 (6.7%)
Region of residence |  |  |
| London | 8519 (18.2%) | 34,288 (73.2%) | 4047 (8.6%)
| East Midlands | 4633 (20.5%) | 16,711 (74.0%) | 1227 (5.4%)
| East of England | 6194 (23.5%) | 18,971 (72.1%) | 1158 (4.4%)
| North East | 2858 (18.9%) | 11,688 (77.2%) | 585 (3.9%)
| North West | 9016 (21.0%) | 31,020 (72.1%) | 2981 (6.9%)
| South East | 6568 (20.1%) | 23,967 (73.2%) | 2205 (6.7%)
| South West | 2874 (16.5%) | 14,030 (80.7%) | 487 (2.8%)
| West Midlands | 6177 (20.7%) | 21,996 (73.8%) | 1635 (5.5%)
| Yorkshire and Humber | 5109 (19.7%) | 18,992 (73.4%) | 1791 (6.9%)
Index of multiple deprivation |  |  |
| 1st quintile (most deprived) | 13,715 (18.8%) | 54,719 (74.9%) | 4666 (6.4%)
| 2nd quintile | 11,808 (19.8%) | 44,100 (73.8%) | 3846 (6.4%)
| 3rd quintile | 9834 (20.3%) | 35,572 (73.4%) | 3052 (6.3%)
| 4th quintile | 9066 (21.3%) | 31,031 (72.8%) | 2511 (5.9%)
| 5th quintile (least deprived) | 7525 (21.0%) | 26,241 (73.3%) | 2041 (5.7%)
Month of hospital admission |  |  |
| Mar-20 | 4386 (35.3%) | 6494 (52.3%) | 1528 (12.3%)
| Apr-20 | 8767 (33.9%) | 14,704 (56.8%) | 2396 (9.3%)
| May-20 | 1976 (26.4%) | 4706 (63.0%) | 793 (10.6%)
| Jun-20 | 497 (18.4%) | 1970 (73.0%) | 231 (8.6%)
| Jul-20 | 130 (12.1%) | 868 (80.6%) | 79 (7.3%)
| Aug-20 | 104 (11.4%) | 745 (81.8%) | 62 (6.8%)
| Sep-20 | 587 (14.9%) | 3212 (81.4%) | 146 (3.7%)
| Oct-20 | 2774 (18.2%) | 11,770 (77.3%) | 691 (4.5%)
| Nov-20 | 4591 (19.8%) | 17,597 (75.8%) | 1030 (4.4%)
| Dec-20 | 6687 (21.3%) | 23,060 (73.3%) | 1721 (5.5%)
| Jan-21 | 13,035 (21.6%) | 44,028 (72.9%) | 3326 (5.5%)
| Feb-21 | 3311 (17.0%) | 15,294 (78.4%) | 898 (4.6%)
| Mar-21 | 582 (10.0%) | 4965 (85.5%) | 262 (4.5%)
| Apr-21 | 160 (8.3%) | 1683 (87.2%) | 86 (4.5%)
| May-21 | 112 (8.2%) | 1194 (87.2%) | 64 (4.7%)
| Jun-21 | 284 (7.6%) | 3271 (87.1%) | 201 (5.4%)
| Jul-21 | 1149 (8.2%) | 12,116 (86.6%) | 719 (5.1%)
| Aug-21 | 1556 (10.0%) | 13,127 (84.3%) | 895 (5.7%)
| Sep-21 | 1260 (9.6%) | 10,859 (82.8%) | 988 (7.5%)
| Vaccination status at date of admission
---
(for admissions occurring January to September 2021)
| Unvaccinated | 14,360 (14.7%) | 77,720 (79.8%) | 5361 (5.5%)
| <21 days after first dose | 2895 (26.9%) | 7369 (68.4%) | 510 (4.7%)
|  $\geq$21 days after first dose | 1346 (17.1%) | 6181 (78.4%) | 358 (4.5%)
|  $\geq$14 days after second dose | 2844 (14.7%) | 15,262 (79.0%) | 1208 (6.3%)
Charleson comorbidity index |  |  |
| 0 | 5837 (6.3%) | 86,731 (93.5%) | 185 (0.2%)
| 1-2 | 20,045 (21.5%) | 73,062 (78.2%) | 329 (0.4%)
| 3-4 | 13,216 (37.2%) | 22,125 (62.3%) | 186 (0.5%)
| 5+ | 7384 (43.0%) | 9745 (56.7%) | 61 (0.4%)
Hospital load at time of admission (as proportion of busiest week)
| 0-20% | 8815 (14.4%) | 48,676 (79.3%) | 3915 (6.4%)
| 20-40% | 12,784 (19.8%) | 47,937 (74.1%) | 4001 (6.2%)
| 40-60% | 11,041 (22.3%) | 35,598 (71.9%) | 2890 (5.8%)
| 60-80% | 9345 (23.1%) | 28,562 (70.7%) | 2478 (6.1%)
| 80-90% | 4641 (22.9%) | 14,302 (70.7%) | 1285 (6.4%)
| 90-100% | 5322 (22.7%) | 16,588 (70.7%) | 1547 (6.6%)
Route of admission* |  |  |
| Via emergency ward | 44,907 (22.0%) | 143,287 (70.2%) | 15,957 (7.8%)
| Direct to hospital | 7041 (12.7%) | 48,376 (87.0%) | 159 (0.3%)

*Assessed through existence of matched record in ECDS dataset.

Table 4: * Supplementary table 2: Hospitalised fatality risk and median length of stay (days) in hospital by month of hospital admission (unadjusted for other covariates). Figures in brackets represent 95% confidence intervals. |  |  |
---|---|---|---
| Month of
---
hospital admission
Hospitalised fatality risk |  | Median LOS
---
prior to death
| Median LOS
---
prior to discharge
Mar-20 | 40.3% (39.4 - 41.3%) | 5.6 (5.5 - 5.6) | 5.9 (5.8 - 6.0)
Apr-20 | 37.4% (36.7 - 38.0%) | 5.2 (5.2 - 5.3) | 5.8 (5.8 - 5.9)
May-20 | 29.7% (28.6 - 30.8%) | 6.5 (6.4 - 6.7) | 5.6 (5.5 - 5.7)
Jun-20 | 20.3% (18.8 - 21.9%) | 7.7 (7.5 - 8.0) | 4.9 (4.8 - 5.1)
Jul-20 | 13.1% (11.1 - 15.3%) | 10.4 (9.7 - 11.0) | 4.0 (3.8 - 4.2)
Aug-20 | 12.3% (10.3 - 14.8%) | 9.9 (9.2 - 10.9) | 3.1 (2.9 - 3.3)
Sep-20 | 15.5% (14.4 - 16.7%) | 9.0 (8.7 - 9.3) | 4.1 (4.0 - 4.2)
Oct-20 | 19.1% (18.5 - 19.7%) | 8.5 (8.4 - 8.7) | 4.5 (4.5 - 4.6)
Nov-20 | 20.7% (20.2, 21.3%) | 8.4 (8.3 - 8.5) | 4.8 (4.8 - 4.9)
Dec-20 | 22.5% (22.1 - 23.0%) | 8.5 (8.4 - 8.6) | 5.0 (5.0 - 5.1)
Jan-21 | 22.8% (22.5 - 23.2%) | 7.5 (7.5 - 7.6) | 4.9 (4.9 - 4.9)
Feb-21 | 17.8% (17.3 - 18.4%) | 7.8 (7.6 - 7.9) | 4.6 (4.5 - 4.6)
Mar-21 | 10.5% (9.7 - 11.4%) | 8.7 (8.4 - 9.0) | 3.6 (3.6 - 3.7)
Apr-21 | 8.7% (7.5 - 10.1%) | 8.6 (8.3 - 9.1) | 3.2 (3.1 - 3.3)
May-21 | 8.6% (7.2 - 10.3%) | 10.0 (9.5 - 10.7) | 2.8 (2.7 - 2.9)
Jun-21 | 8.1% (7.2 - 9.0%) | 10.4 (10.1 - 10.8) | 2.7 (2.6 - 2.8)
Jul-21 | 8.7% (8.3 - 9.2%) | 9.9 (9.7 - 10.2) | 3.0 (3.0 - 3.1)
Aug-21 | 10.7% (10.2 - 11.2%) | 9.6 (9.4 - 9.8) | 3.2 (3.2 - 3.3)
Sep-21 | 10.5% (10.0 - 11.1%) | 7.6 (7.5 - 7.8) | 3.6 (3.5 - 3.6)

Table 5: * Supplementary table 3: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and age group (unadjusted for other covariates). Estimates are replaced with a dash (-) where insufficient information was available. Figures in brackets represent 95% confidence intervals. |  |  |  |  |
---|---|---|---|---|---
| Month of hospital
---
admission
0-14 | 15-24 | 25-44 | 45-64
Mar-20 |  |  |  |
| HFR | 1.4% (0.4 - 5.7%) | 4.0% (1.7 - 9.4%) | 5.7% (4.5 - 7.3%) | 22.3% (20.9 - 23.9%)
| Median LOS (death) | 6.0 (2.9 - 7.8) | 4.0 (1.4 - 5.9) | 7.7 (7.1 - 8.3) | 7.5 (7.3 - 7.9)
| Median LOS (discharge) | 1.0 (0.9 - 1.1) | 2.4 (2.0 - 2.8) | 3.0 (2.8 - 3.2) | 5.6 (5.4 - 5.7)
Apr-20 |  |  |  |
| HFR | 0.5% (0.1 - 3.9%) | 2.6% (1.1 - 6.2%) | 5.0% (4.1 - 6.1%) | 18.2% (17.3 - 19.2%)
| Median LOS (death) | 5.0 (5.0 - 5.0) | 4.7 (0.8 - 8.9) | 5.3 (5.1 - 5.6) | 6.7 (6.5 - 6.8)
| Median LOS (discharge) | 1.4 (1.1 - 1.7) | 1.6 (1.3 - 1.9) | 2.9 (2.8 - 3.1) | 4.8 (4.7 - 4.8)
May-20 |  |  |  |
| HFR | 1.0% (0.1 - 6.7%) | 0.7% (0.1 - 5.3%) | 1.9% (1.1 - 3.2%) | 13.3% (11.6 - 15.3%)
| Median LOS (death) | 6.0 (6.0 - 6.0) | 3.0 (3.0 - 3.0) | 8.5 (8.3 - 10.2) | 7.8 (7.4 - 8.4)
| Median LOS (discharge) | 1.1 (0.9 - 1.4) | 1.0 (0.9 - 1.3) | 1.8 (1.6 - 1.9) | 4.3 (4.2 - 4.5)
Jun-20 |  |  |  |
| HFR | 1.7% (0.2 - 11.6%) | 1.4% (0.2 - 9.6%) | 1.2% (0.5 - 3.3%) | 7.9% (5.9 - 10.5%)
| Median LOS (death) | 2.0 (2.0 - 2.0) | 16.0 (16.0 - 16.0) | 0.8 (0.6 - 1.6) | 8.4 (8.0 - 9.3)
| Median LOS (discharge) | 0.9 (0.8 - 1.2) | 1.6 (1.1 - 2.0) | 1.4 (1.2 - 1.6) | 3.9 (3.5 - 4.2)
Jul-20 |  |  |  |
| HFR | - | - | - | 8.8% (5.9 - 13.0%)
| Median LOS (death) | - | - | - | 14.0 (11.9 - 16.3)
| Median LOS (discharge) | - | - | - | 4.7 (4.3 - 5.0)
Aug-20 |  |  |  |
| HFR | - | - | 1.0% (0.3 - 4.0%) | 7.9% (5.1 - 12.3%)
| Median LOS (death) | - | - | 12.0 (8.1 - 14.2) | 12.0 (10.1 - 13.9)
| Median LOS (discharge) | - | - | 1.4 (1.1 - 1.7) | 3.9 (3.4 - 4.3)
Sep-20 |  |  |  |
| HFR | - | 0.5% (0.1 - 3.8%) | 0.7% (0.3 - 1.6%) | 4.8% (3.7 - 6.3%)
| Median LOS (death) | - | 18.0 (18.0 - 18.0) | 11.0 (7.6 - 14.1) | 13.6 (12.5 - 14.4)
| Median LOS (discharge) | - | 1.0 (0.9 - 1.1) | 2.1 (1.9 - 2.2) | 4.7 (4.5 - 4.9)
Oct-20 |  |  |  |
| HFR | - | 0.2% (0.0 - 1.3%) | 1.2% (0.8 - 1.8%) | 8.1% (7.3 - 9.0%)
| Median LOS (death) | - | 10.0 (10.0 - 10.0) | 7.5 (5.6 - 8.3) | 12.6 (12.2 - 13.0)
| Median LOS (discharge) | - | 0.9 (0.9 - 1.0) | 2.0 (1.9 - 2.2) | 4.3 (4.2 - 4.4)
Nov-20 |  |  |  |
| HFR | 0.2% (0.0 - 1.6%) | 0.5% (0.2 - 1.5%) | 1.4% (1.1 - 1.9%) | 8.6% (8.0 - 9.4%)
| Median LOS (death) | 0.5 (0.5 - 0.5) | 5.0 (3.5 - 5.8) | 10.0 (9.4 - 11.0) | 12.7 (12.3 - 13.1)
| Median LOS (discharge) | 0.9 (0.9 - 0.9) | 1.0 (0.9 - 1.1) | 2.1 (2.0 - 2.2) | 4.5 (4.4 - 4.5)
Dec-20 |  |  |  |
| HFR | - | 0.3% (0.1 - 1.1%) | 2.0% (1.6 - 2.4%) | 10.1% (9.5 - 10.7%)
| Median LOS (death) | - | 9.5 (7.6 - 10.6) | 13.6 (13.0 - 14.4) | 12.4 (12.1 - 12.7)
| Median LOS (discharge) | - | 1.2 (1.0 - 1.3) | 2.4 (2.3 - 2.5) | 4.8 (4.7 - 4.8)
Jan-21 |  |  |  |
| HFR | 0.2% (0.1 - 1.0%) | 0.7% (0.4 - 1.3%) | 2.2% (1.9 - 2.5%) | 10.8% (10.3 - 11.3%)
| Median LOS (death) | 16.0 (16.0 - 16.0) | 8.0 (3.8 - 9.8) | 12.4 (11.8 - 13.0) | 11.6 (11.4 - 11.8)
| Median LOS (discharge) | 0.9 (0.9 - 1.0) | 1.3 (1.2 - 1.4) | 2.8 (2.7 - 2.8) | 4.6 (4.6 - 4.7)
Feb-21 |  |  |  |
| HFR | - | - | 1.7% (1.3 - 2.2%) | 9.5% (8.8 - 10.3%)
| Median LOS (death) | - | - | 7.0 (6.5 - 9.8) | 11.6 (11.2 - 11.9)
| Median LOS (discharge) | - | - | 2.3 (2.3 - 2.4) | 4.4 (4.3 - 4.5)
Mar-21 |  |  |  |
| HFR | - | - | 1.2% (0.7 - 1.9%) | 5.8% (4.8 - 6.9%)
| Median LOS (death) | - | - | 7.0 (3.5 - 12.8) | 13.6 (12.9 - 15.2)
| Median LOS (discharge) | - | - | 2.0 (1.9 - 2.2) | 4.0 (3.8 - 4.1)
Apr-21 |  |  |  |
| HFR | - | - | 0.3% (0.1 - 1.4%) | 4.6% (3.1 - 6.8%)
| Median LOS (death) | - | - | 19.5 (9.8 - 25.0) | 13.0 (12.5 - 14.3)
| Median LOS (discharge) | - | - | 2.0 (1.8 - 2.3) | 3.6 (3.4 - 3.8)
May-21 |  |  |  |
| HFR | - | - | 1.0% (0.4 - 2.4%) | 9.6% (6.8 - 13.5%)
| Median LOS (death) | - | - | 14.0 (7.9 - 20.8) | 18.0 (15.0 - 18.8)
| Median LOS (discharge) | - | - | 2.4 (2.2 - 2.7) | 4.0 (3.7 - 4.3)
Jun-21 |  |  |  |
| HFR | 0.9% (0.2 - 3.5%) | - | 1.2% (0.8 - 2.0%) | 9.7% (7.9 - 12.0%)
| Median LOS (death) | 7.5 (4.8 - 9.0) | - | 19.0 (17.5 - 20.5) | 13.6 (11.6 - 15.2)
| Median LOS (discharge) | 0.9 (0.8 - 0.9) | - | 2.2 (2.1 - 2.4) | 4.0 (3.8 - 4.2)
Jul-21 |  |  |  |
| HFR | - | 0.3% (0.1 - 0.8%) | 1.5% (1.2 - 1.9%) | 8.0% (7.1 - 9.0%)
| Median LOS (death) | - | 22.5 (17.8 - 25.9) | 15.5 (13.9 - 16.7) | 13.1 (12.7 - 13.6)
| Median LOS (discharge) | - | 1.2 (1.1 - 1.3) | 2.2 (2.1 - 2.3) | 4.7 (4.6 - 4.8)
Aug-21 |  |  |  |
| HFR | 0.2% (0.1 - 0.9%) | 0.6% (0.3 - 1.3%) | 1.1% (0.8 - 1.5%) | 8.4% (7.6 - 9.4%)
| Median LOS (death) | 16.0 (8.2 - 20.4) | 16.0 (7.9 - 17.6) | 13.4 (12.7 - 14.0) | 12.4 (11.9 - 13.2)
| Median LOS (discharge) | 0.9 (0.9 - 1.0) | 1.2 (1.1 - 1.3) | 2.0 (2.0 - 2.1) | 4.2 (4.1 - 4.3)
Sep-21 |  |  |  |
| HFR | 0.1% (0.0 - 1.0%) | 0.3% (0.1 - 1.2%) | 0.8% (0.5 - 1.2%) | 6.7% (5.9 - 7.7%)
| Median LOS (death) | 9.0 (9.0 - 9.0) | 19.5 (16.8 - 21.0) | 11.0 (10.0 - 14.0) | 10.4 (10 - 10.9)
| Median LOS (discharge) | 0.8 (0.8 - 0.9) | 1.0 (1.0 - 1.1) | 2.1 (2.0 - 2.2) | 4.2 (4.0 - 4.3)
Table 6: * Supplementary table 3 continued |  |  |  |
---|---|---|---|---
| Month of hospital
---
admission
65-74 | 75-84 | 85+
Mar-20 |  |  |
| HFR | 43.2% (41.1 - 45.4%) | 57.3% (55.5 - 59.2%) | 66.5% (64.4 - 68.7%)
| Median LOS (death) | 6.2 (6.0 - 6.4) | 4.9 (4.8 - 5.0) | 5.0 (4.8 - 5.1)
| Median LOS (discharge) | 6.8 (6.6 - 7.0) | 7.8 (7.6 - 8.0) | 9.5 (9.3 - 9.8)
Apr-20 |  |  |
| HFR | 38.2% (36.8 - 39.7%) | 50.4% (49.2 - 51.7%) | 60.0% (58.7 - 61.4%)
| Median LOS (death) | 5.6 (5.5 - 5.8) | 4.8 (4.7 - 4.9) | 4.9 (4.8 - 5.0)
| Median LOS (discharge) | 6.6 (6.5 - 6.7) | 7.8 (7.7 - 7.9) | 8.5 (8.4 - 8.7)
May-20 |  |  |
| HFR | 27.0% (24.4 - 29.8%) | 41.1% (38.8 - 43.5%) | 48.5% (46.2 - 50.9%)
| Median LOS (death) | 6.9 (6.6 - 7.3) | 5.9 (5.7 - 6.1) | 6.8 (6.5 - 7.0)
| Median LOS (discharge) | 6.6 (6.3 - 6.9) | 8.2 (7.9 - 8.4) | 8.6 (8.3 - 8.8)
Jun-20 |  |  |
| HFR | 20.6% (17.0 - 25.0%) | 36.0% (32.3 - 40.2%) | 33.6% (29.6 - 38.1%)
| Median LOS (death) | 9.4 (8.9 - 10.2) | 7.5 (7.1 - 7.9) | 7.1 (6.6 - 7.7)
| Median LOS (discharge) | 5.9 (5.5 - 6.3) | 7.4 (7.1 - 7.7) | 8.9 (8.5 - 9.3)
Jul-20 |  |  |
| HFR | 15.2% (10.5 - 22.2%) | 24.6% (19.2 - 31.5%) | 27.4% (20.8 - 36.1%)
| Median LOS (death) | 11.8 (10.4 - 12.6) | 7.8 (7.3 - 9.2) | 6.3 (5.9 - 7.7)
| Median LOS (discharge) | 4.3 (3.8 - 4.8) | 6.7 (6.1 - 7.3) | 8.6 (7.8 - 9.5)
Aug-20 |  |  |
| HFR | 19.5% (13.5 - 28.1%) | 25.8% (19.3 - 34.7%) | 34.2% (25.4 - 46.2%)
| Median LOS (death) | 11.7 (9.5 - 15.7) | 12.0 (9.7 - 12.5) | 8.1 (7.9 - 8.5)
| Median LOS (discharge) | 4.4 (3.9 - 5.3) | 7.0 (6.3 - 8.3) | 7.4 (6.7 - 8.4)
Sep-20 |  |  |
| HFR | 23.3% (20.2 - 26.7%) | 30.3% (27.0 - 33.9%) | 44.7% (40.0 - 50.0%)
| Median LOS (death) | 12.4 (11.9 - 13.2) | 7.9 (7.4 - 8.5) | 6.8 (6.3 - 7.5)
| Median LOS (discharge) | 5.8 (5.5 - 6.1) | 6.6 (6.3 - 6.9) | 8.1 (7.5 - 8.8)
Oct-20 |  |  |
| HFR | 21.3% (19.8 - 22.9%) | 34.0% (32.4 - 35.7%) | 44.7% (42.5 - 47.1%)
| Median LOS (death) | 10.0 (9.7 - 10.3) | 8.0 (7.7 - 8.2) | 7.4 (7.1 - 7.6)
| Median LOS (discharge) | 5.5 (5.4 - 5.6) | 6.8 (6.7 - 7.0) | 10.4 (10.1 - 10.7)
Nov-20 |  |  |
| HFR | 23.6% (22.3 - 24.9%) | 33.2% (31.9 - 34.6%) | 46.0% (44.3 - 47.7%)
| Median LOS (death) | 9.3 (9.0 - 9.7) | 7.6 (7.5 - 7.8) | 7.6 (7.5 - 7.8)
| Median LOS (discharge) | 5.8 (5.7 - 5.9) | 7.7 (7.6 - 7.8) | 9.3 (9.1 - 9.6)
Dec-20 |  |  |
| HFR | 26.3% (25.1 - 27.6%) | 38.5% (37.3 - 39.8%) | 49.4% (48.0 - 50.9%)
| Median LOS (death) | 9.7 (9.4 - 9.9) | 7.6 (7.4 - 7.7) | 7.6 (7.4 - 7.7)
| Median LOS (discharge) | 6.4 (6.3 - 6.5) | 7.9 (7.8 - 8.0) | 10.1 (10.0 - 10.3)
Jan-21 |  |  |
| HFR | 26.1% (25.3 - 27.0%) | 38.6% (37.7 - 39.5%) | 49.5% (48.4 - 50.6%)
| Median LOS (death) | 8.9 (8.7 - 9.1) | 6.6 (6.5 - 6.7) | 6.6 (6.5 - 6.7)
| Median LOS (discharge) | 5.9 (5.8 - 6.0) | 7.4 (7.4 - 7.5) | 8.6 (8.4 - 8.7)
Feb-21 |  |  |
| HFR | 21.9% (20.5 - 23.3%) | 31.8% (30.2 - 33.5%) | 42.9% (40.9 - 44.9%)
| Median LOS (death) | 8.4 (8.1 - 8.7) | 7.0 (6.8 - 7.3) | 6.8 (6.6 - 7.0)
| Median LOS (discharge) | 6.0 (5.9 - 6.1) | 7.0 (6.8 - 7.1) | 8.8 (8.6 - 9.0)
Mar-21 |  |  |
| HFR | 17.3% (14.7 - 20.4%) | 24.1% (21.0 - 27.7%) | 34.9% (31.1 - 39.2%)
| Median LOS (death) | 10.3 (9.6 - 11.3) | 7.2 (6.9 - 7.7) | 7.6 (7.1 - 8.1)
| Median LOS (discharge) | 5.0 (4.8 - 5.2) | 6.2 (5.9 - 6.6) | 9.0 (8.5 - 9.4)
Apr-21 |  |  |
| HFR | 15.2% (11.0 - 21.1%) | 23.2% (18.1 - 29.8%) | 34.9% (28.2 - 43.2%)
| Median LOS (death) | 9.8 (8.8 - 10.8) | 7.8 (7.1 - 8.6) | 6.3 (5.1 - 8.2)
| Median LOS (discharge) | 5.6 (5.2 - 6.1) | 6.2 (5.8 - 6.7) | 7.8 (7.1 - 8.5)
May-21 |  |  |
| HFR | 24.2% (17.6 - 33.2%) | 24.0% (17.4 - 33.2%) | 27.8% (19.1 - 40.3%)
| Median LOS (death) | 11.0 (8.0 - 12.7) | 5.9 (5.0 - 6.5) | 9.6 (9.4 - 11.0)
| Median LOS (discharge) | 3.6 (3.2 - 4.1) | 7.3 (6.5 - 8.2) | 5.1 (4.4 - 5.8)
Jun-21 |  |  |
| HFR | 17.6% (13.7 - 22.7%) | 26.2% (21.4 - 32.2%) | 43.5% (36.4 - 51.9%)
| Median LOS (death) | 11.4 (11.1 - 12.1) | 9.0 (8.4 - 9.6) | 7.9 (7.4 - 8.7)
| Median LOS (discharge) | 4.9 (4.5 - 5.3) | 7.8 (7.0 - 8.6) | 9.5 (8.8 - 10.2)
Jul-21 |  |  |
| HFR | 18.4% (16.4 - 20.6%) | 25.7% (23.4 - 28.2%) | 35.4% (32.1 - 38.9%)
| Median LOS (death) | 9.7 (9.2 - 10.3) | 8.0 (7.7 - 8.4) | 8.6 (8.1 - 9.2)
| Median LOS (discharge) | 5.0 (4.8 - 5.2) | 5.8 (5.6 - 6.1) | 7.3 (6.8 - 7.8)
Aug-21 |  |  |
| HFR | 17.7% (16.0 - 19.5%) | 24.8% (22.9 - 26.7%) | 34.2% (31.6 - 37.1%)
| Median LOS (death) | 10.6 (10.2 - 11.0) | 7.6 (7.3 - 7.9) | 8.5 (8.1 - 8.8)
| Median LOS (discharge) | 4.8 (4.7 - 5.0) | 6.0 (5.8 - 6.2) | 7.4 (7.0 - 7.7)
Sep-21 |  |  |
| HFR | 15.2% (13.6 - 17.0%) | 21.8% (20.0 - 23.7%) | 31.1% (28.6 - 33.9%)
| Median LOS (death) | 7.6 (7.2 - 8.0) | 7.4 (7.1 - 7.6) | 6.8 (6.6 - 7.1)
| Median LOS (discharge) | 5.3 (5.1 - 5.4) | 5.5 (5.3 - 5.7) | 8.0 (7.6 - 8.4)

Table 7: * Supplementary table 4: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and sex (unadjusted for other covariates). Figures in brackets represent 95% confidence intervals. |  |  |
---|---|---|---
Month of hospital admission | Male | Female
Mar-20 |  |
| HFR | 43.7% (42.5 - 44.9%) | 35.2% (33.8 - 36.6%)
| Median LOS (death) | 5.8 (5.7 - 5.9) | 5.2 (5.0 - 5.3)
| Median LOS (discharge) | 6.1 (6.0 - 6.2) | 5.7 (5.5 - 5.8)
Apr-20 |  |
| HFR | 39.7% (38.8 - 40.5%) | 34.4% (33.4 - 35.3%)
| Median LOS (death) | 5.4 (5.3 - 5.4) | 5.0 (4.9 - 5.1)
| Median LOS (discharge) | 5.8 (5.8 - 5.9) | 5.8 (5.8 - 5.9)
May-20 |  |
| HFR | 31.9% (30.4 - 33.6%) | 27.4% (25.9 - 29.0%)
| Median LOS (death) | 6.5 (6.4 - 6.7) | 6.6 (6.4 - 6.8)
| Median LOS (discharge) | 5.9 (5.7 - 6.0) | 5.3 (5.1 - 5.4)
Jun-20 |  |
| HFR | 23.0% (20.7 - 25.5%) | 17.7% (15.7 - 19.9%)
| Median LOS (death) | 8.1 (7.8 - 8.6) | 7.3 (7.0 - 7.7)
| Median LOS (discharge) | 5.2 (5.0 - 5.4) | 4.7 (4.4 - 4.9)
Jul-20 |  |
| HFR | 15.1% (12.2 - 18.7%) | 11.2% (8.8 - 14.3%)
| Median LOS (death) | 11.5 (10.6 - 12.1) | 8.0 (7.5 - 9.0)
| Median LOS (discharge) | 4.9 (4.6 - 5.2) | 3.1 (2.8 - 3.4)
Aug-20 |  |
| HFR | 14.5% (11.5 - 18.4%) | 10.2% (7.7 - 13.5%)
| Median LOS (death) | 11.7 (9.8 - 12.6) | 8.2 (7.8 - 8.8)
| Median LOS (discharge) | 4.2 (3.8 - 4.5) | 2.5 (2.3 - 2.7)
Sep-20 |  |
| HFR | 18.4% (16.8 - 20.2%) | 12.1% (10.7 - 13.7%)
| Median LOS (death) | 9.7 (9.4 - 10.1) | 7.3 (6.9 - 7.9)
| Median LOS (discharge) | 4.6 (4.5 - 4.7) | 3.4 (3.2 - 3.5)
Oct-20 |  |
| HFR | 22.5% (21.6 - 23.5%) | 15.1% (14.3 - 16.0%)
| Median LOS (death) | 9.0 (8.8 - 9.2) | 7.7 (7.4 - 7.9)
| Median LOS (discharge) | 4.8 (4.7 - 4.9) | 4.1 (4.0 - 4.2)
Nov-20 |  |
| HFR | 23.6% (22.9 - 24.4%) | 17.5% (16.8 - 18.3%)
| Median LOS (death) | 8.7 (8.5 - 8.8) | 8.1 (7.9 - 8.2)
| Median LOS (discharge) | 5.2 (5.1 - 5.3) | 4.4 (4.4 - 4.5)
Dec-20 |  |
| HFR | 25.2% (24.5 - 25.9%) | 19.7% (19.1 - 20.4%)
| Median LOS (death) | 8.7 (8.6 - 8.8) | 8.2 (8.0 - 8.3)
| Median LOS (discharge) | 5.2 (5.2 - 5.3) | 4.9 (4.8 - 4.9)
Jan-21 |  |
| HFR | 25.2% (24.7 - 25.7%) | 20.2% (19.8 - 20.7%)
| Median LOS (death) | 7.9 (7.8 - 8.0) | 7.0 (6.9 - 7.1)
| Median LOS (discharge) | 5.0 (5.0 - 5.1) | 4.7 (4.7 - 4.8)
Feb-21 |  |
| HFR | 19.3% (18.5 - 20.1%) | 16.2% (15.5 - 17.0%)
| Median LOS (death) | 8.5 (8.4 - 8.7) | 6.9 (6.8 - 7.1)
| Median LOS (discharge) | 4.7 (4.7 - 4.8) | 4.4 (4.3 - 4.5)
Mar-21 |  |
| HFR | 12.0% (10.8 - 13.2%) | 9.0% (8.0 - 10.2%)
| Median LOS (death) | 9.6 (9.3 - 10.0) | 7.5 (7.1 - 7.9)
| Median LOS (discharge) | 4.0 (3.9 - 4.1) | 3.3 (3.2 - 3.4)
Apr-21 |  |
| HFR | 8.6% (6.9 - 10.6%) | 8.9% (7.2 - 10.9%)
| Median LOS (death) | 8.9 (8.5 - 9.4) | 8.3 (7.7 - 9.1)
| Median LOS (discharge) | 3.7 (3.5 - 3.9) | 2.7 (2.5 - 2.8)
May-21 |  |
| HFR | 8.8% (6.9 - 11.3%) | 8.4% (6.5 - 10.9%)
| Median LOS (death) | 11.3 (10.6 - 12.3) | 8.7 (7.4 - 9.9)
| Median LOS (discharge) | 3.2 (3.0 - 3.4) | 2.4 (2.2 - 2.5)
Jun-21 |  |
| HFR | 9.7% (8.4 - 11.2%) | 6.6% (5.5 - 7.8%)
| Median LOS (death) | 10.5 (10.2 - 11.0) | 10.3 (9.8 - 10.8)
| Median LOS (discharge) | 3.2 (3.1 - 3.4) | 2.2 (2.1 - 2.3)
Jul-21 |  |
| HFR | 11.2% (10.5 - 12.0%) | 6.4% (5.8 - 7.0%)
| Median LOS (death) | 10.6 (10.4 - 10.9) | 8.5 (8.2 - 8.8)
| Median LOS (discharge) | 3.6 (3.6 - 3.7) | 2.5 (2.4 - 2.6)
Aug-21 |  |
| HFR | 12.9% (12.2 - 13.8%) | 8.7% (8.1 - 9.3%)
| Median LOS (death) | 9.9 (9.7 - 10.1) | 9.1 (8.8 - 9.4)
| Median LOS (discharge) | 3.7 (3.7 - 3.8) | 2.8 (2.7 - 2.8)
Sep-21 |  |
| HFR | 13.1% (12.3 - 14.0%) | 8.1% (7.5 - 8.8%)
| Median LOS (death) | 8.0 (7.8 - 8.2) | 7.1 (6.9 - 7.3)
| Median LOS (discharge) | 4.0 (4.0 - 4.1) | 3.1 (3.0 - 3.2)

Table 8: * Supplementary table 5: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and ethnicity (unadjusted for other covariates). Figures in brackets represent 95% confidence intervals. |  |  |  |
---|---|---|---|---
Month of hospital admission | Asian | Black | White
Mar-20 |  |  |
| HFR | 36.7% (34.1 - 39.4%) | 35.8% (33.1 - 38.6%) | 42.3% (41.2 - 43.4%)
| Median LOS (death) | 5.6 (5.3 - 5.9) | 6.2 (5.9 - 6.5) | 5.4 (5.3 - 5.5)
| Median LOS (discharge) | 4.2 (4.1 - 4.4) | 5.9 (5.8 - 6.1) | 6.3 (6.2 - 6.4)
Apr-20 |  |  |
| HFR | 28.8% (27.0 - 30.7%) | 29.3% (27.1 - 31.8%) | 40.1% (39.3 - 40.8%)
| Median LOS (death) | 4.8 (4.6 - 5.0) | 4.8 (4.6 - 5.0) | 5.2 (5.2 - 5.3)
| Median LOS (discharge) | 4.1 (3.9 - 4.2) | 5.0 (4.8 - 5.1) | 6.3 (6.3 - 6.4)
May-20 |  |  |
| HFR | 16.9% (13.9 - 20.5%) | 19.8% (14.9 - 26.3%) | 31.8% (30.6 - 33.0%)
| Median LOS (death) | 5.5 (4.9 - 6.1) | 9.0 (7.9 - 10.5) | 6.5 (6.3 - 6.6)
| Median LOS (discharge) | 3.0 (2.8 - 3.2) | 5.1 (4.8 - 5.5) | 6.1 (5.9 - 6.2)
Jun-20 |  |  |
| HFR | 13.9% (10.9 - 17.8%) | 9.9% (4.9 - 19.9%) | 22.7% (20.8 - 24.6%)
| Median LOS (death) | 8.6 (8.3 - 8.9) | 5.3 (1.0 - 7.2) | 7.6 (7.3 - 7.9)
| Median LOS (discharge) | 2.8 (2.6 - 3.0) | 3.0 (2.5 - 3.5) | 6.0 (5.8 - 6.2)
Jul-20 |  |  |
| HFR | 12.6% (8.9 - 17.7%) | 9.9% (3.4 - 29.0%) | 13.4% (11.1 - 16.3%)
| Median LOS (death) | 11.8 (10.1 - 12.7) | 38.0 (14.0 - 38.8) | 9.3 (8.0 - 10.5)
| Median LOS (discharge) | 3.7 (3.4 - 4.0) | 2.5 (1.8 - 3.2) | 4.6 (4.3 - 4.9)
Aug-20 |  |  |
| HFR | 11.0% (7.7 - 15.7%) | 4.9% (1.9 - 12.8%) | 15.6% (12.6 - 19.3%)
| Median LOS (death) | 11.5 (11.0 - 13.0) | 7.5 (4.7 - 8.6) | 10.4 (9.8 - 11.3)
| Median LOS (discharge) | 3.1 (2.8 - 3.5) | 2.3 (1.8 - 2.9) | 3.3 (3.0 - 3.5)
Sep-20 |  |  |
| HFR | 13.5% (11.4 - 16.1%) | 7.1% (4.4 - 11.6%) | 17.5% (16.1 - 19.1%)
| Median LOS (death) | 9.9 (9.6 - 10.3) | 11.0 (9.6 - 17.3) | 8.5 (8.0 - 8.9)
| Median LOS (discharge) | 3.3 (3.1 - 3.5) | 3.8 (3.4 - 4.2) | 4.4 (4.3 - 4.6)
Oct-20 |  |  |
| HFR | 13.8% (12.3 - 15.5%) | 10.8% (8.3 - 14.0%) | 20.8% (20.1 - 21.6%)
| Median LOS (death) | 9.0 (8.5 - 9.5) | 8.4 (7.0 - 9.0) | 8.4 (8.2 - 8.6)
| Median LOS (discharge) | 3.6 (3.4 - 3.7) | 3.7 (3.4 - 4.0) | 4.8 (4.7 - 4.9)
Nov-20 |  |  |
| HFR | 14.8% (13.5 - 16.2%) | 11.7% (9.6 - 14.3%) | 22.5% (21.9 - 23.1%)
| Median LOS (death) | 8.2 (7.9 - 8.5) | 9.9 (9.5 - 11.4) | 8.4 (8.3 - 8.5)
| Median LOS (discharge) | 3.5 (3.4 - 3.6) | 4.5 (4.2 - 4.7) | 5.2 (5.1 - 5.2)
Dec-20 |  |  |
| HFR | 17.5% (16.3 - 18.7%) | 14.3% (12.7 - 16.0%) | 24.8% (24.2 - 25.4%)
| Median LOS (death) | 9.9 (9.6 - 10.2) | 10.2 (9.6 - 11.0) | 8.2 (8.1 - 8.3)
| Median LOS (discharge) | 3.9 (3.8 - 4.0) | 4.3 (4.1 - 4.4) | 5.5 (5.4 - 5.5)
Jan-21 |  |  |
| HFR | 18.3% (17.4 - 19.2%) | 15.9% (14.7 - 17.1%) | 24.8% (24.4 - 25.2%)
| Median LOS (death) | 9.4 (9.2 - 9.6) | 8.7 (8.4 - 9.0) | 7.3 (7.2 - 7.3)
| Median LOS (discharge) | 4.1 (4.0 - 4.2) | 4.3 (4.2 - 4.4) | 5.2 (5.2 - 5.3)
Feb-21 |  |  |
| HFR | 14.4% (13.0 - 15.9%) | 13.3% (11.2 - 15.9%) | 19.1% (18.5 - 19.8%)
| Median LOS (death) | 9.1 (8.8 - 9.5) | 9.0 (8.4 - 9.9) | 7.5 (7.4 - 7.7)
| Median LOS (discharge) | 3.6 (3.5 - 3.7) | 4.0 (3.9 - 4.2) | 4.9 (4.8 - 4.9)
Mar-21 |  |  |
| HFR | 8.7% (7.0 - 11.0%) | 5.4% (3.1 - 9.3%) | 11.6% (10.7 - 12.7%)
| Median LOS (death) | 11.0 (10.5 - 12.1) | 9.3 (5.8 - 14.3) | 8.3 (8.0 - 8.7)
| Median LOS (discharge) | 2.8 (2.6 - 3.0) | 2.9 (2.6 - 3.3) | 3.9 (3.8 - 4.0)
Apr-21 |  |  |
| HFR | 7.9% (5.6 - 11.2%) | 4.9% (1.6 - 14.8%) | 10.1% (8.5 - 11.9%)
| Median LOS (death) | 6.2 (6.0 - 6.7) | 4.0 (1.8 - 8.8) | 9.2 (8.8 - 9.7)
| Median LOS (discharge) | 2.7 (2.4 - 2.9) | 1.9 (1.4 - 2.4) | 3.5 (3.4 - 3.7)
May-21 |  |  |
| HFR | 9.8% (7.3 - 13.2%) | 7.0% (3.3 - 15.2%) | 9.2% (7.3 - 11.7%)
| Median LOS (death) | 10.3 (7.9 - 12.2) | 11.0 (5.3 - 14.4) | 9.2 (8.7 - 10.2)
| Median LOS (discharge) | 3.0 (2.8 - 3.3) | 2.3 (1.8 - 3.0) | 2.9 (2.8 - 3.2)
Jun-21 |  |  |
| HFR | 8.6% (6.7 - 11.2%) | 6.2% (4.1 - 9.5%) | 8.6% (7.5 - 9.8%)
| Median LOS (death) | 11.7 (10.8 - 12.7) | 10.5 (8.1 - 14.0) | 10.2 (9.8 - 10.5)
| Median LOS (discharge) | 2.7 (2.5 - 2.9) | 3.5 (3.0 - 3.9) | 2.6 (2.5 - 2.7)
Jul-21 |  |  |
| HFR | 8.4% (7.0 - 10.1%) | 8.0% (6.5 - 9.9%) | 9.3% (8.8 - 9.9%)
| Median LOS (death) | 12.1 (11.5 - 12.9) | 11.8 (11.3 - 12.3) | 9.7 (9.5 - 9.9)
| Median LOS (discharge) | 2.7 (2.6 - 2.9) | 3.9 (3.6 - 4.1) | 3.0 (2.9 - 3.0)
Aug-21 |  |  |
| HFR | 11.4% (9.9 - 13.1%) | 8.9% (7.4 - 10.7%) | 11.4% (10.8 - 12.0%)
| Median LOS (death) | 9.6 (9.1 - 10.2) | 10.8 (10.2 - 11.4) | 9.2 (9.0 - 9.5)
| Median LOS (discharge) | 2.9 (2.8 - 3.0) | 3.9 (3.8 - 4.1) | 3.3 (3.2 - 3.3)
Sep-21 |  |  |
| HFR | 9.3% (7.7 - 11.2%) | 8.3% (6.4 - 10.6%) | 11.5% (10.8 - 12.1%)
| Median LOS (death) | 8.6 (8.1 - 9.2) | 8.8 (8.4 - 9.9) | 7.5 (7.3 - 7.7)
| Median LOS (discharge) | 3.0 (2.8 - 3.2) | 4.0 (3.8 - 4.2) | 3.7 (3.6 - 3.7)

Table 9: * Supplementary table 6: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and region of residence (unadjusted for other covariates). Figures in brackets represent 95% confidence intervals. |  |  |  |
---|---|---|---|---
Month of hospital admission | London | East Midlands | East of England
Mar-20 |  |  |
| HFR | 40.8% (39.2 - 42.4%) | 33.9% (30.9 - 37.1%) | 42.5% (39.5 - 45.6%)
| Median LOS (death) | 5.8 (5.7 - 6.0) | 6.2 (5.9 - 6.5) | 5.8 (5.6 - 6.1)
| Median LOS (discharge) | 6.1 (5.9 - 6.2) | 6.0 (5.8 - 6.3) | 5.6 (5.4 - 5.8)
Apr-20 |  |  |
| HFR | 35.3% (34.0 - 36.7%) | 34.9% (32.7 - 37.1%) | 41.9% (40.1 - 43.8%)
| Median LOS (death) | 4.9 (4.8 - 5.0) | 5.0 (4.9 - 5.2) | 5.3 (5.1 - 5.4)
| Median LOS (discharge) | 5.4 (5.3 - 5.5) | 5.5 (5.4 - 5.7) | 5.9 (5.8 - 6.1)
May-20 |  |  |
| HFR | 19.4% (16.3 - 23.1%) | 28.4% (25.4 - 31.8%) | 29.2% (26.4 - 32.2%)
| Median LOS (death) | 8.6 (7.9 - 9.3) | 7.0 (6.6 - 7.4) | 5.9 (5.7 - 6.3)
| Median LOS (discharge) | 4.9 (4.5 - 5.2) | 6.6 (6.3 - 6.9) | 5.8 (5.5 - 6.0)
Jun-20 |  |  |
| HFR | 7.0% (4.3 - 11.3%) | 21.3% (17.5 - 25.8%) | 16.9% (13.3 - 21.4%)
| Median LOS (death) | 10.5 (10.3 - 12.2) | 7.8 (7.5 - 8.5) | 8.8 (8.4 - 10.0)
| Median LOS (discharge) | 3.3 (2.8 - 4.0) | 5.5 (5.2 - 5.8) | 4.6 (4.2 - 5.1)
Jul-20 |  |  |
| HFR | 6.3% (3.2 - 12.2%) | 10.6% (6.5 - 17.0%) | 8.1% (4.5 - 14.6%)
| Median LOS (death) | 13.5 (8.6 - 15.8) | 7.7 (4.9 - 9.6) | 5.0 (2.3 - 10.6)
| Median LOS (discharge) | 4.2 (3.0 - 5.1) | 4.2 (3.7 - 4.7) | 4.8 (4.1 - 5.4)
Aug-20 |  |  |
| HFR | 7.1% (3.6 - 13.8%) | 12.8% (7.0 - 23.6%) | 5.7% (1.9 - 17.2%)
| Median LOS (death) | 12.0 (6.6 - 18.8) | 12.0 (7.5 - 14.9) | 3.0 (1.5 - 3.8)
| Median LOS (discharge) | 2.9 (2.3 - 3.4) | 5.4 (4.9 - 5.8) | 2.7 (1.5 - 3.6)
Sep-20 |  |  |
| HFR | 9.6% (7.3 - 12.7%) | 10.9% (7.5 - 15.7%) | 13.8% (9.6 - 19.8%)
| Median LOS (death) | 10.7 (10.4 - 12.4) | 10.2 (8.3 - 10.9) | 11.0 (7.6 - 12.8)
| Median LOS (discharge) | 4.4 (4.1 - 4.7) | 4.0 (3.7 - 4.4) | 3.0 (2.7 - 3.4)
Oct-20 |  |  |
| HFR | 12.9% (11.3 - 14.8%) | 20.1% (18.0 - 22.4%) | 23.1% (20.3 - 26.3%)
| Median LOS (death) | 10.7 (9.5 - 11.5) | 8.4 (8.1 - 8.8) | 8.3 (7.6 - 8.8)
| Median LOS (discharge) | 4.4 (4.3 - 4.6) | 4.5 (4.4 - 4.7) | 4.4 (4.2 - 4.6)
Nov-20 |  |  |
| HFR | 15.7% (14.3 - 17.3%) | 21.9% (20.3 - 23.6%) | 20.3% (18.4 - 22.5%)
| Median LOS (death) | 9.5 (9.1 - 9.9) | 8.6 (8.3 - 8.9) | 9.3 (8.9 - 9.7)
| Median LOS (discharge) | 4.9 (4.8 - 5.0) | 4.9 (4.7 - 5.0) | 4.7 (4.6 - 4.9)
Dec-20 |  |  |
| HFR | 18.7% (17.8 - 19.6%) | 26.8% (25.1 - 28.7%) | 25.3% (23.9 - 26.7%)
| Median LOS (death) | 9.2 (9.0 - 9.4) | 9.1 (8.8 - 9.3) | 8.3 (8.0 - 8.5)
| Median LOS (discharge) | 4.6 (4.6 - 4.7) | 5.1 (5.0 - 5.3) | 5.1 (5.0 - 5.2)
Jan-21 |  |  |
| HFR | 19.8% (19.1 - 20.5%) | 24.5% (23.3 - 25.8%) | 26.5% (25.5 - 27.5%)
| Median LOS (death) | 7.9 (7.7 - 8.0) | 7.1 (6.9 - 7.3) | 6.8 (6.6 - 6.9)
| Median LOS (discharge) | 4.5 (4.4 - 4.5) | 5.2 (5.1 - 5.3) | 5.0 (4.9 - 5.0)
Feb-21 |  |  |
| HFR | 14.2% (12.9 - 15.7%) | 19.7% (18.0 - 21.6%) | 19.8% (18.2 - 21.7%)
| Median LOS (death) | 8.8 (8.5 - 9.3) | 7.7 (7.3 - 8.0) | 7.2 (6.9 - 7.6)
| Median LOS (discharge) | 4.1 (4.0 - 4.2) | 5.2 (5.1 - 5.4) | 4.7 (4.6 - 4.8)
Mar-21 |  |  |
| HFR | 8.2% (6.3 - 10.7%) | 11.6% (9.4 - 14.3%) | 13.7% (10.9 - 17.3%)
| Median LOS (death) | 12.2 (9.8 - 13.5) | 10.0 (9.1 - 11.2) | 10.5 (10.0 - 11.3)
| Median LOS (discharge) | 3.5 (3.3 - 3.7) | 4.1 (3.8 - 4.3) | 3.8 (3.5 - 4.0)
Apr-21 |  |  |
| HFR | 6.5% (3.9 - 10.8%) | 10.6% (7.0 - 16.1%) | 7.9% (4.8 - 13.0%)
| Median LOS (death) | 9.3 (4.4 - 12.5) | 6.7 (3.8 - 8.4) | 10.3 (5.8 - 11.7)
| Median LOS (discharge) | 2.4 (2.1 - 2.8) | 4.1 (3.6 - 4.5) | 4.2 (3.7 - 4.8)
May-21 |  |  |
| HFR | 7.2% (4.5 - 11.5%) | 5.7% (2.6 - 12.5%) | 6.7% (3.4 - 13.1%)
| Median LOS (death) | 17.0 (9.6 - 20.7) | 13.0 (2.4 - 13.4) | 16.5 (4.6 - 19.4)
| Median LOS (discharge) | 3.7 (3.3 - 4.0) | 2.8 (2.4 - 3.3) | 2.9 (2.5 - 3.3)
Jun-21 |  |  |
| HFR | 8.6% (6.6 - 11.2%) | 8.9% (5.7 - 13.8%) | 6.5% (3.9 - 10.8%)
| Median LOS (death) | 11.3 (10.7 - 12.9) | 8.0 (7.8 - 12.2) | 8.5 (5.9 - 11.0)
| Median LOS (discharge) | 2.9 (2.7 - 3.1) | 2.7 (2.4 - 2.9) | 2.6 (2.3 - 2.9)
Jul-21 |  |  |
| HFR | 7.7% (6.7 - 9.0%) | 8.4% (6.8 - 10.3%) | 8.3% (6.8 - 10.2%)
| Median LOS (death) | 11.8 (11.4 - 12.4) | 9.5 (8.9 - 10.4) | 11.5 (10.6 - 12.2)
| Median LOS (discharge) | 3.3 (3.2 - 3.5) | 3.4 (3.2 - 3.6) | 2.5 (2.4 - 2.7)
Aug-21 |  |  |
| HFR | 9.5% (8.4 - 10.8%) | 11.5% (10.0 - 13.3%) | 10.1% (8.6 - 11.9%)
| Median LOS (death) | 10.8 (10.5 - 11.2) | 9.4 (9.1 - 9.9) | 8.6 (8.3 - 9.2)
| Median LOS (discharge) | 3.6 (3.5 - 3.7) | 3.6 (3.4 - 3.7) | 3.0 (2.9 - 3.2)
Sep-21 |  |  |
| HFR | 9.4% (8.1 - 11.0%) | 12.2% (10.5 - 14.2%) | 11.0% (9.2 - 13.2%)
| Median LOS (death) | 8.9 (8.5 - 9.4) | 8.2 (7.7 - 8.7) | 6.7 (6.4 - 7.1)
| Median LOS (discharge) | 3.9 (3.8 - 4) | 3.7 (3.6 - 3.9) | 3.4 (3.2 - 3.5)
Table 10: * Supplementary table 6 continued |  |  |  |
---|---|---|---|---
Month of hospital admission | North East | North West | South East
Mar-20 |  |  |
| HFR | 38.2% (32.3 - 45.2%) | 41.4% (38.9 - 44.0%) | 38.2% (35.7 - 41.0%)
| Median LOS (death) | 5.3 (5.0 - 5.7) | 5.3 (5.1 - 5.6) | 5.3 (5.0 - 5.5)
| Median LOS (discharge) | 6.6 (6.2 - 7.1) | 6.3 (6.1 - 6.5) | 6.2 (6.0 - 6.4)
Apr-20 |  |  |
| HFR | 36.5% (34.1 - 39.1%) | 38.8% (37.3 - 40.3%) | 34.7% (33.0 - 36.5%)
| Median LOS (death) | 4.9 (4.7 - 5.1) | 5.3 (5.2 - 5.5) | 5.5 (5.3 - 5.6)
| Median LOS (discharge) | 5.9 (5.8 - 6.1) | 6.1 (6.0 - 6.2) | 5.9 (5.8 - 6.1)
May-20 |  |  |
| HFR | 39.4% (34.7 - 44.7%) | 30.7% (28.3 - 33.3%) | 28.6% (25.5 - 31.9%)
| Median LOS (death) | 7.2 (6.7 - 7.7) | 5.9 (5.6 - 6.2) | 6.4 (6.0 - 6.8)
| Median LOS (discharge) | 4.3 (3.9 - 4.7) | 5.7 (5.5 - 6.0) | 5.7 (5.4 - 5.9)
Jun-20 |  |  |
| HFR | 17.8% (11.3 - 28.1%) | 24.8% (21.2 - 28.9%) | 21.8% (17.4 - 27.1%)
| Median LOS (death) | 7.0 (4.8 - 14.0) | 6.7 (6.3 - 7.5) | 7.0 (6.6 - 7.6)
| Median LOS (discharge) | 4.7 (3.6 - 6.6) | 5.3 (4.9 - 5.7) | 5.4 (4.9 - 5.8)
Jul-20 |  |  |
| HFR | 10.0% (2.7 - 37.2%) | 17.1% (12.6 - 23.4%) | 21.1% (14.9 - 29.8%)
| Median LOS (death) | 9.5 (2.6 - 13.3) | 10.3 (10.1 - 10.8) | 7.0 (6.3 - 9.9)
| Median LOS (discharge) | 5.5 (3.6 - 8.1) | 4.0 (3.5 - 4.5) | 3.8 (3.4 - 4.7)
Aug-20 |  |  |
| HFR | 17.6% (6.3 - 49.3%) | 16.1% (12.1 - 21.4%) | 14.0% (7.0 - 27.8%)
| Median LOS (death) | 6.0 (1.4 - 7.2) | 7.8 (7.5 - 9.4) | 7.0 (3.9 - 7.8)
| Median LOS (discharge) | 2.5 (1.3 - 4.9) | 2.8 (2.5 - 3.1) | 5.0 (3.8 - 6.0)
Sep-20 |  |  |
| HFR | 19.8% (16.3 - 24.1%) | 19.3% (17.2 - 21.7%) | 14.7% (10.3 - 20.9%)
| Median LOS (death) | 6.6 (5.6 - 7.3) | 8.7 (8.3 - 9.2) | 7.5 (5.2 - 10.7)
| Median LOS (discharge) | 3.6 (3.3 - 3.9) | 4.9 (4.8 - 5.1) | 4.3 (3.9 - 4.7)
Oct-20 |  |  |
| HFR | 19.7% (17.7 - 22.0%) | 21.2% (20.0 - 22.4%) | 15.1% (12.8 - 17.8%)
| Median LOS (death) | 7.4 (7.0 - 7.8) | 7.8 (7.6 - 8.1) | 8.5 (8.0 - 9.2)
| Median LOS (discharge) | 4.3 (4.1 - 4.5) | 4.7 (4.6 - 4.8) | 4.3 (4.1 - 4.5)
Nov-20 |  |  |
| HFR | 20.0% (18.2 - 22.0%) | 23.7% (22.5 - 25.1%) | 19.8% (18.2 - 21.6%)
| Median LOS (death) | 7.0 (6.8 - 7.4) | 8.1 (7.9 - 8.3) | 8.7 (8.4 - 9.0)
| Median LOS (discharge) | 4.6 (4.4 - 4.8) | 4.9 (4.9 - 5.1) | 5.1 (4.9 - 5.2)
Dec-20 |  |  |
| HFR | 22.7% (20.5 - 25.1%) | 24.2% (22.7 - 25.8%) | 22.1% (21.0 - 23.2%)
| Median LOS (death) | 7.4 (7.1 - 7.9) | 7.7 (7.5 - 8.0) | 9.0 (8.8 - 9.3)
| Median LOS (discharge) | 5.3 (5.1 - 5.4) | 5.2 (5.1 - 5.3) | 5.3 (5.2 - 5.3)
Jan-21 |  |  |
| HFR | 22.2% (20.6 - 23.9%) | 24.4% (23.4 - 25.4%) | 23.5% (22.6 - 24.3%)
| Median LOS (death) | 8.1 (7.8 - 8.4) | 7.9 (7.7 - 8.1) | 7.7 (7.5 - 7.9)
| Median LOS (discharge) | 4.7 (4.6 - 4.8) | 5.1 (5.0 - 5.2) | 5.0 (4.9 - 5.0)
Feb-21 |  |  |
| HFR | 15.3% (13.4 - 17.6%) | 19.7% (18.4 - 21.2%) | 17.0% (15.6 - 18.6%)
| Median LOS (death) | 7.0 (6.4 - 7.6) | 7.6 (7.4 - 7.9) | 8.5 (8.1 - 8.9)
| Median LOS (discharge) | 4.2 (4.0 - 4.4) | 4.6 (4.5 - 4.8) | 4.8 (4.7 - 4.9)
Mar-21 |  |  |
| HFR | 7.0% (4.9 - 10.1%) | 11.5% (9.7 - 13.6%) | 9.7% (7.5 - 12.6%)
| Median LOS (death) | 10.2 (10.0 - 11.0) | 7.3 (6.7 - 7.9) | 8.0 (7.4 - 9.2)
| Median LOS (discharge) | 3.0 (2.8 - 3.4) | 3.7 (3.5 - 3.9) | 4.0 (3.8 - 4.3)
Apr-21 |  |  |
| HFR | 5.1% (2.2 - 12.0%) | 10.3% (7.3 - 14.4%) | 3.4% (1.6 - 7.6%)
| Median LOS (death) | 7.0 (5.5 - 10.4) | 6.3 (5.9 - 7.4) | 10.0 (4.1 - 10.4)
| Median LOS (discharge) | 1.5 (1.2 - 1.9) | 3.4 (3.1 - 3.6) | 3.6 (3.2 - 4.0)
May-21 |  |  |
| HFR | 11.8% (5.6 - 25.1%) | 10.1% (7.3 - 14.0%) | 5.2% (2.0 - 13.5%)
| Median LOS (death) | 3.5 (2.1 - 4.1) | 9.0 (8.2 - 10.2) | 14.5 (6.9 - 17.3)
| Median LOS (discharge) | 3.2 (2.9 - 3.5) | 2.9 (2.6 - 3.1) | 2.7 (2.3 - 3.2)
Jun-21 |  |  |
| HFR | 5.2% (3.0 - 8.8%) | 9.9% (8.3 - 11.7%) | 5.1% (2.8 - 9.0%)
| Median LOS (death) | 7.0 (5.3 - 10.5) | 10.8 (10.4 - 11.4) | 8.0 (3.6 - 9.4)
| Median LOS (discharge) | 2.2 (1.9 - 2.4) | 2.5 (2.3 - 2.6) | 2.9 (2.5 - 3.2)
Jul-21 |  |  |
| HFR | 9.0% (7.6 - 10.6%) | 11.6% (10.4 - 13.0%) | 8.7% (7.3 - 10.4%)
| Median LOS (death) | 8.6 (7.9 - 9.2) | 9.5 (9.2 - 9.9) | 10.1 (9.8 - 10.8)
| Median LOS (discharge) | 2.6 (2.5 - 2.7) | 3.4 (3.3 - 3.5) | 2.8 (2.6 - 2.9)
Aug-21 |  |  |
| HFR | 10.5% (8.7 - 12.6%) | 11.9% (10.7 - 13.4%) | 10.0% (8.6 - 11.6%)
| Median LOS (death) | 9.5 (8.3 - 10.4) | 10.0 (9.5 - 10.4) | 9.3 (8.7 - 10.3)
| Median LOS (discharge) | 2.7 (2.6 - 2.9) | 3.1 (3.0 - 3.3) | 3.0 (2.9 - 3.2)
Sep-21 |  |  |
| HFR | 12.9% (10.9 - 15.3%) | 10.5% (9.2 - 12.0%) | 9.1% (7.7 - 10.9%)
| Median LOS (death) | 7.5 (7.2 - 7.8) | 7.2 (6.9 - 7.6) | 8.6 (8.3 - 9.0)
| Median LOS (discharge) | 3.3 (3.2 - 3.5) | 3.6 (3.4 - 3.7) | 3.5 (3.3 - 3.7)
Table 11: * Supplementary table 6 continued |  |  |  |
---|---|---|---|---
Month of hospital admission | South West | West Midlands | Yorkshire and Humber
Mar-20 |  |  |
| HFR | 37.6% (33.8 - 41.8%) | 42.0% (39.4 - 44.7%) | 45.6% (41.8 - 49.6%)
| Median LOS (death) | 5.5 (5.2 - 5.9) | 5.1 (4.9 - 5.3) | 5.5 (5.2 - 5.9)
| Median LOS (discharge) | 5.2 (4.9 - 5.6) | 4.7 (4.5 - 4.9) | 6.3 (6.0 - 6.5)
Apr-20 |  |  |
| HFR | 30.4% (28.1 - 33.0%) | 39.0% (37.1 - 41.0%) | 41.5% (39.6 - 43.6%)
| Median LOS (death) | 5.3 (5.1 - 5.5) | 5.3 (5.1 - 5.5) | 5.4 (5.2 - 5.6)
| Median LOS (discharge) | 5.9 (5.7 - 6.1) | 6.3 (6.1 - 6.4) | 5.9 (5.8 - 6.1)
May-20 |  |  |
| HFR | 24.5% (20.6 - 29.0%) | 30.6% (27.4 - 34.1%) | 34.7% (31.7 - 38.0%)
| Median LOS (death) | 6.1 (5.5 - 6.9) | 6.6 (6.3 - 7.0) | 6.8 (6.5 - 7.2)
| Median LOS (discharge) | 5.2 (4.7 - 5.8) | 6.1 (5.8 - 6.4) | 4.7 (4.5 - 4.9)
Jun-20 |  |  |
| HFR | 12.3% (7.4 - 20.4%) | 20.7% (16.3 - 26.2%) | 26.9% (22.3 - 32.3%)
| Median LOS (death) | 10.0 (3.8 - 13.1) | 7.4 (6.4 - 8.2) | 8.0 (7.5 - 8.8)
| Median LOS (discharge) | 3.9 (3.3 - 4.8) | 6.0 (5.5 - 6.6) | 4.0 (3.7 - 4.4)
Jul-20 |  |  |
| HFR | 5.8% (1.5 - 22.2%) | 10.7% (6.3 - 18.2%) | 18.7% (12.9 - 27.0%)
| Median LOS (death) | 3.0 (1.4 - 3.9) | 12.5 (7.6 - 14.6) | 12.7 (12.3 - 13.6)
| Median LOS (discharge) | 3.6 (2.7 - 4.2) | 3.5 (3.1 - 3.9) | 3.6 (3.0 - 4.2)
Aug-20 |  |  |
| HFR | 9.6% (3.8 - 24.4%) | 8.5% (4.7 - 15.4%) | 15.1% (10.2 - 22.4%)
| Median LOS (death) | 9.3 (6.1 - 9.6) | 12.5 (6.6 - 13.5) | 14.5 (14.1 - 15.5)
| Median LOS (discharge) | 3.0 (2.1 - 3.7) | 2.8 (2.3 - 3.3) | 3.1 (2.8 - 3.5)
Sep-20 |  |  |
| HFR | 7.3% (3.4 - 15.7%) | 13.7% (11.2 - 16.8%) | 14.8% (11.9 - 18.3%)
| Median LOS (death) | 9.0 (1.8 - 14.2) | 9.6 (8.6 - 10.3) | 9.5 (8.9 - 10.4)
| Median LOS (discharge) | 5.3 (4.8 - 5.7) | 3.8 (3.5 - 4.0) | 2.8 (2.6 - 3.1)
Oct-20 |  |  |
| HFR | 14.0% (11.6 - 16.8%) | 19.1% (17.3 - 21.1%) | 19.4% (17.8 - 21.1%)
| Median LOS (death) | 9.0 (8.7 - 9.4) | 9.5 (9.2 - 9.9) | 9.2 (8.7 - 9.7)
| Median LOS (discharge) | 4.8 (4.6 - 5.1) | 4.4 (4.2 - 4.5) | 4.4 (4.3 - 4.5)
Nov-20 |  |  |
| HFR | 16.2% (14.5 - 18.0%) | 21.9% (20.5 - 23.4%) | 22.1% (20.7 - 23.6%)
| Median LOS (death) | 8.7 (8.5 - 8.9) | 8.5 (8.2 - 8.8) | 8.2 (7.9 - 8.5)
| Median LOS (discharge) | 4.2 (4.0 - 4.4) | 5.1 (5.0 - 5.3) | 4.7 (4.6 - 4.8)
Dec-20 |  |  |
| HFR | 17.5% (15.8 - 19.4%) | 24.2% (22.7 - 25.8%) | 26.7% (24.8 - 28.7%)
| Median LOS (death) | 9.0 (8.7 - 9.4) | 7.5 (7.3 - 7.8) | 7.4 (7.1 - 7.8)
| Median LOS (discharge) | 5.4 (5.2 - 5.6) | 5.5 (5.4 - 5.6) | 4.8 (4.7 - 5.0)
Jan-21 |  |  |
| HFR | 19.2% (18.1 - 20.4%) | 23.7% (22.7 - 24.8%) | 21.8% (20.4 - 23.2%)
| Median LOS (death) | 6.9 (6.7 - 7.1) | 7.7 (7.5 - 7.8) | 8.2 (7.9 - 8.5)
| Median LOS (discharge) | 5.2 (5.1 - 5.3) | 5.2 (5.2 - 5.3) | 4.8 (4.7 - 5.0)
Feb-21 |  |  |
| HFR | 15.9% (14.0 - 17.9%) | 19.0% (17.5 - 20.5%) | 17.6% (15.9 - 19.5%)
| Median LOS (death) | 6.4 (6.2 - 6.7) | 8.4 (8.0 - 8.8) | 7.6 (7.4 - 8.0)
| Median LOS (discharge) | 4.8 (4.6 - 4.9) | 4.6 (4.5 - 4.7) | 4.4 (4.3 - 4.6)
Mar-21 |  |  |
| HFR | 8.0% (5.5 - 11.5%) | 12.8% (10.5 - 15.6%) | 9.8% (8.0 - 11.9%)
| Median LOS (death) | 6.8 (6.7 - 7.9) | 8.1 (7.5 - 8.6) | 8.4 (8.1 - 8.9)
| Median LOS (discharge) | 3.8 (3.5 - 4.1) | 3.6 (3.4 - 3.9) | 3.3 (3.1 - 3.5)
Apr-21 |  |  |
| HFR | 14.9% (9.0 - 24.5%) | 9.9% (6.6 - 15.1%) | 9.5% (7.0 - 12.9%)
| Median LOS (death) | 12.0 (11.9 - 13.2) | 9.0 (7.4 - 10.8) | 8.3 (7.9 - 9.4)
| Median LOS (discharge) | 4.4 (4.1 - 4.7) | 2.8 (2.5 - 3.1) | 3.0 (2.8 - 3.2)
May-21 |  |  |
| HFR | 10.1% (4.0 - 25.6%) | 9.2% (5.7 - 14.9%) | 10.3% (6.8 - 15.5%)
| Median LOS (death) | 10.5 (6.7 - 13.6) | 9.7 (8.2 - 11.6) | 8.0 (4.0 - 9.0)
| Median LOS (discharge) | 1.0 (0.9 - 1.7) | 2.8 (2.4 - 3.3) | 1.9 (1.7 - 2.2)
Jun-21 |  |  |
| HFR | 3.7% (1.8 - 7.6%) | 8.6% (6.2 - 12.1%) | 7.3% (5.0 - 10.6%)
| Median LOS (death) | 10.0 (1.8 - 10.8) | 9.0 (6.7 - 11.0) | 11.3 (9.9 - 12.2)
| Median LOS (discharge) | 2.6 (2.1 - 3.0) | 3.0 (2.7 - 3.3) | 3.1 (2.8 - 3.4)
Jul-21 |  |  |
| HFR | 5.8% (4.5 - 7.4%) | 8.3% (7.1 - 9.8%) | 8.4% (7.2 - 9.9%)
| Median LOS (death) | 8.6 (7.7 - 9.3) | 10.7 (10.2 - 11.6) | 9.3 (8.6 - 9.9)
| Median LOS (discharge) | 2.7 (2.6 - 2.9) | 3.0 (2.9 - 3.1) | 3.2 (3.0 - 3.3)
Aug-21 |  |  |
| HFR | 9.7% (8.3 - 11.4%) | 10.6% (9.2 - 12.2%) | 12.1% (10.7 - 13.7%)
| Median LOS (death) | 7.6 (7.1 - 8.6) | 10.0 (9.6 - 10.6) | 9.3 (8.9 - 9.8)
| Median LOS (discharge) | 3.1 (2.9 - 3.2) | 3.3 (3.2 - 3.4) | 3.2 (3.1 - 3.4)
Sep-21 |  |  |
| HFR | 9.9% (8.4 - 11.8%) | 11.0% (9.5 - 12.7%) | 9.9% (8.5 - 11.6%)
| Median LOS (death) | 6.8 (6.5 - 7.1) | 7.4 (7.0 - 8.0) | 7.4 (7.1 - 7.9)
| Median LOS (discharge) | 2.9 (2.8 - 3.1) | 3.8 (3.7 - 4.0) | 3.6 (3.5 - 3.8)

Table 12: * Supplementary table 7: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and Charleson Comorbidity Index (unadjusted for other covariates). Figures in brackets represent 95% confidence intervals. |  |  |  |  |
---|---|---|---|---|---
| Month of hospital
---
admission
0 | 1-2 | 3-4 | 5+
Mar-20 |  |  |  |
| HFR | 17.4% (16.1 - 18.8%) | 36.3% (35.0 - 37.8%) | 53.4% (51.1 - 55.8%) | 53.3% (50.0 - 56.8%)
| Median LOS (death) | 6.0 (5.8 - 6.3) | 5.6 (5.5 - 5.8) | 4.9 (4.8 - 5.1) | 5.0 (4.8 - 5.3)
| Median LOS (discharge) | 4.4 (4.3 - 4.5) | 6.4 (6.3 - 6.5) | 8.2 (8.0 - 8.4) | 8.3 (8.0 - 8.6)
Apr-20 |  |  |  |
| HFR | 15.2% (14.4 - 16.2%) | 34.4% (33.5 - 35.4%) | 48.1% (46.6 - 49.6%) | 52.4% (50.2 - 54.7%)
| Median LOS (death) | 5.6 (5.5 - 5.7) | 5.1 (5.0 - 5.2) | 4.9 (4.8 - 5.0) | 4.6 (4.5 - 4.8)
| Median LOS (discharge) | 4.3 (4.2 - 4.3) | 6.2 (6.1 - 6.2) | 7.9 (7.8 - 8.0) | 8.2 (8.0 - 8.4)
May-20 |  |  |  |
| HFR | 7.3% (6.2 - 8.7%) | 26.0% (24.3 - 27.7%) | 36.5% (34.0 - 39.2%) | 45.1% (41.6 - 49.0%)
| Median LOS (death) | 6.6 (6.3 - 7.1) | 6.0 (5.8 - 6.2) | 6.0 (5.8 - 6.3) | 6.6 (6.2 - 7.0)
| Median LOS (discharge) | 2.8 (2.7 - 2.9) | 6.3 (6.2 - 6.4) | 8.3 (8.1 - 8.6) | 7.4 (7.0 - 7.8)
Jun-20 |  |  |  |
| HFR | 3.9% (2.8 - 5.6%) | 18.3% (16.0 - 21.0%) | 28.7% (25.0 - 33.0%) | 36.6% (31.2 - 42.8%)
| Median LOS (death) | 8.5 (7.3 - 9.2) | 7.4 (7.0 - 7.8) | 6.9 (6.5 - 7.4) | 6.9 (6.4 - 7.6)
| Median LOS (discharge) | 2.3 (2.1 - 2.5) | 5.3 (5.1 - 5.6) | 8.3 (7.9 - 8.7) | 7.6 (7.2 - 7.9)
Jul-20 |  |  |  |
| HFR | 3.3% (1.9 - 5.7%) | 12.6% (9.6 - 16.6%) | 20.1% (14.6 - 27.7%) | 25.8% (19.1 - 34.8%)
| Median LOS (death) | 9.5 (5.4 - 11.6) | 8.0 (7.5 - 9.5) | 9.0 (8.5 - 10.1) | 12.5 (9.4 - 14.7)
| Median LOS (discharge) | 1.9 (1.8 - 2.2) | 4.4 (4.1 - 4.8) | 7.0 (6.3 - 7.7) | 9.0 (8.0 - 9.7)
Aug-20 |  |  |  |
| HFR | 2.6% (1.4 - 4.8%) | 11.7% (8.5 - 15.9%) | 26.9% (19.7 - 36.7%) | 34.7% (23.6 - 50.9%)
| Median LOS (death) | 12.0 (12.2 - 13.2) | 7.8 (7.6 - 8.6) | 10.7 (8.6 - 11.8) | 8.0 (5.7 - 10.3)
| Median LOS (discharge) | 1.6 (1.4 - 1.8) | 4.7 (4.2 - 5.1) | 7.0 (6.3 - 8.7) | 6.7 (5.5 - 8.1)
Sep-20 |  |  |  |
| HFR | 4.3% (3.4 - 5.4%) | 14.6% (12.9 - 16.4%) | 31.7% (28.0 - 36.0%) | 45.7% (39.7 - 52.6%)
| Median LOS (death) | 11.5 (10.6 - 12.6) | 9.7 (9.3 - 10.1) | 8.9 (8.0 - 9.4) | 5.8 (4.9 - 6.7)
| Median LOS (discharge) | 2.6 (2.4 - 2.7) | 5.0 (4.8 - 5.2) | 7.2 (6.8 - 7.6) | 6.8 (6.5 - 7.1)
Oct-20 |  |  |  |
| HFR | 5.4% (4.8 - 6.0%) | 19.4% (18.4 - 20.4%) | 34.3% (32.3 - 36.3%) | 41.7% (38.8 - 44.9%)
| Median LOS (death) | 11.2 (10.9 - 11.6) | 8.9 (8.7 - 9.1) | 7.4 (7.1 - 7.6) | 7.2 (6.9 - 7.6)
| Median LOS (discharge) | 2.9 (2.9 - 3.0) | 5.2 (5.1 - 5.3) | 7.2 (7.0 - 7.5) | 8.1 (7.8 - 8.3)
Nov-20 |  |  |  |
| HFR | 6.1% (5.6 - 6.7%) | 20.0% (19.2 - 20.9%) | 36.0% (34.5 - 37.6%) | 40.9% (38.7 - 43.3%)
| Median LOS (death) | 10.9 (10.5 - 11.2) | 8.6 (8.4 - 8.8) | 7.7 (7.5 - 7.9) | 7.5 (7.2 - 7.7)
| Median LOS (discharge) | 3.1 (3.0 - 3.1) | 5.6 (5.5 - 5.7) | 7.9 (7.7 - 8.0) | 8.0 (7.8 - 8.2)
Dec-20 |  |  |  |
| HFR | 6.7% (6.2 - 7.2%) | 22.4% (21.6 - 23.1%) | 38.7% (37.3 - 40.2%) | 47.3% (45.3 - 49.4%)
| Median LOS (death) | 10.6 (10.3 - 11.0) | 8.7 (8.5 - 8.8) | 7.9 (7.7 - 8.1) | 7.0 (6.8 - 7.2)
| Median LOS (discharge) | 3.4 (3.3 - 3.4) | 6.0 (5.9 - 6.1) | 8.4 (8.2 - 8.5) | 8.9 (8.7 - 9.0)
Jan-21 |  |  |  |
| HFR | 7.9% (7.5 - 8.2%) | 22.8% (22.3 - 23.3%) | 39.6% (38.5 - 40.6%) | 46.3% (44.8 - 47.9%)
| Median LOS (death) | 9.7 (9.5 - 9.9) | 7.5 (7.4 - 7.6) | 6.8 (6.7 - 6.9) | 6.6 (6.5 - 6.8)
| Median LOS (discharge) | 3.6 (3.6 - 3.6) | 5.7 (5.6 - 5.7) | 7.9 (7.8 - 8.1) | 8.0 (7.9 - 8.2)
Feb-21 |  |  |  |
| HFR | 5.5% (5.0 - 6.1%) | 17.4% (16.5 - 18.2%) | 32.6% (30.9 - 34.5%) | 39.1% (36.6 - 41.7%)
| Median LOS (death) | 10.3 (10.0 - 10.7) | 8.0 (7.8 - 8.3) | 7.1 (6.9 - 7.4) | 6.7 (6.5 - 7.0)
| Median LOS (discharge) | 3.0 (3.0 - 3.1) | 5.4 (5.3 - 5.5) | 7.6 (7.4 - 7.8) | 7.9 (7.7 - 8.2)
Mar-21 |  |  |  |
| HFR | 1.9% (1.4 - 2.5%) | 10.8% (9.5 - 12.2%) | 24.3% (21.3 - 27.8%) | 36.0% (31.3 - 41.3%)
| Median LOS (death) | 12.4 (12.1 - 13.8) | 8.9 (8.6 - 9.4) | 7.3 (7.0 - 7.7) | 8.1 (7.5 - 9.5)
| Median LOS (discharge) | 2.4 (2.3 - 2.5) | 4.5 (4.4 - 4.7) | 6.8 (6.4 - 7.1) | 7.1 (6.8 - 7.6)
Apr-21 |  |  |  |
| HFR | 1.1% (0.6 - 2.0%) | 9.1% (7.0 - 11.8%) | 21.8% (17.1 - 27.9%) | 26.9% (20.3 - 35.5%)
| Median LOS (death) | 8.5 (8.5 - 8.9) | 9.3 (7.3 - 10.5) | 7.4 (6.1 - 8.5) | 9.3 (9.1 - 10.0)
| Median LOS (discharge) | 2.0 (1.9 - 2.2) | 3.9 (3.6 - 4.1) | 6.2 (5.8 - 6.7) | 6.6 (6.3 - 7.1)
May-21 |  |  |  |
| HFR | 1.3% (0.7 - 2.4%) | 11.5% (8.7 - 15.4%) | 23.8% (16.8 - 33.7%) | 35.1% (25.9 - 47.5%)
| Median LOS (death) | 10.0 (6.9 - 11.9) | 16.3 (15.3 - 18.9) | 5.3 (4.1 - 5.8) | 9.2 (7.4 - 10.7)
| Median LOS (discharge) | 2.2 (2.0 - 2.4) | 3.4 (3.1 - 3.7) | 6.8 (5.7 - 8.1) | 7.3 (6.8 - 7.9)
Jun-21 |  |  |  |
| HFR | 1.8% (1.4 - 2.5%) | 11.1% (9.3 - 13.3%) | 28.1% (23.3 - 34.0%) | 28.4% (22.0 - 36.7%)
| Median LOS (death) | 13.5 (11.4 - 15.7) | 10.6 (10.3 - 11.1) | 10.2 (9.7 - 11.0) | 7.7 (7.0 - 9.1)
| Median LOS (discharge) | 2.0 (1.9 - 2.1) | 3.8 (3.6 - 4.0) | 7.6 (6.9 - 8.3) | 8.5 (7.2 - 9.7)
Jul-21 |  |  |  |
| HFR | 2.2% (1.9 - 2.5%) | 11.0% (10.1 - 12.0%) | 25.9% (23.4 - 28.5%) | 30.6% (27.0 - 34.7%)
| Median LOS (death) | 11.7 (11.4 - 12.2) | 10.2 (9.9 - 10.5) | 8.1 (7.6 - 8.7) | 8.9 (8.5 - 9.5)
| Median LOS (discharge) | 2.1 (2.1 - 2.2) | 4.3 (4.2 - 4.4) | 6.5 (6.2 - 6.8) | 6.5 (6.2 - 6.9)
Aug-21 |  |  |  |
| HFR | 2.7% (2.4 - 3.1%) | 12.1% (11.2 - 13.0%) | 26.4% (24.4 - 28.6%) | 29.4% (26.4 - 32.8%)
| Median LOS (death) | 12.7 (12.3 - 13.1) | 9.4 (9.1 - 9.7) | 8.1 (7.8 - 8.5) | 9.1 (8.5 - 9.7)
| Median LOS (discharge) | 2.2 (2.1 - 2.2) | 4.2 (4.1 - 4.3) | 6.4 (6.2 - 6.7) | 7.0 (6.7 - 7.3)
Sep-21 |  |  |  |
| HFR | 2.4% (2.0 - 2.8%) | 10.5% (9.6 - 11.5%) | 24.6% (22.6 - 26.9%) | 26.8% (23.8 - 30.1%)
| Median LOS (death) | 8.3 (8.1 - 8.7) | 7.8 (7.6 - 8.1) | 7.0 (6.8 - 7.3) | 7.5 (7.1 - 7.9)
| Median LOS (discharge) | 2.2 (2.2 - 2.3) | 4.4 (4.3 - 4.5) | 6.7 (6.5 - 6.9) | 6.8 (6.6 - 7.0)

Table 13: * Supplementary table 8: Hospitalised fatality risk and median length of stay (days) in hospital prior to death or discharge by month of hospital admission and measure of hospital load (unadjusted for other covariates). Estimates are replaced with a dash (-) where insufficient information was available. Figures in brackets represent 95% confidence intervals. |  |  |  |
---|---|---|---|---
Month of hospital admission | (0,20] | (20,40] | (40,60]
Mar-20 |  |  |
| HFR | 38.8% (36.6 - 41.0%) | 40.1% (38.5 - 41.7%) | 40.0% (38.3 - 41.9%)
| Median LOS (death) | 6.1 (5.9 - 6.2) | 5.7 (5.6 - 5.9) | 5.2 (5.1 - 5.4)
| Median LOS (discharge) | 5.6 (5.5 - 5.8) | 6.0 (5.9 - 6.1) | 6.0 (5.9 - 6.2)
Apr-20 |  |  |
| HFR | 34.3% (32.6 - 36.0%) | 37.3% (36.2 - 38.4%) | 37.8% (36.6 - 39.0%)
| Median LOS (death) | 5.6 (5.5 - 5.8) | 5.3 (5.2 - 5.4) | 5.3 (5.2 - 5.4)
| Median LOS (discharge) | 6.0 (5.8 - 6.1) | 5.9 (5.8 - 5.9) | 5.7 (5.6 - 5.8)
May-20 |  |  |
| HFR | 28.4% (27.1 - 29.8%) | 33.6% (31.5 - 35.7%) | 27.9% (23.4 - 33.3%)
| Median LOS (death) | 6.5 (6.4 - 6.7) | 6.6 (6.4 - 6.9) | 6.4 (6.0 - 7.0)
| Median LOS (discharge) | 5.3 (5.1 - 5.4) | 5.9 (5.7 - 6.1) | 6.2 (5.6 - 7.0)
Jun-20 |  |  |
| HFR | 20.3% (18.7 - 22.0%) | 28.4% (21.5 - 37.4%) | 11.9% (5.2 - 27.1%)
| Median LOS (death) | 7.8 (7.5 - 8.1) | 6.8 (6.4 - 7.7) | 15.0 (7.2 - 16.9)
| Median LOS (discharge) | 4.8 (4.6 - 4.9) | 6.3 (5.6 - 7.1) | 6.7 (5.4 - 7.9)
Jul-20 |  |  |
| HFR | 13.2% (11.3 - 15.5%) | - | -
| Median LOS (death) | 10.3 (9.6 - 10.9) | - | -
| Median LOS (discharge) | 4.0 (3.8 - 4.2) | - | -
Aug-20 |  |  |
| HFR | 12.4% (10.3 - 14.9%) | 14.4% (4.0 - 52.0%) | -
| Median LOS (death) | 9.9 (9.2 - 10.9) | 5.0 (2.5 - 6.4) | -
| Median LOS (discharge) | 3.1 (2.9 - 3.3) | 4.5 (2.0 - 5.5) | -
Sep-20 |  |  |
| HFR | 13.7% (12.5 - 15.1%) | 19.6% (17.4 - 22.2%) | 17.6% (11.0 - 28.3%)
| Median LOS (death) | 9.2 (8.9 - 9.6) | 8.9 (8.5 - 9.4) | 4.0 (2.2 - 4.9)
| Median LOS (discharge) | 3.9 (3.8 - 4.0) | 4.7 (4.5 - 4.9) | 2.8 (2.4 - 3.6)
Oct-20 |  |  |
| HFR | 15.9% (14.9 - 17.1%) | 19.3% (18.1 - 20.6%) | 20.6% (19.4 - 21.9%)
| Median LOS (death) | 9.1 (8.8 - 9.4) | 8.7 (8.4 - 9.0) | 8.4 (8.1 - 8.7)
| Median LOS (discharge) | 4.4 (4.3 - 4.4) | 4.3 (4.2 - 4.4) | 4.5 (4.4 - 4.6)
Nov-20 |  |  |
| HFR | 17.4% (16.4 - 18.6%) | 20.8% (19.7 - 21.9%) | 20.8% (19.8 - 21.8%)
| Median LOS (death) | 9.2 (8.9 - 9.5) | 8.7 (8.5 - 9.0) | 8.3 (8.1 - 8.5)
| Median LOS (discharge) | 4.9 (4.8 - 5.0) | 4.9 (4.8 - 5.0) | 4.7 (4.6 - 4.8)
Dec-20 |  |  |
| HFR | 19.6% (17.9 - 21.5%) | 22.7% (21.8 - 23.5%) | 23.7% (22.8 - 24.6%)
| Median LOS (death) | 9.5 (9.1 - 9.9) | 8.7 (8.6 - 8.9) | 8.4 (8.2 - 8.6)
| Median LOS (discharge) | 4.9 (4.7 - 5.0) | 5.0 (4.9 - 5.0) | 5.2 (5.1 - 5.3)
Jan-21 |  |  |
| HFR | - | 19.4% (17.2 - 21.8%) | 22.2% (21.3 - 23.1%)
| Median LOS (death) | - | 8.1 (7.6 - 8.6) | 8.1 (7.9 - 8.2)
| Median LOS (discharge) | - | 4.8 (4.7 - 5.0) | 4.6 (4.5 - 4.6)
Feb-21 |  |  |
| HFR | 14.1% (12.9 - 15.3%) | 17.5% (16.7 - 18.3%) | 20.0% (19.0 - 21.1%)
| Median LOS (death) | 7.9 (7.7 - 8.2) | 8.0 (7.9 - 8.2) | 7.3 (7.1 - 7.6)
| Median LOS (discharge) | 4.3 (4.2 - 4.4) | 4.5 (4.5 - 4.6) | 4.6 (4.5 - 4.7)
Mar-21 |  |  |
| HFR | 10.1% (9.2 - 11.0%) | 12.2% (10.5 - 14.2%) | 12.4% (5.5 - 28.3%)
| Median LOS (death) | 8.8 (8.5 - 9.2) | 8.3 (7.8 - 9.1) | 14.5 (15.9 - 18.1)
| Median LOS (discharge) | 3.6 (3.5 - 3.6) | 3.9 (3.7 - 4.0) | 7.0 (5.4 - 9.6)
Apr-21 |  |  |
| HFR | 8.9% (7.6 - 10.3%) | - | -
| Median LOS (death) | 8.6 (8.2 - 9.0) | - | -
| Median LOS (discharge) | 3.2 (3.1 - 3.3) | - | -
May-21 |  |  |
| HFR | 8.9% (7.4 - 10.7%) | 5.6% (2.4 - 13.0%) | -
| Median LOS (death) | 10.1 (9.6 - 10.8) | 11.3 (5.5 - 17.5) | -
| Median LOS (discharge) | 2.8 (2.6 - 2.9) | 3.3 (2.7 - 3.8) | -
Jun-21 |  |  |
| HFR | 8.0% (7.0 - 9.1%) | 9.0% (7.1 - 11.3%) | 4.7% (1.8 - 12.3%)
| Median LOS (death) | 10.6 (10.2 - 11.0) | 10.0 (9.5 - 10.7) | 8.0 (4.5 - 11.3)
| Median LOS (discharge) | 2.7 (2.7 - 2.8) | 2.5 (2.3 - 2.6) | 4.2 (3.2 - 4.9)
Jul-21 |  |  |
| HFR | 8.2% (7.5 - 8.9%) | 10.0% (9.2 - 10.9%) | 8.2% (7.1 - 9.4%)
| Median LOS (death) | 10.2 (9.9 - 10.5) | 10.1 (9.8 - 10.4) | 8.5 (7.9 - 9.1)
| Median LOS (discharge) | 3.0 (2.9 - 3.0) | 3.1 (3.1 - 3.2) | 3.0 (2.9 - 3.1)
Aug-21 |  |  |
| HFR | 9.8% (9.0 - 10.5%) | 11.3% (10.5 - 12.1%) | 11.8% (10.4 - 13.4%)
| Median LOS (death) | 9.9 (9.5 - 10.2) | 9.7 (9.4 - 9.9) | 8.9 (8.5 - 9.4)
| Median LOS (discharge) | 3.4 (3.4 - 3.5) | 3.2 (3.1 - 3.3) | 2.8 (2.7 - 2.9)
Sep-21 |  |  |
| HFR | 9.8% (9.0 - 10.6%) | 11.2% (10.3 - 12.1%) | 11.9% (10.1 - 14.1%)
| Median LOS (death) | 7.6 (7.4 - 7.9) | 7.5 (7.2 - 7.7) | 8.2 (7.9 - 8.5)
| Median LOS (discharge) | 3.5 (3.4 - 3.6) | 3.8 (3.7 - 3.8) | 3.2 (3.1 - 3.4)
Table 14: * Supplementary table 8 continued |  |  |  |
---|---|---|---|---
Month of hospital admission | (60,80] | (80,90] | (90,100]
Mar-20 |  |  |
| HFR | 41.9% (39.7 - 44.2%) | 41.9% (37.9 - 46.3%) | 44.9% (39.6 - 50.9%)
| Median LOS (death) | 5.5 (5.3 - 5.6) | 5.5 (5.2 - 5.9) | 4.2 (3.8 - 4.7)
| Median LOS (discharge) | 5.8 (5.6 - 6.0) | 6.5 (6.2 - 6.9) | 5.0 (4.6 - 5.4)
Apr-20 |  |  |
| HFR | 38.4% (37.0 - 39.8%) | 38.4% (35.7 - 41.4%) | 38.6% (35.7 - 41.7%)
| Median LOS (death) | 4.9 (4.8 - 5.0) | 4.7 (4.4 - 4.9) | 5.2 (4.9 - 5.4)
| Median LOS (discharge) | 5.7 (5.6 - 5.8) | 5.7 (5.5 - 5.9) | 6.9 (6.7 - 7.2)
May-20 |  |  |
| HFR | 16.2% (8.9 - 29.4%) | 9.1% (1.4 - 58.9%) | 4.3% (0.6 - 29.6%)
| Median LOS (death) | 8.3 (4.1 - 10.9) | 21.0 (21.0 - 21.0) | 2.0 (2.0 - 2.0)
| Median LOS (discharge) | 8.5 (7.6 - 11.0) | 10.0 (6.2 - 11.4) | 11.3 (7.2 - 12.6)
Jun-20 |  |  |
| HFR | 8.4% (2.8 - 24.8%) | - | -
| Median LOS (death) | 9.3 (6.1 - 11.8) | - | -
| Median LOS (discharge) | 6.3 (4.6 - 7.8) | - | -
Jul-20 |  |  |
| HFR | - | - | -
| Median LOS (death) | - | - | -
| Median LOS (discharge) | - | - | -
Aug-20 |  |  |
| HFR | - | - | -
| Median LOS (death) | - | - | -
| Median LOS (discharge) | - | - | -
Sep-20 |  |  |
| HFR | 11.1% (1.8 - 70.5%) | - | -
| Median LOS (death) | 6.0 (6.0 - 6.0) | - | -
| Median LOS (discharge) | 2.0 (0.0 - 2.6) | - | -
Oct-20 |  |  |
| HFR | 20.9% (19.2 - 22.8%) | 23.1% (19.9 - 26.9%) | 20.0% (15.5 - 25.9%)
| Median LOS (death) | 8.0 (7.7 - 8.4) | 6.8 (6.1 - 7.6) | 7.3 (5.6 - 8.7)
| Median LOS (discharge) | 4.8 (4.6 - 4.9) | 5.2 (5.0 - 5.5) | 5.9 (5.6 - 6.3)
Nov-20 |  |  |
| HFR | 22.8% (21.5 - 24.2%) | 23.6% (21.5 - 25.8%) | 23.6% (21.1 - 26.4%)
| Median LOS (death) | 7.9 (7.6 - 8.2) | 7.4 (7.0 - 7.9) | 8.0 (7.6 - 8.5)
| Median LOS (discharge) | 4.8 (4.7 - 4.9) | 5.1 (4.9 - 5.2) | 5.2 (5.0 - 5.4)
Dec-20 |  |  |
| HFR | 22.2% (21.2 - 23.3%) | 22.7% (21.2 - 24.3%) | 19.8% (17.9 - 21.8%)
| Median LOS (death) | 8.2 (8.0 - 8.4) | 8.0 (7.8 - 8.4) | 7.9 (7.5 - 8.3)
| Median LOS (discharge) | 5.3 (5.2 - 5.4) | 4.7 (4.6 - 4.8) | 4.7 (4.6 - 4.9)
Jan-21 |  |  |
| HFR | 22.1% (21.5 - 22.7%) | 23.2% (22.5 - 24.0%) | 23.8% (23.2 - 24.4%)
| Median LOS (death) | 7.5 (7.4 - 7.6) | 7.2 (7.1 - 7.4) | 7.5 (7.4 - 7.6)
| Median LOS (discharge) | 5.0 (4.9 - 5.0) | 5.0 (4.9 - 5.0) | 4.9 (4.9 - 5.0)
Feb-21 |  |  |
| HFR | 19.1% (16.9 - 21.7%) | 19.6% (10.1 - 38.0%) | 11.8% (3.2 - 43.2%)
| Median LOS (death) | 7.7 (7.3 - 8.1) | 12.0 (5.4 - 14.5) | 20.0 (7.7 - 26.8)
| Median LOS (discharge) | 5.8 (5.5 - 6.0) | 8.0 (7.5 - 8.8) | 17.0 (6.5 - 20.0)
Mar-21 |  |  |
| HFR | 4.8% (0.7 - 32.2%) | - | -
| Median LOS (death) | 2.0 (2.0 - 2.0) | - | -
| Median LOS (discharge) | 3.0 (1.5 - 4.7) | - | -
Apr-21 |  |  |
| HFR | - | - | -
| Median LOS (death) | - | - | -
| Median LOS (discharge) | - | - | -
May-21 |  |  |
| HFR | - | - | -
| Median LOS (death) | - | - | -
| Median LOS (discharge) | - | - | -
Jun-21 |  |  |
| HFR | - | - | -
| Median LOS (death) | - | - | -
| Median LOS (discharge) | - | - | -
Jul-21 |  |  |
| HFR | 5.9% (4.1 - 8.5%) | - | -
| Median LOS (death) | 10.4 (8.5 - 11.8) | - | -
| Median LOS (discharge) | 2.8 (2.6 - 3.0) | - | -
Aug-21 |  |  |
| HFR | 10.8% (6.8 - 17.1%) | 18.3% (9.8 - 34.2%) | 3.9% (0.6 - 26.4%)
| Median LOS (death) | 6.7 (4.4 - 8.3) | 4.0 (3.8 - 5.1) | 5.0 (5.0 - 5.0)
| Median LOS (discharge) | 3.2 (2.7 - 3.6) | 1.9 (1.6 - 2.2) | 1.2 (0.8 - 1.4)
Sep-21 |  |  |
| HFR | 11.7% (7.6 - 18.0%) | - | -
| Median LOS (death) | 7.0 (4.1 - 11.9) | - | -
| Median LOS (discharge) | 3.2 (2.6 - 3.9) | - | -

Table 15: * Supplementary table 9: Hospitalised fatality sub-distribution hazard ratio by month of hospital admission, stratified by age group, region of residence and vaccination status, with regression adjustment (main effects) on sex, ethnicity, IMD quintile, CCI and hospital load. Figures in brackets represent 95% confidence intervals. |
---|---
Month of hospital admission | Hazard ratio
Mar-20 | 2.30 (2.08, 2.55)
Apr-20 | 1.93 (1.75, 2.13)
May-20 | 1.33 (1.20, 1.48)
Jun-20 | 1 (reference category)
Jul-20 | 0.74 (0.61, 0.91)
Aug-20 | 0.87 (0.69, 1.08)
Sep-20 | 1.07 (0.94, 1.21)
Oct-20 | 1.11 (1.00, 1.23)
Nov-20 | 1.14 (1.03, 1.26)
Dec-20 | 1.30 (1.17, 1.44)
Jan-21 | 1.32 (1.19, 1.46)
Feb-21 | 1.19 (1.07, 1.32)
Mar-21 | 1.00 (0.88, 1.14)
Apr-21 | 0.90 (0.75, 1.10)
May-21 | 1.20 (0.97, 1.50)
Jun-21 | 1.43 (1.23, 1.68)
Jul-21 | 1.31 (1.16, 1.47)
Aug-21 | 1.31 (1.17, 1.48)
Sep-21 | 1.15 (1.02, 1.30)

Table 16: * Supplementary table 10: Hospitalised fatality sub-distribution hazard ratios by person characteristic, stratified by age group, PHE centre of residence and month of hospitalisation, with regression adjustment (main effects) on vaccination status, sex, ethnicity, IMD quintile, CCI and hospital load. January to September 2021. Figures in brackets represent 95% confidence intervals. |  |
---|---|---
Characteristic | Hazard ratio
Vaccination status |
| Unvaccinated | 1 (reference category)
| <21 days after first vaccination dose | 0.93 (0.89 - 0.98)
|  $\geq$21 days after first vaccination dose | 0.71 (0.67 - 0.77)
|  $\geq$14 days after second vaccination dose | 0.56 (0.52 - 0.61)
Sex |
| Male | 1.28 (1.24 - 1.32)
| Female | 1 (reference category)
Ethnicity |
| White | 1 (reference category)
| Asian | 1.19 (1.13 - 1.25)
| Black | 0.90 (0.84 - 0.97)
| Mixed/Other/Unknown | 1.02 (0.94 - 1.10)
Index of multiple deprivation |
| 1st quintile (most deprived) | 1.10 (1.05 - 1.15)
| 2nd quintile | 1.09 (1.04 - 1.14)
| 3rd quintile | 1.06 (1.01 - 1.11)
| 4th quintile | 1.03 (0.98 - 1.09)
| 5th quintile (least deprived) | 1 (reference category)
Charleson comorbidity index |
| 0 | 1 (reference category)
| 1-2 | 1.92 (1.83 - 2.01)
| 3-4 | 2.79 (2.65 - 2.94)
| 5+ | 3.46 (3.27 - 3.67)
Hospital load at time of admission (as proportion of busiest week)
| 0-20% | 1 (reference category)
| 20-40% | 1.11 (1.04 - 1.19)
| 40-60% | 1.18 (1.10 - 1.28)
| 60-80% | 1.15 (1.05 - 1.25)
| 80-95% | 1.22 (1.11 - 1.33)
| 95-100% | 1.23 (1.12 - 1.34)

## Supplementary references

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