Hospitalization trends and associated factors for COVID in 2.3 million adults in England

The case-fatality ratio and the case hospitalization ratio (CHR) for coronavirus disease 2019(COVID-19), can vary over time. Notably, the effect of the underlying risk of those who are infected on these ratios is still unknown.

Several studies have been conducted to characterize the risk factors associated with hospitalization and mortality in COVID-19 patients. However they might not be representative of future pandemic waves, along with the development of new variants.

Study: Trends in Covid-19 hospitalisations and fatality risks in 2.3 million adults in England. Image source: Blue Planet Studio/

Information about the study

In a recent article published on the pre-print server medRxiv* researchers from the United Kingdom performed a national level, retrospective cohort study with the primary goal of determining the risks for mortality and hospitalization over time among COVID-19 patients in England.

The secondary aim of this study was to identify patient characteristics associated with mortality risk and hospitalization. Researchers were also interested in determining whether residual unexplained variation in the CHR and CFR persists after accounting for the differences in the risk factors of patients infected.

Aged 18 or over who were positive for COVID-19 between the 1st of October, 2020, and April 30, 2021, were enrolled in the study. The information of participants was linked to primary as well as secondary care electronic records as well as death registers.

The participants were monitored from the day of positive coronavirus infection with severe acute respiratory syndrome 2 (SARS-CoV-2) test for up to 28 days. The main outcomes of this study was one or more deaths or emergency hospitalizations within 28 days.

To assess the outcome for each for each outcome, a multivariable multilevel regression model was employed. This model included risk factors for patients as well as time. In addition the CHRs for age and time and CFR were calculated for each outcome by calculating each outcome’s predicted probability within the age group.


There were 2,311,282 people who were included in the current study, of which 164,046 were admitted to hospitals at least once during the entire study duration. This means that the CHR was 7.1 5 percent and 53,156 deaths occurred within 28 days after a positive test, which suggests the CFR was 2.3%.

From late December 2020 until the beginning of February 2021, a significant increase in hospitalization rates as well as mortality risk was observed. This was the case even after individual risk factor adjustment. CHR reached its highest point in January 2021 for people aged 40 and over. It has remained constant since it was first observed, and is likely to rise until April 2021.

The study found an increased risk of hospitalization and mortality among males, older people who are of Asian and Black ethnic backgrounds, and those living in more deprived areas. The study also found that people who are overweight were at a higher risk of having a 10% likelihood of being hospitalized and a 99% higher likelihood of dying. This could be due to unmeasured conditions like fragility. People who were overweight had a 93% higher chance of being hospitalized, but a 4% increase in mortality risk when opposed to those with a healthy weight.

The U.K. established a clinically extremely vulnerable status (CEV) for those who are at the highest risk of dying from COVID-19 due to various risk factors, such as overweight, aging, male gender, or weight. The results of the study indicated an increase of 85% in the risk of hospitalization but a 12% lower risk of death in CEV patients after adjusting 100% of risk factors specific to each individual. Current smokers displayed an lower risk of hospitalization in comparison to non-smokers however there was an increase in the risk of death after adjustment.

The study also showed a strong correlation between chronic conditions like chronic respiratory disease, hypertension and chronic kidney disease, learning disability, diabetes stroke, hospitalizations, and deaths. However, this was not the case for those suffering from dementia who had a 6% lower risk of being hospitalized.


The study results showed that death and hospitalization rates from COVID-19 were significantly higher in the second wave of the COVID-19 pandemic. This was independent of the severity of the infection. Individual risk factors, such as older adults males, those living in poor areas, as well as those suffering from overweight, were associated with higher mortality and hospitalization rates. The study found that mental illness were associated with the most high risk of hospitalization as well as mortality, thus emphasizing the need for better medical attention and research in these groups.

*Important notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

Content Source:

Gemma Wilson

Gemma is a journalism graduate with keen interest in covering business news – specifically startups. She has as a keen eye for technologies and has predicted quite a few successful startups over the last couple of years.

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