Mortality amongst hospitalized COVID-19 cases by acquisition and pandemic wave in Wales, UK, February 2020-March 2022.

BACKGROUND

Hospital populations are vulnerable to COVID-19, but the relative severity of hospital acquisition compared to community is unknown. We investigated differences in mortality between hospital and community acquired cases in Wales.

METHODS

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) polymerase chain reaction tests from February 2020 to March 2022 were linked with hospital admissions to identify likely hospital-acquired cases. All-cause mortality within 28 days of a positive SARS-CoV-2 were measured by source of acquisition. Multi-variable logistic regression was used to compare mortality by source of acquisition, adjusting for confounders, computing adjusted odds ratios (aOR) with 95% confidence intervals (CI).

RESULTS

There were 25,263 hospital-acquired cases of COVID-19 and 5490 (22%) deaths in the study period. Although significant on univariate analysis, adjustment for confounding showed no association with increased mortality for hospital-acquired cases compared with cases admitted with COVID-19 (aOR 0.8, 95% CI 0.7-0.8). Vaccination (aOR 0.6, 95% CI 0.5-0.7) and infection in later pandemic waves (aOR 0.5, 95% CI 0.4-0.6) were associated with lower mortality; older age (≥85 vs <25 years: aOR 76.4, 95% CI 41.8-160.5) and male sex (aOR 1.5, 95% CI 1.4-1.6) were associated with higher mortality.

CONCLUSION

One in five hospitalised COVID-19 cases died within a month of infection. Mortality in nosocomial cases was not worse than those admitted with COVID-19, possibly reflecting early identification of nosocomial cases through screening.