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

Abstract

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.

Keywords: COVID-19 mortality; Cross-infection; Deaths; Healthcare-associated infection; Hospital-onset COVID-19; Nosocomial COVID-19; SARS-CoV-2.