Mortality in hospitalized older adults with COVID‐19 during three waves: A multicenter retrospective cohort study

BACKGROUND: The waves of COVID‐19 infections in Ontario, Canada, were marked by differences in patient characteristics and treatment. Our objectives were to (i) describe patient characteristics, treatment, and outcomes of hospitalized older adults with COVID‐19 between waves 1, 2, and 3, (ii) determine if there was an improvement in in‐hospital mortality in waves 2 and 3 after adjusting for covariates. METHODS: This retrospective cohort study was done in five acute care hospitals in Toronto, Ontario. Consecutive hospitalized older adults aged ≥65 years with confirmed COVID‐19 infection were included. Wave 1 extended from March 11 to July 31, 2020, wave 2 from August 1, 2020 to February 20, 2021, and wave 3 from February 21 to June 30, 2021. Patient characteristics and outcomes were abstracted from charts. A logistic regression model was used to determine the association between COVID‐19 and in‐hospital mortality in waves 2 and 3 compared with wave 1. RESULTS: Of the 1671 patients admitted to acute care, 297 (17.8%) were admitted in wave 1, 751 (44.9%) in wave 2, and 623 (37.3%) in wave 3. The median age of our cohort was 77.0 years (interquartile range: 71.0–85.0) and 775 (46.4%) were female. The prevalence of frailty declined in progressive waves. The use of dexamethasone, remdesivir, and tocilizumab was significantly higher in waves 2 and 3 compared with wave 1. In the unadjusted analysis, in‐hospital mortality was unchanged between waves 1 and 2, but it was lower in wave 3 (18.3% vs. 27.4% in wave 1). After adjustment, in‐hospital mortality was unchanged in waves 2 and 3 compared with wave 1. CONCLUSION: In‐hospital mortality in hospitalized older adults with COVID‐19 was similar between waves 1 and 3. Further research should be done to determine if COVID‐19 therapies have similar benefits for older adults compared with younger adults.