TY - JOUR T1 - Organ dysfunction and death in patients admitted to hospital with COVID-19 in pandemic waves 1 to 3 in British Columbia, Ontario and Quebec, Canada: a cohort study JF - CMAJ Open JO - CMAJ SP - E379 LP - E389 DO - 10.9778/cmajo.20210216 VL - 10 IS - 2 AU - Terry Lee AU - Matthew P. Cheng AU - Donald C. Vinh AU - Todd C. Lee AU - Karen C. Tran AU - Brent W. Winston AU - David Sweet AU - John H. Boyd AU - Keith R. Walley AU - Greg Haljan AU - Allison McGeer AU - François Lamontagne AU - Robert Fowler AU - David Maslove AU - Joel Singer AU - David M. Patrick AU - John C. Marshall AU - Kevin D. Burns AU - Srinivas Murthy AU - Puneet K. Mann AU - Geraldine Hernandez AU - Kathryn Donohoe AU - Genevieve Rocheleau AU - James A. Russell A2 - , Y1 - 2022/04/01 UR - http://www.cmajopen.ca/content/10/2/E379.abstract N2 - Background: There have been multiple waves in the COVID-19 pandemic in many countries. We sought to compare mortality and respiratory, cardiovascular and renal dysfunction between waves in 3 Canadian provinces.Methods: We conducted a substudy of the ARBs CORONA I study, a multicentre Canadian pragmatic observational cohort study that examined the association of pre-existing use of angiotensin receptor blockers with outcomes in adults admitted to hospital with acute COVID-19 up to April 2021 from 9 community and teaching hospitals in 3 Canadian provinces (British Columbia, Ontario and Quebec). We excluded emergency department admissions without hospital admission, readmissions and admissions for another reason. We used logistic and 0–1-inflated β regression models to compare 28-day and in-hospital mortality, and the use of invasive mechanical ventilation, vasopressors and renal replacement therapy (RRT) between the first 3 waves of the COVID-19 pandemic in these provinces.Results: A total of 520, 572 and 245 patients in waves 1, 2 and 3, respectively, were included. Patients in wave 3 were on average younger and had fewer comorbidities than those in waves 1 and 2. The unadjusted 28-day mortality rate was significantly lower in wave 3 (7.8%) than in wave 1 (18.3%) (odds ratio [OR] 0.43, 95% confidence interval [CI] 0.24–0.78) and wave 2 (16.3%) (OR 0.46, 95% CI 0.27–0.79). After adjustment for differences in baseline characteristics, the difference in 28-day mortality remained significant (adjusted OR wave 3 v. wave 1: 0.46, 95% CI 0.26–0.81; wave 3 v. wave 2: 0.52, 95% CI 0.29–0.91). In-hospital mortality findings were similar. Use of invasive mechanical ventilation or vasopressors was less common in waves 2 and 3 than in wave 1, and use of RRT was less common in wave 3 than in wave 1.Interpretation: Severity of illness decreased (lower mortality and less use of organ support) across waves among patients admitted to hospital with acute COVID-19, possibly owing to changes in patient demographic characteristics and management, such as increased use of dexamethasone. Continued application of proven therapies may further improve outcomes.Study registration: ClinicalTrials.gov, no. NCT04510623 ER -