Mortality trends and length of stays among hospitalized patients with COVID-19 in Ontario and Québec (Canada): a population-based cohort study of the first three epidemic waves

Yiqing Xia; Huiting Ma; David L Buckeridge; Marc Brisson; Beate Sander; Adrienne Chan; Aman Verma; Iris Ganser; Nadine Kronfli; Sharmistha Mishra; Mathieu Maheu-Giroux

doi:10.1016/j.ijid.2022.04.048

Mortality trends and length of stays among hospitalized patients with COVID-19 in Ontario and Québec (Canada): a population-based cohort study of the first three epidemic waves

Int J Infect Dis. 2022 Aug:121:1-10. doi: 10.1016/j.ijid.2022.04.048. Epub 2022 Apr 25.

Authors

Affiliations

¹ Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, QC, Canada.
² MAP Centre for Urban Health Solutions, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada.
³ Département de médecine sociale et préventive, Faculté de médecine, Université Laval, Québec, QC, Canada.
⁴ Institute of Health Policy, Management and Evaluation (IHPME), Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Toronto Health Economics and Technology Assessment (THETA) collaborative, University Health Network, Toronto, ON, Canada; Public Health Ontario, Toronto, ON, Canada; ICES, Toronto, ON, Canada.
⁵ Institute of Health Policy, Management and Evaluation (IHPME), Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada.
⁶ Centre for Outcomes Research and Evaluation (CORE), Research Institute of the McGill University Health Centre, Montréal, QC, Canada; Department of Medicine, Division of Infectious Diseases and Chronic Viral Illness Service, McGill University Health Centre, Montréal, QC, Canada.
⁷ MAP Centre for Urban Health Solutions, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada; Institute of Health Policy, Management and Evaluation (IHPME), Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada; Division of Infectious Diseases, Department of Medicine, University of Toronto, Toronto, ON, Canada; Institute of Medical Sciences, University of Toronto, Toronto, ON, Canada.
⁸ Department of Epidemiology and Biostatistics, School of Population and Global Health, McGill University, Montréal, QC, Canada. Electronic address: mathieu.maheu-giroux@mcgill.ca.

Abstract

Background: Epidemics of COVID-19 strained hospital resources. We describe temporal trends in mortality risk and length of stays in hospital and intensive care units (ICUs) among patients with COVID-19 hospitalized through the first three epidemic waves in Canada.

Methods: We used population-based provincial hospitalization data from the epicenters of Canada's epidemics (Ontario and Québec). Adjusted estimates were obtained using marginal standardization of logistic regression models, accounting for patient-level and hospital-level determinants.

Results: Using all hospitalizations from Ontario (N = 26,538) and Québec (N = 23,857), we found that unadjusted in-hospital mortality risks peaked at 31% in the first wave and was lowest at the end of the third wave at 6-7%. This general trend remained after adjustments. The odds of in-hospital mortality in the highest patient load quintile were 1.2-fold (95% CI: 1.0-1.4; Ontario) and 1.6-fold (95% CI: 1.3-1.9; Québec) that of the lowest quintile. Mean hospital and ICU length of stays decreased over time but ICU stays were consistently higher in Ontario than Québec.

Conclusions: In-hospital mortality risks and length of ICU stays declined over time despite changing patient demographics. Continuous population-based monitoring of patient outcomes in an evolving epidemic is necessary for health system preparedness and response.

Keywords: COVID-19; hospitalization; length of stay in intensive care units; mortality risk.

MeSH terms

COVID-19*
Cohort Studies
Epidemics*
Hospital Mortality
Hospitalization
Humans
Intensive Care Units
Length of Stay
Ontario / epidemiology
Quebec / epidemiology
Retrospective Studies