Intensive care unit and hospital mortality for non-COVID critically ill patients before, and during the COVID-19 pandemic in Alberta hospitals: retrospective, observational cohort study

Objectives: The Coronavirus Disease-2019 (COVID-19) pandemic had indirect impacts on healthcare provided to critically ill intensive care unit (ICU) non-COVID patients and their outcomes. Therefore, we examined the effect of the COVID-19 pandemic on patients with non-COVID critical illness during the pandemic and pre-pandemic epochs. Design: Retrospective, population-based, observational cohort study. Setting: All adult patients admitted to general ICUs in Alberta, Canada, from March 2017-2020 (pre-pandemic period) and March 2020-2023 (pandemic period). Data sources: Data was captured from an integrated critical care clinical information system (eCritical Alberta) and Alberta Health Services (AHS) administrative databases were utilized. Measurements and main results: A total of 80,540 non-COVID patients were admitted to ICUs in Alberta in the period between March 2017 and March 2023, equally distributed between the pandemic (40,196, 50.1%) and pre-pandemic (40,344, 49.9%) periods. For pandemic versus pre-pandemic cohorts, patient mean age was 57.7 (16.2) vs 58.5 (16.6) years and mean APACHE II score was 19.5 (8.8) vs 18.8 (8.5), respectively. ICU mortality was higher during the pandemic compared with pre-pandemic (14.2% vs. 11.2%, mean difference [MD]: +3.1%, adjusted odds ratio [OR]: 1.12; 95% CI: 1.05-1.20, p<0.001) after logistic regression adjustment. The hospital mortality was significantly higher in the pandemic vs. the pre-pandemic period (23.6% vs. 15.9%; MD: +7.7%, adjusted OR: 1.91, 95% CI: 1.81-2.02, p<0.001). There was greater ICU (5.95 [9.4] vs. 5.35 [8.5] days, MD: +0.63 days, 95% CI: 0.47 to 0.72 days, p<0.001), and lower hospital (18.0 [28.0] vs. 19.9 [33.3] days, MD: -1.89 days, 95% CI: -1.45 to -2.32 days p<0.001) lengths of stay (LOS) during the pandemic compared with pre-pandemic. Conclusion: During the pandemic period, non-COVID patients had worse outcomes, greater adjusted ICU and hospital mortality, and higher resource utilization with increased ICU lengths of stay, when compared with pre-pandemic periods.