Characteristics and outcomes of ICU-admitted COVID-19 patients in the Omicron and Alpha-dominated periods

Background: Comparing the outcomes of intensive care unit (ICU) admitted COVID-19 patients during the Alpha and Omicron-dominated periods. Methods: Patients with critical COVID-19 disease, requiring ICU admission from May to September 2021 and February to August 2022, were enrolled from a single medical center in Northern Taiwan. Clinical demographics, comorbidities, disease severity, and management strategies were recorded. The 28-day mortality from the two periods were compared both in the original and propensity score (PS)-matched cohort. Results: Of 231 patients, 72 (31.2%) were from the Alpha period and 159 (68.8%) from the Omicron period. Patients in the Omicron period were older, had a lower body mass index, more comorbidities, higher disease severities, and increased 28-day mortality (26.4% vs. 13.9%, p = 0.035). In multivariable analysis, the Omicron-dominated period was not identified as an independent factor associated with increased 28-day mortality. COVID-19 patients in Alpha- and Omicron-dominated periods had comparable 28-day mortality in PS-matched cohort (12.1% vs. 18.2%, p = 0.733). Independent factors associated with 28-day mortality were a lower PF ratio (PF ratio <100, adjusted odds ratio [aOR] 2.68, 95% confidence interval, CI 1.21–5.94), septic shock ([aOR] 2.39, 95% CI 1.12–5.09) and absence of remdesivir ([aOR] 0.36, 95% CI 0.16–0.83). Conclusion: While patients in the Omicron period exhibited greater severity, the variant was not independently linked to higher 28-day mortality in ICU-admitted patients.