Critical illness in patients with omicron variant COVID-19: different but crucial

ABSTRACT

Introduction: During the COVID-19 pandemic, various virus variants evolved worldwide. COVID-19 omicron (CO) was associated with a decrease in length of hospital stay, ICU admission and death [1] as compared to COVID-19 delta (CD). To estimate impact of CO on ICUs worldwide, we investigated characteristics, disease course and outcome of critically ill CO patients. Method(s) Of 8562 critically ill COVID-19 patients included in the prospective international multicenter RISC-19-ICU registry [2,3], characteristics and outcome were compared for 1890 CD and 272 CO patients admitted to ICU between 1-2021 and 9-2022. Mixed model analysis corrected for individual center effects and adjusted for age, sex, vaccination status, use of steroids and anticoagulants was used. Result(s) There was no difference in age, sex and BMI between groups. CO patients had more comorbidities [mean difference (MD) 0.7, 95% CI (0.5-1.0), p = 0.02], especially arterial hypertension, and higher SAPS II score [MD 0.0 (0-0.1), p < 0.001], SOFA score [MD 0.1 (0.1-0.3), p < 0.0001]. CO patients presented with higher cardiovascular system SOFA subscore, but better PF-ratio at ICU admission and smaller risk for intubation and mechanical ventilation throughout their ICU stay [OR 0.5 (0.3-0.8)]. There was no difference in ECMO treatments, ICU length of stay [MD 0.6 (0-11.4), p = 0.72] or ICU survival [HR 1 (0.7-1.5), p = 0.88] between the two groups. Conclusion(s) We show that critically ill CO patients present with more comorbidities, less severe respiratory disease but more severe hemodynamic instability at ICU admission as compared to CD patients, although the ICU length of stay and mortality was similar. These differences could be explained by differences in disease characteristics caused by CO, or by the increasing prevalence of CO as co-factor to preexisting disease. Continued monitoring of critically ill CO patients in ICUs worldwide is warranted.