Mechanically ventilated COVID-19 patients admitted to the intensive care unit in the United States with or without respiratory failure secondary to COVID-19 pneumonia: a retrospective comparison of characteristics and outcomes

Background: There is increasing heterogeneity in the clinical phenotype of patients admitted to the intensive care unit (ICU) with coronavirus disease 2019 (COVID-19,) and reasons for mechanical ventilation are not limited to COVID pneumonia. We aimed to compare the characteristics and outcomes of intubated patients admitted to the ICU with the primary diagnosis of acute hypoxemic respiratory failure (AHRF) from COVID-19 pneumonia to those patients admitted for an alternative diagnosis. Methods: Retrospective cohort study of adults with confirmed SARS-CoV-2 infection admitted to nine ICUs between March 18, 2020, and April 30, 2021, at an urban university institution. We compared characteristics between the two groups using appropriate statistics. We performed logistic regression to identify risk factors for death in the mechanically ventilated COVID-19 population. Results: After exclusions, the final sample consisted of 319 patients with respiratory failure secondary to COVID pneumonia and 150 patients intubated for alternative diagnoses. The former group had higher ICU and hospital mortality rates (57.7% vs. 36.7%, P<0.001 and 58.9% vs. 39.3%, P<0.001, respectively). Patients with AHRF secondary to COVID-19 pneumonia also had longer ICU and hospital lengths-of-stay (12 vs. 6 days, P<0.001 and 20 vs. 13.5 days, P=0.001). After risk-adjustment, these patients had 2.25 times higher odds of death (95% confidence interval, 1.42-3.56; P=0.001). Conclusions: Mechanically ventilated COVID-19 patients admitted to the ICU with COVID-19-associated respiratory failure are at higher risk of hospital death and have worse ICU utilization outcomes than those whose reason for admission is unrelated to COVID pneumonia.