Clinical outcomes and lung mechanics characteristics between COVID-19 and non-COVID-19-associated acute respiratory distress syndrome: a propensity score analysis of two major randomized trials

OBJECTIVE: To compare the lung mechanics and outcomes between COVID-19-associated acute respiratory distress syndrome and non-COVID-19-associated acute respiratory distress syndrome. METHODS: We combined data from two randomized trials in acute respiratory distress syndrome, one including only COVID-19 patients and the other including only patients without COVID-19, to determine whether COVID-19-associated acute respiratory distress syndrome is associated with higher 28-day mortality than non-COVID-19 acute respiratory distress syndrome and to examine the differences in lung mechanics between these two types of acute respiratory distress syndrome. RESULTS: A total of 299 patients with COVID-19-associated acute respiratory distress syndrome and 1,010 patients with non-COVID-19-associated acute respiratory distress syndrome were included in the main analysis. The results showed that non-COVID-19 patients used higher positive end-expiratory pressure (12.5cmH2O; SD 3.2 versus 11.7cmH2O SD 2.8; p < 0.001), were ventilated with lower tidal volumes (5.8mL/kg; SD 1.0 versus 6.5mL/kg; SD 1.2; p < 0.001) and had lower static respiratory compliance adjusted for ideal body weight (0.5mL/cmH2O/kg; SD 0.3 versus 0.6mL/cmH2O/kg; SD 0.3; p = 0.01). There was no difference between groups in 28-day mortality (52.3% versus 58.9%; p = 0.52) or mechanical ventilation duration in the first 28 days among survivors (13 [IQR 5 - 22] versus 12 [IQR 6 - 26], p = 0.46). CONCLUSION: This analysis showed that patients with non-COVID-19-associated acute respiratory distress syndrome have different lung mechanics but similar outcomes to COVID-19-associated acute respiratory distress syndrome patients. After propensity score matching, there was no difference in lung mechanics or outcomes between groups.