Descriptive Comparison Between Pre-COVID ARDS and COVID-19 Related ARDS

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RATIONALE: Preliminary studies have shown varied outcomes when comparing Acute Respiratory Distress Syndrome (ARDS) caused by Coronavirus Disease 2019 (COVID-19) versus “Classic” ARDS. The aim of this study was to compare patient characteristics and outcome of ARDS before and during COVID-19 pandemic. METHODS: We conducted a single center retrospective cohort study at 3 hospitals sites of Montefiore Medical Center comparing a pre-COVID respiratory failure cohort from 2017 to 2018 and a COVID respiratory failure cohort from March 2020 to May 2020. ARDS was identified by having PaO2/FiO2 ratio <= 300 and independent x-ray review consistent of bilateral infiltrates according to 2012 Berlin definition. We used Mann-Whitney-U test for non-parametric comparison of continuous variables and chi-square test for categorical variables. P < 0.05 is considered statistically significant. RESULTS: We included 1328 ARDS pre-COVID patients from 2017-2018 and 536 COVID-19 patients. The age or race was not different between the 2 ARDS cohorts (Table 1). There were more males in the COVID-19 ARDS (56.2% pre-COVID vs 61.4% COVID-19;p = 0.039). The median PaO2/FiO2 ratio for pre-COVID ARDS was higher than COVID (184 (IQR 117, 242) vs 116 (IQR 80.3, 178), p < 0.0005) with less severe ARDS in pre-COVID (18.3% vs 38.2%;p < 0.0005). In-hospital mortality almost doubled in COVID-19 ARDS (68.8%) compare with pre-COVID ARDS (37.2%, p <0.0005). The hospital length of stay was significantly longer in pre-COVID ARDS;ICU length of stay and duration of mechanical ventilation did not differ between the two ARDS groups (Table 1). CONCLUSIONS: COVID-19 ARDS presented more severely than pre-COVID ARDS based on PaO2/FiO2 ratio. The increase in in-hospital mortality in COVID-19 ARDS is likely related to the severity of respiratory failure. We need to adjust for the confounders between ARDS types and patient outcomes.