Factors Associated with Mortality in Patients with COVID-19 Requiring Mechanical Ventilation: An International Cohort Study from 139 Intensive Care Unit Across 6 Continents

Abstract

Rationale: Patients with COVID-19 commonly develop severe hypoxemic respiratory failure and require invasive mechanical ventilation (MV). The disease burden and predictors of mortality in this population remain uncertain. Methods: Prospective observational cohort study from 139 intensive care units of the international COVID-19 Critical Care Consortium. Patients enrolled from January 14th through November 31st 2020 were included in the analysis. Patient's characteristics and clinical data were assessed. Multivariable Cox proportional hazards analysis was conducted to identify indipendent predictors of mortality within 28 days from commencement of MV. Results: 1578 patients on MV were included into the analysis. Mean±SD age was 59 years±13 and patients were predominantly males (66%). 542 Patients (34.4%) died within 28 days from commencement of MV. Nonsurvivors were slightly older (mean age±SD 62±13 vs. 59±13) and presented more frequently hypertension, chronic cardiac disease and diabetes. Median (IQR) PaO2/FiO2 upon commencement of MV was 96 (68-135) and 111 (81-173) in patients who did not survive vs. survivors, respectively (p=0.04). ECMO (13% vs 25%, p<0.01), inhaled nitric oxide (11% vs 15%, p=0.02) and recruitment manoeauvres (26% vs 31%, p<0.01) were used less frequently in patients who did not survive. Independent risk factors associated with 28-day mortality included age older than 70 years (hazard ratio [HR], 2.83;95% CI, 1.32-6.07), higher creatinine levels upon ICU admission (HR, 1.20;95% CI, 1.03-1.40), and lower pH within 24h from commencement of MV (HR, 0.12;95% CI, 0.02-0.62), while a shorter period (day) from early symptoms to hospitalisation reduced mortality risks (HR, 0.96;95% CI, 0.93-0.99). Conclusions: Our findings from a large international cohort of critically-ill COVID-19 patients on mechanical ventilation emphasises that elderly patients, not promptly admitted to the hospital, and who present higher creatinine levels and acidosis are at higher risk of mortality.