Predictors of Mortality in COVID 19 Associated Respiratory Failure Among Predominantly African American Patients

Abstract

Rationale:Patients with COVID-19 frequently develop severe respiratory disease and may require invasive mechanical ventilation. A study of primarily white patients intubated for COVID-19 associated respiratory failure found predictors of 28-day mortality to be respiratory system compliance, age, tidal volume, arterial pH and heart rate. Little is known about the outcomes of minority populations with severe COVID-19 pneumonia. Therefore, we present an analysis of the predictors of mortality in a group of primarily African American patients with COVID-19 associated respiratory failure. Methods:All adult patients admitted to the University of Chicago COVID-19 intensive care unit receiving invasive mechanical ventilation between March 1st and June 31st, 2020 were identified. Patients were included in the study if they had at least one recorded measure of plateau airway pressure while receiving volume-controlled ventilation allowing determination of driving pressure and lung compliance. Univariable analysis was conducted comparing survivors with those who died in-hospital followed by construction of a multivariable logistic regression model predicting in-hospital mortality based on significant factors from univariable analysis, excluding colinear variables. Results:Eighty-five patients were included in this retrospective study. Patients were primarily African American (n=73, 86%). Among all study patients, median tidal volume was 6.0 cc/kg ideal body weight (IQR 5.8-6.2), PEEP was 8 cm H2O (IQR 5.0-10), and driving pressure was 14 cm H2O (IQR 11-16). Median respiratory system compliance was 27 ml/cm H2O (IQR 21-34). Salvage therapies for refractory hypoxemia in the cohort included prone positioning (27%), paralysis (27%), inhaled pulmonary vasodilators (19%), and extracorporeal membrane oxygenation (1%). In the multivariable logistic regression model, age (OR 1.077, 95% CI 1.031 to 1.125, p=0.001) and driving pressure (OR 1.174, 95% CI 1.009 to 1.366, p=0.038) were found to be independent predictors of mortality. Conclusions:In a predominantly African American patient population with COVID-19 pneumonia requiring invasive mechanical ventilation, higher driving pressure was predictive of overall mortality. These finding are consistent with the work of Botta et al (2020), who demonstrated reduced lung compliance was predictive of mortality among a largely white group of patients with severe COVID-19 pneumonia. While minority populations infected with COVID-19 have been found worse outcomes, early lung mechanics appear to be comparable to white patients. These findings support that higher driving pressures and low lung compliance are indicative of serious lung injury which may lead to death.