Factors Associated with Mortality in COVID-19 Patients Receiving Prolonged Ventilatory Support

Author(s):

Zachary Bergman; Jeffrey Chipman; Christopher Tignanelli; Gregory Beilman

Background:

Since its emergence in early 2020, COVID-19 associated pneumonia has caused a global strain on ICU resources with high rates of patients requiring intubation. These patients frequently require prolonged respiratory support and critical care. Multiple studies have demonstrated in-hospital mortality rates between 40-45% for COVID-19 patients that receive mechanical ventilation. However, outcomes for patients with prolonged intubation (>21 days) for COVID-19 have not been well established, nor have possible predictors of mortality in this patient group.

Hypothesis:

Age and comorbidities are predictors of mortality in patients ventilated for COVID-19 pneumonia. These variables will remain predictors in patients on mechanical ventilation for greater than 21 days.

Methods:

This is a retrospective evaluation of prospectively collected data from March 2020 through November 2021. Data collected included demographics, laboratory values, and outcomes of interest. Included were all patients admitted to a system of 11 hospitals with a confirmed COVID-19 infection and placed on mechanical ventilation during the study period. The primary endpoint was in-hospital mortality. Survival was assessed utilizing Kaplan-Meier survival curves and variables were compared using log-rank analysis and multivariate logistic regression.

Results:

There were 629 patients placed on mechanical ventilation for COVID-19 pneumonia during the study period, with in-hospital mortality of 40.1%.  Mortality was significantly associated with increased age and comorbidities including COPD, CAD, renal failure, and cancer history. Interestingly, for patients intubated for longer than 21 days (n=149), in-hospital mortality was dropped to 26.2%. In this group, increased age is associated with significantly worse survival, but studied comorbidities are no longer associated with increased mortality.

Conclusions:

In-hospital mortality in patients with COVID-19 pneumonia occurs primarily in the first 21 days after intubation, possibly related the greater risk of death from the active inflammatory process early in COVID-19 infection. Additional evaluation of one-year survival is necessary to establish the ongoing benefit of long-term mechanical ventilation for COVID-19.