COVID-19, other pneumonia causes associated with similar mortality after ventilation

Mechanically ventilated patients with pneumonia due to COVID-19 and pneumonia due to other causes have similar mortality rates but longer time to liberation from mechanical ventilation, a recent study found.

Data from early in the COVID-19 pandemic suggested that mortality rates might be higher for patients with COVID-19 pneumonia versus other types of pneumonia and that COVID-19 patients could benefit from less strict adherence to low tidal volume ventilation. To evaluate this further, researchers at Johns Hopkins Healthcare System performed a retrospective cohort study comparing patients with pneumonia due to COVID-19 (March 2020 to June 2021) or other causes (July 2016 to December 2019) who required mechanical ventilation in the first two weeks of hospitalization in community or academic hospitals. They analyzed clinical, laboratory, and mechanical ventilation data from admission to discharge or death. The primary outcome was 90-day in-hospital mortality, and secondary outcomes were time to liberation from mechanical ventilation, length of stay, static respiratory system compliance, and ventilatory ratio. The researchers compared clinical outcomes using unadjusted and multivariable-adjusted logistic regression, proportional hazards regression, and doubly robust regression in propensity score-matched sets. The results were published Jan. 10 by JAMA Network Open.

A total of 719 patients with severe COVID-19 pneumonia and 1,127 patients with severe non-COVID-19 pneumonia were included in the study. Mean age in each group was 61.8 and 60.9 years, respectively; 61.5% and 52.0% were men, 64.0% and 40.7% were in a racial minority group, and 35.2% and 58.1% were White. Unadjusted analyses found higher 90-day mortality (odds ratio, 1.21; 95% CI, 1.04 to 1.41), longer time on mechanical ventilation (subdistribution hazard ratio, 0.72; 95% CI, 0.63 to 0.81), and lower static respiratory compliance (32.0 vs. 28.4 mL/kg PBW/cm H₂O; P<0.001) in patients with COVID-19 versus non-COVID-19 pneumonia. In propensity score-matched analyses, patients with COVID-19 pneumonia were as likely to die within 90 days as patients with non-COVID-19 pneumonia (odds ratio, 1.04 [95% CI, 0.81 to 1.35]; P=0.85) and had similar respiratory system compliance (mean difference, 1.82 mL/cm H₂O [95% CI, −1.53 to 5.17 mL/cm H₂O]; P=0.28) and ventilatory ratio (mean difference, −0.05 [95% CI, −0.22 to 0.11]; P=0.52). However, rates of liberation from mechanical ventilation were lower in those with COVID-19 pneumonia (subdistribution hazard ratio, 0.81; 95% CI, 0.65 to 1.00), as were rates of being discharged alive at 90 days (subdistribution hazard ratio, 0.83; 95% CI, 0.68 to 1.01), although the latter finding was not statistically significant.

The study involved a single health system and did not include data on differences in patient management, among other limitations, the authors noted. They concluded that in this study, mechanically ventilated patients with severe COVID-19 pneumonia had similar mortality rates as patients with other causes of severe pneumonia but remained on mechanical ventilation longer. They said their findings and others indicate that use of mechanical ventilation in COVID-19 pneumonia should follow the same evidence-based guidelines as in any pneumonia. “We did not find convincing evidence of different physiologic phenotypes in patients with COVID-19 pneumonia,” the authors wrote. “We caution that deviating from current evidence-based practices (until there are robust data indicating why, how, and when) risks harm.”