Association of obesity on short- and long-term survival in patients with moderate to severe pneumonia-related ARDS: a retrospective cohort study.

Summary

In 603 patients with microbiologically confirmed pneumonia-related ARDS, obesity (37.6%) was independently associated with lower 28-day mortality (aOR 0.55, 95% CI 0.33–0.90) but not with 90-day or 1-year mortality. Propensity matching confirmed lower 28-day mortality (15.2% vs 22%), and BMI as a continuous variable tracked with improved 28-day survival.

Key Findings

• Among 603 pneumonia-related ARDS patients, 37.6% were obese and obesity associated with female sex, hypertension, diabetes, COVID-19 pneumonia, and PaO2/FiO2 ≤ 100 mmHg.
• Obesity independently associated with lower 28-day mortality (aOR 0.55, 95% CI 0.33–0.90, p=0.02) but not 90-day or 1-year mortality.
• Propensity score matching showed lower 28-day mortality in obese vs non-obese patients (15.2% vs 22%, p=0.04).
• BMI as a continuous variable correlated with lower 28-day mortality (p=0.038), not at 90 days or 1 year.

Clinical Implications

Obesity should not be viewed as uniformly adverse in early ARDS mortality risk; prognostic models may incorporate BMI while avoiding therapeutic de-escalation, as no long-term survival benefit was observed.

Limitations

• Retrospective analysis with potential residual confounding and treatment heterogeneity.
• BMI measured in critical illness may be influenced by fluid status and does not reflect body composition.

Future Directions

External validation across centers, body composition-based phenotyping, and mechanistic studies to explain short-term benefit without long-term advantage.