Body mass index and critical care outcomes in hospitalized COVID-19 patients—A national cohort study

Abstract

Background The COVID-19 pandemic caused significant global mortality. Obesity is associated with worse COVID-19 outcomes. This study examined the relationship between BMI, clinical interventions, and outcomes in hospitalized COVID-19 patients using pre-vaccine national data. Methods We conducted a retrospective cohort study using de-identified electronic health records from the HCA Healthcare database, comprising 149 hospitals across 18 U.S. states. Adults (≥18 years) hospitalized with confirmed SARS-CoV-2 infection between March 1 and December 31, 2022, were included. The primary outcome was a composite of in-hospital mortality or discharge to hospice, analyzed by BMI category. Secondary outcomes included inpatient mortality, need for mechanical ventilation or tracheostomy, duration of mechanical ventilation, and ICU (Intensive Care Unit) length of stay. Results Out of 38,321 hospital encounters, 21,996 met the inclusion criteria. Unadjusted analyses showed no significant differences in rates of all-cause mortality or hospice discharge across BMI categories. However, obese patients had higher rates of mechanical ventilation (7.8% vs. 4.6%, p < 0.001), tracheostomy placement (1.2% vs. 0.6%, p < 0.001), longer duration of mechanical ventilation (mean 11.5 ± 15.1 vs. 6.8 ± 8.7 days, p < 0.001), and longer ICU stays (8.3 ± 10.4 vs. 5.1 ± 6.4 days, p < 0.001) than normal BMI patients. In adjusted analyses controlling for age, sex, race, ethnicity, and comorbidities, obesity was independently associated with increased odds of all-cause mortality or hospice discharge (OR 1.29, 95% CI: 1.08–1.55, p < 0.05), inpatient mortality (OR 1.67, 95% CI: 1.34–2.08, p < 0.001), need for invasive mechanical ventilation (OR 1.55, 95% CI: 1.31–1.82, p < 0.001), and tracheostomy placement (OR 1.57, 95% CI: 1.03–2.41, p < 0.05). Obesity was a significant predictor of longer duration of mechanical ventilation (β = 3.67 days, 95% CI: 1.28–6.06, p < 0.001) and ICU stay (β = 2.90 days, 95% CI: 2.08–3.72, p < 0.001). Conclusion Obesity was independently associated with increased risk of adverse clinical outcomes among hospitalized COVID-19 patients. These findings highlight the importance of BMI as a prognostic factor in acute COVID-19 management.