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Published on: June 10, 2025
Association between baseline BMI and in-hospital mortality in critically ill cardiac surgery patients: a
Gang-Gang Peng1, Pan Zhou1, Wei Liu1
1Department of Emergency Medicine, Shenzhen Second People's Hospital/the First Affiliated Hospital of Shenzhen University, Shenzhen, 518035, China.
Background:
BMI-mortality associations in critically ill cardiac surgery lack precise threshold characterization. We investigated the baseline BMI and in hospital mortality in ICU cardiac surgery patients.
Methods:
We included 8032 cardiac surgery patients from eICU (208 US hospitals, 2014-2015). Focus exposure: BMI; key outcome: 30-day mortality. Adjustments encompassed demographics, laboratory values, APACHE-IV scores, comorbidities, and interventions. Nonlinear patterns were examined via penalized spline-fitted generalized additive modeling.
Results:
Among 8,032 patients (BMI: 29.6 ± 6.8 kg/m2), in-hospital mortality occurred in 289 cases (3.6%). Standard linear modeling detected no BMI-mortality relationship (OR = 0.99, 95% CI 0.97-1.01, P = 0.210). Conversely, spline analysis identified a U-shaped pattern with inflection at 25.0 kg/m2. BMI increases below this point conferred 10% mortality reduction per unit (OR = 0.90, 95% CI 0.83-0.96, P = 0.003), while higher values showed null association (OR = 1.01, 95% CI 0.98-1.03, P = 0.567). Log-likelihood ratio testing favored the nonlinear approach (P = 0.010).
Conclusions:
Our analysis identified a U-shaped BMI-mortality relationship in critically ill cardiac surgery patients, revealing an optimal risk threshold at 25.0 kg/m2. These findings may provide valuable guidance for perioperative BMI management in this population.
