Obesity paradox in coronary artery disease: national inpatient sample analysis

Although existing literature highlights obesity as a significant predictor for coronary artery disease (CAD), the impact of BMI on hospital outcomes among CAD patients remains unclear.

We extracted data from the National Inpatient Sample database for adult patients with CAD from 2018 to 2020. The study cohort was stratified into six BMI categories: underweight, normal weight, overweight, class I obesity, class II obesity, and class III obesity. Using multivariable logistic and linear regression, we assessed the impact of BMI on in-hospital mortality, length of stay (LOS), and inflation-adjusted total charges.

We identified a total of 3 693 570 hospitalizations (mean age: 69 ± 12 years). Underweight individuals had the highest in-hospital mortality rate (6.8%), followed by normal weight (5.2%), overweight (3.2%), class III obese (2.5%), class I obese (1.9%), and class II obese (1.8%) individuals. After adjusting for covariates, underweight patients had higher odds of in-hospital mortality compared to normal-weight individuals [odds ratio (OR), 1.38; 95% confidence interval (CI), 1.31-1.45; P < 0.001], while overweight or obese individuals had lower odds: overweight (OR, 0.75; 95% CI, 0.70-0.79; P < 0.001), obese class I: (OR, 0.54; 95% CI, 0.51-0.57; P < 0.001), obese class II: (OR, 0.56; 95% CI, 0.53-0.59; P < 0.001), obese class III: (OR, 0.78; 95% CI, 0.74-0.82; P < 0.001). Normal weight and underweight patients had the longest median LOS [5 days (3.0-9.0)]. Overweight patients incurred the highest total charges [$53 730 (28 587-105 184)].

Underweight patients experienced higher, while overweight and obese patients experienced lower in-hospital mortality than normal-weight patients, suggesting a protective effect of higher BMI against mortality in CAD.