Obesity paradox in coronary artery disease: national inpatient sample analysis

BACKGROUND: 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. METHODS: 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. RESULTS: 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)]. CONCLUSION: 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.