Impact of Body Mass Index on Mortality in Hospitalized Patients With Hypertrophic Cardiomyopathy

Although obesity is associated with increased phenotypic expression in patients with hypertrophic cardiomyopathy (HC), the effect of body mass index (BMI) on in-hospital mortality in hospitalized patients with HC has not been established. We evaluated the National Inpatient Sample in the United States to identify all adults with HC hospitalized for cardiac illnesses between 2008 and 2017. Using International Classification of Diseases codes, the study cohort was stratified into underweight (BMI ≤19.9 kg/m²), normal weight (BMI 20.0 to 24.9 kg/m²), overweight (BMI 25.0 to 29.9 kg/m²), class I (BMI 30.0 to 34.9 kg/m²), class II (BMI 35.0 to 39.9 kg/m²), and class III (BMI ≥40.0 kg/m²) obesity. Multiple logistic regression analysis was used to analyze the independent association of various BMI categories and mortality. The study included a total of 2,392,325 hospitalizations (mean age-66.1 ± 12.2 years; 42.0% female). The patients with class III obesity (adjusted mortality rate [AMR] 3.3%, adjusted odds ratio [AOR] 1.53, 95% confidence interval [CI] 1.29 to 1.82, p <0.001) and underweight patients (AMR 4.4%, AOR 2.07, 95% CI 1.74-2.46, p <0.001) had higher in-hospital mortality whereas overweight patients (AMR 1.6%, AOR 0.26, 95% CI 0.19 to 0.34, p <0.001), patients with class I obesity (AMR 0.8%, AOR 0.35, 95% CI 0.27 to 0.45, p <0.001) and patients with class II obesity (AMR 0.8%, AOR 0.34, 95% CI 0.26 to 0.45, p <0.001) had lower mortality compared with patients with normal BMI (AMR 2.9%). In conclusion, BMI has a nonlinear U-shaped relation with in-hospital mortality in patients with HC. The patients who were underweight and morbidly obese had significantly higher mortality, whereas those patients with overweight, class I, and class II obesity had lower mortality than normal BMI.