Does body mass index influence mortality in patients with heart failure?

Introduction and objectives. Obesity is an independent risk factor for congestive heart failure. Paradoxically, improved survival has been observed in obese heart failure patients. The objective of this study was to analyze the relationship between body mass index (BMI) and the 2-year mortality rate in outpatients with heart failure of different etiologies who were attending a heart failure unit. Methods. Baseline BMI and survival status at 2-year follow-up were recorded in 501 patients (73% men, median age 68 years). Heart failure etiology was mainly ischemic heart disease, present in 59%. The patients' median ejection fraction was 30%. They were divided into four groups according to BMI: low weight (< 20.5), normal weight (20.5 to < 25.5), overweight (25.5 to < 30), and obese (>= 30). Results. The mortality rate at 2 years differed significantly (P <.001) between the groups: 46.7% for low-weight patients, 27.8% for normal-weight patients, 18.7% for overweight patients, and 16% for obese patients. After adjusting for age, sex, heart failure etiology, functional class, ejection fraction, hypertension, diabetes, estimated creatinine clearance rate, plasma hemoglobin level, and treatment received, BMI remained an independent predictor of reduced mortality at 2 years (odds ratio=0.92 [0.88-0.97]). Conclusions. A high BMI has been associated with lower all-cause mortality rates at 2-year follow-up. Our findings in a broad population of patients with heart failure of different etiologies further confirm the existence of a paradoxical relationship between obesity and heart failure outcome.