Pre-morbid body mass index and mortality after incident heart failure: the ARIC Study

Although obesity is an independent risk factor for heart failure (HF), once HF is established, obesity is associated with lower mortality. It is unclear if the weight loss due to advanced HF leads to this paradoxical finding.

This study sought to evaluate the prognostic impact of pre-morbid obesity in patients with HF.

In the ARIC (Atherosclerosis Risk In Communities) study, we used body mass index (BMI) measured ≥6 months before incident HF (pre-morbid BMI) to evaluate the association of overweight (BMI 25 to <30 kg/m(2)) and obesity (BMI ≥30 kg/m(2)) compared with normal BMI (18.5 to <25 kg/m(2)) with mortality after incident HF.

Among 1,487 patients with incident HF, 35% were overweight and 47% were obese by pre-morbid BMI measured 4.3 ± 3.1 years before HF diagnosis. Over 10-year follow-up after incident HF, 43% of patients died. After adjustment for demographics and comorbidities, being pre-morbidly overweight (hazard ratio [HR]: 0.72; 95% confidence interval [CI]: 0.58 to 0.90; p = 0.004) or obese (HR: 0.70; 95% CI: 0.56 to 0.87; p = 0.001) had a protective association with survival compared with normal BMI. The protective effect of overweight and obesity was consistent across subgroups on the basis of a history of cancer, smoking, and diabetes.

Our results, for the first time, demonstrate that patients who were overweight or obese before HF development have lower mortality after HF diagnosis compared with normal BMI patients. Thus, weight loss due to advanced HF may not completely explain the protective effect of higher BMI in HF patients.