Body mass index and all-cause mortality in heart failure patients with normal and reduced ventricular ejection...

For patients with heart failure, there is an inverse relation between body mass index (BMI) and mortality, sometimes called the obesity-paradox. However, the relationship might be either U- or J-shaped and might differ between patients with reduced (HFrEF) or preserved left ventricular ejection fraction (HFpEF). We sought to investigate this further in a dose-response meta-analysis of published studies.

PubMed and Embase from June 1980 to April 2017 were searched for prospective cohort studies evaluating associations between BMI and all-cause mortality in patients with HFrEF (LVEF < 40%) or HFpEF (LVEF ≥ 50%). Summary estimated effect sizes were obtained by using a random-effects model. Potential non-linear relationships were evaluated by using random-effects restricted cubic spline models.

Ten studies were identified that included 96,424 patients of whom 59,263 had HFpEF (mean age 68 years of whom 38% were women) and 37,161 had HFrEF (mean age 60 years of whom 17% were women). For patients with HFpEF, the summary hazard ratio (HR) for all-cause mortality was: 0.93 (95% CI 0.89-0.97) per 5 units increase in BMI (I² = 75.8%, p for heterogeneity = 0.01 and Begg's test, p = 1.0, Egger's test, p = 0.29) but the association was U-shaped (p for non-linearity < 0.01) with the nadir of risk at a BMI of 32-33 kg/m². For patients with HFrEF, the summary HR for all-cause mortality was: 0.96 (95% CI 0.92-0.99) (I² = 95%, p for heterogeneity < 0.001 and Begg's test, p = 0.45, Egger's test, p = 0.01). The relationship was also U-shaped (p < 0.01), although 'flatter' than for HFpEF, with the nadir at a BMI of 33 kg/m².

For patients with heart failure, the relation between BMI and mortality is U-shaped with a similar nadir of risk for HFpEF and HFrEF at a BMI of 32-33 kg/m². Whether interventions that alter weight in either direction can alter risk is unknown.