Body mass index and all-cause readmissions following acute heart failure hospitalization.

Abstract

Obesity is associated with a lower mortality risk among patients with heart failure (HF). Whether this obesity paradox applies to all-cause hospitalizations is unknown. We aimed to investigate the association between body mass index (BMI) and 30-day all-cause readmissions following HF hospitalization. We retrospectively evaluated 2252 HF hospital admissions of Centers of Medicare Services beneficiaries from an academic medical center. We classified obesity using established BMI categories. All 30-day postdischarge readmission to all hospitals and mortality events were documented. We evaluated 30-day postdischarge unplanned, all-cause readmission and death in the total cohort, propensity-matched cohort, and by ejection fraction (EF). An Overweight-Obese BMI (BMI ≥ 25 kg/m2) was paradoxically associated with a lower mortality rate than a Normal BMI (18.5-24.9 kg/m2) (5.0% vs 8.5%, p = 0.0018). In contrast, an Overweight-Obese BMI was associated with a 29% (95% CI: 1.03-1.63) increased relative risk of all-cause readmission compared with a Normal BMI (23.2% vs 18.9%, p = 0.0288), which was consistent across obesity severity subgroups. Among 966 matched admissions, an Overweight-Obese BMI retained higher readmission risk compared with a Normal BMI (25.1% vs 17.2%, p = 0.003). After matching, readmissions remained higher for Overweight-Obese vs Normal BMI in admissions with reduced EF (25.7% vs 17.8%, p = 0.032) and preserved EF (23.0% vs 15.0%, p = 0.048). No difference in the percentage of readmissions for HF (40%) or noncardiovascular causes (45%) existed between Overweight-Obese and Normal BMI groups. Despite a lower mortality risk, increased BMI is associated with increased all-cause hospital readmission rates in an elderly HF population which persists after propensity matching.