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

Background/Objectives: 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. Subjects/Methods: 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). Results: 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. Conclusions: 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.