Impact of Body Mass Index on outcomes in hospitalized heart failure patients with reduced versus preserved ejection fraction: a 1,699,494-individual analysis from the United States National Inpatient Sample.

Background: Obesity's effect on outcomes in heart failure (HF) patients with reduced versus maintained ejection fraction (HFrEF and HFpEF) remains debatable. We evaluated hospital outcomes and healthcare expenditures in these patients based on their Body Mass Index (BMI).

Methods: Using the USA National Inpatient Sample (NIS) database, patients >18 years admitted with a primary diagnosis of HFrEF or HFpEF between January 1, 2004, and August 31, 2015, were studied. Patients were stratified into the following BMI categories: underweight, normal weight, overweight, obese, and morbidly obese. Adjusted multivariable analyses using Poisson regression models were used to study the association between BMI and hospital outcomes and healthcare costs.

Results: Overall, 1,699,494 patients were included. After full adjustment, obesity (OR=1.84; 95% CI: 1.22-2.76) and morbid obesity (OR=1.81; 95% CI: 1.22-2.70) increased the odds of in-hospital mortality compared with normal weight. When stratified per ejection fraction, underweight patients had higher odds of in-hospital mortality in HFrEF (OR=1.46; 95% CI: 1.06-2.01). Obese and morbidly obese patients had higher odds of in-hospital mortality in both HFrEF and HFpEF. Furthermore, obese and morbidly obese patients had a longer mean adjusted length of stay and higher health care expenses.

Conclusions: Being underweight is associated with increased risk of in-hospital mortality in HFrEF patients. Obesity and morbid obesity increase the risk of in-hospital mortality and higher healthcare costs in both HFrEF and HFpEF. These findings have clinical significance for HF patients, and further research is needed to investigate the ideal weight for HF patients.