Impact of Body Mass Index on Heart Failure by Race/Ethnicity From the Get With The Guidelines-Heart Failure (GWTG-HF) Registry

Abstract

Objectives: This study sought to evaluate the influence of race/ethnicity on the relationship between body mass index (BMI) and mortality in heart failure with preserved ejection fraction (HFpEF) and HF with reduced EF (HFrEF) patients.

Background: Prior studies demonstrated an "obesity paradox" among overweight and obese patients, where they have a better HF prognosis than normal weight patients. Less is known about the relationship between BMI and mortality among diverse patients with HF, particularly given disparities in obesity and HF prevalence.

Methods: The authors used Get With The Guidelines-Heart Failure data to assess the relationship between BMI and in-hospital mortality by using logistic regression modeling. The authors assessed 30-day and 1-year rates of all-cause mortality following discharge by using Cox regression modeling.

Results: A total of 39,647 patients with HF were included (32,434 [81.8%] white subjects; 3,809 [9.6%] black subjects; 1,928 [4.9%] Hispanic subjects; 544 [1.4%] Asian subjects; and 932 [2.3%] other subjects); 59.7% of subjects had HFpEF, and 30.7% were obese. More black and Hispanic patients had Class I or higher obesity (BMI ≥30 kg/m²) than whites, Asians, or other racial/ethnic groups (p < 0.0001). Among subjects with HFpEF, higher BMI was associated with lower 30-day mortality, up to 30 kg/m² with a small risk increase above 30 kg/m² (BMI: 30 vs. 18.5 kg/m²), hazard ratio (HR) of 0.63 (95% confidence interval [CI]: 0.54 to 0.73). A modest relationship was observed in HFrEF subjects (BMI: 30 vs. 18.5 kg/m²; HR: 0.73; 95% CI: 0.60 to 0.89), with no risk increase above 30 kg/m². There were no significant interactions between BMI and race or ethnicity related to 30-day mortality (p > 0.05).

Conclusions: This work is one of the first suggesting the obesity paradox for 30-day mortality exists at all BMI levels in HFrEF but not in patients with HFpEF. Higher BMI was associated with lower 30-day mortality across racial/ethnic groups in a manner inconsistent with the J-shaped relationship noted for coronary artery disease. The differential slope of obesity and mortality among HFpEF and patients with HFrEF potentially suggests differing mechanistic factors, requiring further exploration.

Keywords: GWTG-Heart Failure; ethnicity; heart failure; mortality; obesity; race.

Figure 1. Flow diagram of the study population selection process

Participants were excluded systematically from the original GWTG-HF cohort.

Figure 2. Mean BMI by race/ethnicity among HFpEF and HFrEF patients, GWTG-HF, 2005–2011

Gray bars represent patients with HFpEF, while blue bars represent patients with HFrEF. Error bars represent standard deviation.

Figure 3. Adjusted Association between Body Mass Index and 30-day Mortality for HFpEF Patients, GWTG-HF, 2005–2011

Among HFpEF patients, higher BMI was associated with lower 30-day all-cause mortality up to 30 kg/m² with little change in risk above 30 kg/m².

Figure 4. Adjusted Association between Body Mass Index and 30-day Mortality for HFrEF Patients, GWTG-HF, 2005–2011

Up to a BMI of 30 kg/m², 30-day all-cause mortality decreased with every BMI unit increase (BMI=30 kg/m² vs BMI=18.5 kg/m² HR 0.73, 95% CI:0.60–0.89).