Interaction of Body Mass Index on the Association Between N‐Terminal‐Pro‐b‐Type Natriuretic Peptide and Morbidity and Mortality in Patients With Acute Heart Failure: Findings From ASCEND‐HF (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated Heart Failure)

BACKGROUND Higher body mass index (BMI) is associated with lower circulating levels of N-terminal-pro-b-type natriuretic peptide (NT-proBNP). The Interaction between BMI and NT-proBNP with respect to clinical outcomes is not well characterized in patients with acute heart failure. METHODS AND RESULTS A total of 686 patients from the biomarker substudy of the ASCEND-HF (Acute Study of Clinical Effectiveness of Nesiritide in Decompensated HF ) clinical trial with documented NT-proBNP levels at baseline were included in the present analysis. Patients were classified by the World Health Organization obesity classification (nonobese: BMI <30 kg/m2, Class I obesity: BMI 30-34.9 kg/m2, Class II obesity BMI 35-39.9 kg/m2, and Class III obesity BMI ≥40 kg/m2). We assessed baseline characteristics and 30- and 180-day outcomes by BMI class and explored the interaction between BMI and NT-proBNP for these outcomes. Study participants had a median age of 67 years (55, 78) and 71% were female. NT-proBNP levels were inversely correlated with BMI (P<0.001). Higher NT-proBNP levels were associated with higher 180-day mortality (adjusted hazard ratio for each doubling of NT-proBNP, 1.40; 95% confidence interval, 1.16, 1.71; P<0.001), but not 30-day outcomes. The effect of NT-proBNP on 180-day death was not modified by BMI class (interaction P=0.24). CONCLUSIONS The prognostic value of NT-proBNP was not modified by BMI in this acute heart failure population. NT-proBNP remains a useful prognostic indicator of long-term mortality in acute heart failure even in the obese patient. CLINICAL TRIAL REGISTRATION URL: http://www.clinicaltrials.gov. Unique identifier: NCT00475852.