NT-proBNP for Risk Prediction in Heart Failure: Identification of Optimal Cutoffs Across Body Mass Index Categories.

OBJECTIVES: The goal of this study was to assess the predictive power of N-terminal pro-B-type natriuretic peptide (NT-proBNP) and the decision cutoffs in heart failure (HF) across body mass index (BMI) categories. BACKGROUND: Concentrations of NT-proBNP predict outcome in HF. Although the influence of BMI to reduce levels of NT-proBNP is known, the impact of obesity on prognostic value remains uncertain. METHODS: Individual data from the BIOS (Biomarkers In Heart Failure Outpatient Study) consortium were analyzed. Patients with stable HF were classified as underweight (BMI <18.5 kg/m2), normal weight (BMI 18.5-24.9 kg/m2), overweight (BMI 25-29.9 kg/m2), and mildly (BMI 30-34.9 kg/m2), moderately (BMI 35-39.9 kg/m2), or severely (BMI ≥40 kg/m2) obese. The prognostic role of NT-proBNP was tested for the endpoints of all-cause and cardiac death. RESULTS: The study population included 12,763 patients (mean age 66 ± 12 years; 25% women; mean left ventricular ejection fraction 33% ± 13%). Most patients were overweight (n = 5,176), followed by normal weight (n = 4,299), mildly obese (n = 2,157), moderately obese (n = 612), severely obese (n = 314), and underweight (n = 205). NT-proBNP inversely correlated with BMI (ß = -0.174 for 1 kg/m2; P < 0.001). Adding NT-proBNP to clinical models improved risk prediction across BMI categories, with the exception of severely obese patients. The best cutoffs of NT-proBNP for 5-year all-cause death prediction were lower as BMI increased (3,785 ng/L, 2,193 ng/L, 1,554 ng/L, 1,045 ng/L, 755 ng/L, and 879 ng/L, for underweight, normal weight, overweight, and mildly, moderately, and severely obese patients, respectively) and were higher in women than in men. CONCLUSIONS: NT-proBNP maintains its independent prognostic value up to 40 kg/m2 BMI, and lower optimal risk-prediction cutoffs are observed in overweight and obese patients.

Circulating levels and prognostic value of soluble ST2 in heart failure are less influenced by age than N-terminal pro-B-type natriuretic peptide and high-sensitivity troponin T.

AIMS: N-terminal pro-B-type natriuretic peptide (NT-proBNP), high-sensitivity troponin T (hs-TnT) and soluble suppression of tumorigenesis-2 (sST2) predict outcome in chronic heart failure (HF). We assessed the influence of age on circulating levels and prognostic significance of these biomarkers. METHODS AND RESULTS: Individual data from 5301 patients with chronic HF and NT-proBNP, hs-TnT, and sST2 data were evaluated. Patients were stratified according to age: <60 years (n = 1332, 25%), 60-69 years (n = 1628, 31%), 70-79 years (n = 1662, 31%), and ≥ 80 years (n = 679, 13%). Patients (median age 66 years, 75% men, median left ventricular ejection fraction 28%, 64% with ischaemic HF) had median NT-proBNP 1564 ng/L, hs-TnT 21 ng/L, and sST2 29 ng/mL. Age independently predicted NT-proBNP and hs-TnT, but not sST2. The best NT-proBNP and hs-TnT cut-offs for 1-year and 5-year all-cause and cardiovascular mortality and 1- to 12-month HF hospitalization increased with age, while the best sST2 cut-offs did not. When stratifying patients according to age- and outcome-specific cut-offs, this stratification yielded independent prognostic significance over NT-proBNP levels only, or the composite of NT-proBNP and hs-TnT, and improved risk prediction for most endpoints. Finally, absolute NT-proBNP, hs-TnT, and sST2 levels predicted outcomes independent of age, sex, left ventricular ejection fraction category, ethnic group, and other variables. CONCLUSIONS: Soluble ST2 is less influenced by age than NT-proBNP or hs-TnT; all these biomarkers predict outcome regardless of age. The use of age- and outcome-specific cut-offs of NT-proBNP, hs-TnT and sST2 allows more accurate risk stratification than NT-proBNP alone or the combination of NT-proBNP and hs-TnT.