Serum retinol-binding protein 4 as a predictor of cardiovascular events in elderly patients with chronic heart failure

Aims RBP4 is an adipokine with adverse effects on cardiovascular system. Increased circulating retinol-binding protein 4 (RBP4) has been linked to chronic heart failure (CHF). However, whether elevated RBP4 is correlated with a poor prognosis in elderly patients with CHF remains unclear. The aim of this study was to evaluate the prognostic value of serum RBP4 in elderly patients with CHF. Methods and results We enrolled 934 consecutive elderly patients (aged 60 years and older) with CHF and 138 age-matched and sex-matched control subjects in a prospective cohort study and explored the association of serum RBP4 levels with the clinical outcomes using multivariate Cox regression analyses. Serum RBP4 levels were elevated in CHF patients when compared with controls (46.66 +/- 12.38 mu g/mL vs. 40.71 +/- 7.2 mu g/mL, P < 0.001). Patients with the highest RBP4 concentrations had higher N terminal pro brain natriuretic peptide (NT-proBNP) levels but lower left ventricular eject fraction (LVEF) and estimated glomerular filtration rate (P < 0.001). Serum RBP4 levels were increased as the New York Heart Association functional class increased and LVEF decreased (P < 0.001) and were negatively correlated with LVEF (r = -0.154, P < 0.001) but positively correlated with NT-proBNP levels (r = 0.074, P = 0.023). Multivariate Cox regression analysis suggested that log RBP4 was an independent predictor for major adverse cardiac event(s) [hazard ratio (HR) = 2.61, 95% confidence interval (CI) = 1.19-5.70], together with age, male, LVEF, log NT-proBNP, and estimated glomerular filtration rate. Moreover, log RBP4 was also an independent predictor for cardiovascular mortality (HR = 2.24, 95% CI = 1.35-5.39) and CHF rehospitalization (HR = 2.54, 95% CI = 1.09-5.60) even after adjustment for the established adverse prognostic factors for CHF. The Kaplan-Meier survival curves showed that high concentration of RBP4 was a prognostic indicator of major adverse cardiac event(s) in patients with CHF. Conclusions Our findings demonstrate for the first time that elevated serum RBP4 is correlated with worse outcome in elderly patients with CHF.