The relationship between N-terminal pro-brain natriuretic peptide and risk for hospitalization and mortality is curvilinear in patients with chronic heart failure

Abstract

Background: N-terminal pro-brain natriuretic peptide (NT-proBNP) carries prognostic information in patients with chronic heart failure and predicts risk for mortality and cardiovascular events. It is unknown whether NT-proBNP predicts risk for hospitalization for any cause. Furthermore, a clinically useful algorithm for risk stratification based on NT-proBNP as a continuous variable has not yet been described. We therefore evaluated NT-proBNP as a risk marker for mortality and hospitalization and developed a simple algorithm for risk stratification based on NT-proBNP as a continuous variable.

Methods: Data from 345 patients with chronic heart failure were collected prospectively in our heart failure clinic, and the patients were followed for 28 months (median). Seventy patients died, and 201 patients were hospitalized. Cox proportional hazard models for mortality and hospitalization were constructed with NT-proBNP as a dichotomous (median 1381 pg/mL) and a continuous variable (log2 NT-proBNP).

Results: Patients with supramedian levels of NT-proBNP had a 2.40-fold (95% CI 1.40-4.10) increased risk for mortality and 1.71-fold (95% CI 1.24-2.36) increased risk for hospitalization. The effect of doubling NT-proBNP on adjusted hazard ratios was 1.56 (95% CI 1.32-1.85) for mortality and 1.19 (95% CI 1.09-1.31) for hospitalization. We observed a curvilinear relationship between NT-proBNP and risk for mortality and hospitalization in the whole range of NT-proBNP.

Conclusions: N-terminal pro-brain natriuretic peptide predicts risk for hospitalization and mortality. A simple algorithm indicates that every time NT-proBNP is doubled, estimated hazard ratio for death increases by a factor of 1.56 (56%) and by a factor of 1.19 (19%) for hospitalization. Finally, the relationship between NT-proBNP and risk is curvilinear if NT-proBNP is considered as a continuous variable.