Comparison of brain natriuretic peptide and probrain natriuretic peptide in the diagnosis of cardiogenic pulmonary edema in patients aged 65 and older.

OBJECTIVES: Differentiating cardiogenic pulmonary edema (CPE) from respiratory causes of dyspnea is difficult in elderly patients. The aim of this study was to compare the usefulness of B-type natriuretic peptide (BNP) and amino-terminal fragment BNP (proBNP), to diagnose CPE in patients aged 65 and older.

DESIGN: Prospective study.

SETTING: Medical emergency department of a 2,000-bed urban teaching hospital.

PARTICIPANTS: Patients aged 65 and older presenting with acute dyspnea and a respiratory rate of 25 breaths/min or greater, a partial pressure of oxygen of 70 mmHg or less, or an oxygen saturation of 92% or less were included.

MEASUREMENTS: Rapid BNP and proBNP assays, performed blind at admission, were compared with the final diagnosis (CPE or no CPE) as defined by an expert team.

RESULTS: Two hundred two patients (mean age+/-standard deviation 80+/-9) were included; 88 (44%) had CPE. There was a strong correlation between proBNP and BNP values (correlation coefficient=0.91, P<.001). The median BNP and proBNP were higher in the group of patients with CPE (377 vs 74 pg/mL, P<.001, and 3,851 vs 495 pg/mL, P<.001, respectively). The best threshold values of BNP and proBNP were 250 pg/mL and 1,500 pg/mL, respectively. The area under the receiver operating characteristic curve was greater with BNP than with proBNP (0.85 vs 0.80, P<.05). BNP assay was more accurate in diagnosis than the emergency physician, whereas proBNP was not. Higher values of BNP and proBNP were associated with greater in-hospital mortality.

CONCLUSION: BNP assay is a more useful diagnostic indicator for CPE than proBNP in patients aged 65 and older.