Role of blood urea nitrogen in predicting the post-discharge prognosis in elderly patients with acute decompensated heart failure.

ABSTRACT

Blood urea nitrogen (BUN) is a surrogate marker for neurohormonal activation, but the association between BUN and the post-discharge prognosis in elderly patients with acute decompensated heart failure (ADHF) is not well defined. We explored the association between BUN and post-discharge all-cause mortality in 652 elderly patients (73.9 ± 7.8 yr) with ADHF. All patients were followed for a mean duration of 32 months (12-69 months). BUN was analyzed both as a continuous variable and according to two categories low BUN group (BUN < 15.35 mmol/L, N = 361) and high BUN group (BUN ≥ 15.35 mmol/L, N = 291). The risk of all-cause mortality increased by 1.6% per 1 mmol/L increase in BUN concentration when BUN was used as a continuous variable [hazard ratio (HR) 1.016, 95% confidence interval (CI) 1.006-1.026, p = 0.002]. BUN maintained an independent and significant positive correlation with all-cause mortality as a categorical variable (HR 1.355, 95% CI 1.023-1.794, p = 0.034 for the high BUN group). The BUN C-statistic for predicting all-cause mortality was 0.624 (95% CI 0.585-0.661). The cut-off value for BUN was 15.35 mmol/L with sensitivity of 0.58 and specificity of 0.63. The prognostic performance of BUN was similar to brain natriuretic peptide (BNP) for predicting all-cause mortality (C-statistic z = 0.044, p = 0.965). These results suggest that BUN is an independent predictor of post-discharge all-cause mortality in elderly patients with ADHF and its prognostic performance was similar to that of BNP.