Clinical study
Elevated blood urea nitrogen level as a predictor of mortality in patients admitted for decompensated heart failure

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Abstract

Background

Hospitalization for decompensated heart failure is associated with high mortality after discharge. In heart failure, renal function involves both cardiovascular and hemodynamic properties. We studied the relation between renal dysfunction and mortality in patients admitted for decompensated heart failure.

Methods

The prognostic importance of four measures of renal function—blood urea nitrogen, serum creatinine, blood urea nitrogen/creatinine ratio, and estimated creatinine clearance—was evaluated in 541 patients (mean [± SD] age, 63 ± 14 years; 377 men [70%]) with a previous diagnosis of heart failure (96% with New York Heart Association class III or IV symptoms) who were admitted for clinical decompensation.

Results

During a mean follow-up of 343 ± 185 days, 177 patients (33%) died. In multivariable Cox regression models, the risk of all-cause mortality increased with each quartile of blood urea nitrogen, with an adjusted relative risk of 2.3 in patients in the upper compared with the lower quartiles (95% confidence interval [CI]: 1.3 to 4.1; P = 0.005). Creatinine and estimated creatinine clearance were not significant predictors of mortality after adjustment for other covariates. Blood urea nitrogen/creatinine ratio yielded similar prognostic information as blood urea nitrogen (adjusted relative risk = 2.3; 95% CI: 1.4 to 3.8; P = 0.0007 for patients in the upper compared with the lower quartiles).

Conclusion

Blood urea nitrogen is a simple clinical variable that provides useful prognostic information in patients admitted for decompensated heart failure. In this setting, elevated blood urea nitrogen levels probably reflect the cumulative effects of hemodynamic and neurohormonal alterations that result in renal hypoperfusion.

Section snippets

Patients

We performed a pooled analysis of the Comparative trial (11) and the Prospective Randomized Evaluation of Cardiac Ectopy with Dobutamine or Nesiritide Therapy (PRECEDENT) study (12), two randomized trials of nesiritide (human B-type natriuretic peptide) in patients with decompensated heart failure. The study protocols have been described in detail elsewhere 11, 12. In brief, in the Comparative trial (11), 305 patients admitted for acute decompensated heart failure were randomly assigned to

Results

Baseline clinical characteristics were similar among the patients in the two trials, with the exception that more patients in the PRECEDENT trial received digoxin, beta-blockers, and ACE inhibitors or angiotensin II receptor inhibitors (Table 1).

Discussion

In the present study, we sought to determine whether the severity of renal dysfunction in hospitalized patients with decompensated heart failure provided prognostic information on outcomes after discharge. We found blood urea nitrogen and the blood urea nitrogen/creatinine ratio to be independent predictors of all-cause mortality. Serum creatinine and estimated creatinine clearance were not associated with mortality after adjustment for other covariates.

Renal function is an important

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