eGFR and Outcomes in Patients with Acute Decompensated Heart Failure with or without Elevated BUN

Abstract

Background and objectives: In patients with heart failure, the association of renal dysfunction and BUN levels with outcomes is unclear. The aim of our study was to investigate the association between the eGFR at discharge and outcomes in patients with heart failure with or without an elevated BUN level at discharge.

Design, setting, participants, & measurements: Of 4842 patients enrolled in the Acute Decompensated Heart Failure Syndromes Registry, 4449 patients discharged alive after hospitalization for acute decompensated heart failure were investigated to assess the association of eGFR in the context of serum BUN level at discharge with all-cause mortality. The enrolled patients were divided into four groups on the basis of the discharge levels of eGFR (<45 or ≥45 ml/min per 1.73 m(2)) and BUN (≥25 or <25 mg/dl). The median follow-up period after discharge was 517 (381-776) days.

Results: The all-cause mortality rate after discharge was 19.1%. After adjustment for multiple comorbidities, an eGFR<45 ml/min per 1.73 m(2) was associated with a significantly higher risk of all-cause mortality in patients with a BUN≥25 mg/dl (hazard ratio, 1.58; 95% confidence interval, 1.33 to 1.88; P<0.001) but not in patients with a BUN<25 mg/dl (hazard ratio, 0.97; 95% confidence interval, 0.76 to 1.26; P=0.84) relative to those with an eGFR≥45 ml/min per 1.73 m(2) and a BUN<25 mg/dl. Among patients with an eGFR≥45 ml/min per 1.73 m(2), a BUN≥25 mg/dl was associated with a significantly higher risk of all-cause mortality than a BUN<25 mg/dl (hazard ratio, 1.34; 95% confidence interval, 1.04 to 1.73; P=0.02).

Conclusions: We showed that elevation of BUN at discharge significantly modified the relation between eGFR at discharge and the risk of all-cause mortality after discharge, suggesting that the association between eGFR and outcomes may be largely dependent on concomitant elevation of BUN.

Keywords: Comorbidity; Follow-Up Studies; Humans; Patient Discharge; Registries; blood urea nitrogen; glomerular filtration rate; heart failure; hospitalization; outcomes assessment.

Figure 1.

Receiver-operating characteristic curves of eGFR at discharge and BUN at discharge predicting the all-cause mortality after discharge in patients with acute decompensated heart failure (HF). (A) Receiver-operating characteristic curve of eGFR at discharge. (B) Receiver-operating characteristic curve of BUN at discharge. Circles indicate the optimum cutoff values. AUC, area under the receiver–operating characteristic curve; 95% CI, 95% confidence interval.

Figure 2.

Kaplan–Meier estimates of all-cause death after discharge in four groups stratified by the eGFR and BUN at discharge. Numbers at risk were given in the lower part.

Figure 3.

Kaplan–Meier estimates of cardiac death after discharge in four groups stratified by the eGFR and BUN at discharge. Numbers at risk were given in the lower part.