Objectives: Abnormal baseline and acutely worsening renal function (WRF) during heart failure hospitalization are associated with worse outcomes. However, which renal criterion is most predictive of in-hospital and postdischarge mortality is uncertain.
Methods: We analyzed patients hospitalized for heart failure between 1 January 2000 and 30 June 2008. Preexisting end-stage renal disease was excluded. Blood urea nitrogen (BUN), creatinine, and modification of diet in renal disease-estimated glomerular filtration rate (eGFR) at admission and during hospitalization were tested for association with in-hospital and 1-year mortality. Logistic regression and conditional receiver operating curves were used to compare criteria in terms of association with mortality.
Results: Among 7394 patients, 204 died in-hospital and 1652 within 1 year. Admission BUN was the strongest correlate for both in-hospital and postdischarge mortality [area under the curve (AUC) = 0.724 and 0.656; P < 0.001 vs. creatinine/eGFR], showing 4.6-fold and 3.0-fold mortality, respectively. Adjusting for baseline BUN, subsequent changes in creatinine and BUN performed similarly for in-hospital death (model AUC 0.812; P < 0.001 vs. eGFR) and postdischarge death (all similar, model AUC = 0.661). Optimally predictive thresholds of WRF in hospital were dependent on the baseline renal function and did not always correspond to common definitions.
Conclusion: Among hospitalized heart failure patients, baseline BUN is the renal index most strongly associated with in-hospital and 1-year mortality. WRF definitions that use BUN or creatinine have similar discriminative ability overall, but commonly used thresholds are suboptimal for predicting mortality; optimal thresholds varied with baseline renal function and time horizon.