Abnormal baseline and acutely worsening renal function (WRF) during heart failure (HF) hospitalization are associated with worse outcomes. However, which renal criterion is most predictive of in-hospital and post-discharge mortality is uncertain.
We analyzed patients hospitalized for HF between January 1, 2000 and June 30, 2008. Preexisting end-stage renal disease was excluded. Blood urea nitrogen (BUN), creatinine (Cr), and MDRD-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 criterion in terms of association with mortality.
Among 7,394 patients, 204 died in-hospital, and 1,652 within 1 year. Admission BUN was the strongest correlate for both in-hospital and post-discharge mortality (area under curve [AUC]= 0.724 and 0.656; p<0.001 vs. Cr/eGFR), showing 4.6 and 3.0 fold mortality, respectively. Adjusting for baseline BUN, subsequent changes in Cr and BUN performed similarly for in-hospital death (model AUC 0.812; p<0.001 vs. eGFR) and post-discharge death (all similar, model AUC=0.661). Optimally predictive thresholds of WRF in hospital were dependant on the baseline renal function, and did not always correspond to common definitions.
Among hospitalized HF patients, baseline BUN is the renal index most strongly associated with in-hospital and one year mortality. WRF definitions that use BUN or Cr, have similar discriminative ability overall, but commonly used thresholds are suboptimal for predicting mortality; optimal thresholds varied with baseline renal function and time horizon.