The Blood Urea Nitrogen to Creatinine Ratio Identifies a High Risk but Potentially Reversible Form of Renal Dysfunction in Patients with Decompensated Heart Failure Brisco et al: BUN/Cr and Reversible Renal Dysfunction

Background—Identifying reversible renal dysfunction (RD) in the setting of heart failure (HF) is challenging. The goal of this study was to evaluate if an elevated admission blood urea nitrogen to creatinine ratio (BUN/Cr) could identify decompensated HF patients likely to experience improvement in renal function (IRF) with treatment. Methods and Results—Consecutive hospitalizations with a discharge diagnosis of HF were reviewed. IRF was defined as 20% increase and worsening renal function (WRF) 20% decrease in estimated glomerular filtration rate (eGFR). IRF occurred in 31% of the 896 patients meeting eligibility criteria. Higher admission BUN/Cr was associated with in-hospital IRF (OR=1.5 per 10 increase, 95% CI: 1.3-1.8, p<0.001), an association persisting after adjustment for baseline characteristics (OR=1.4, 95% CI: 1.1-1.8, p=0.004). However, higher admission BUN/Cr was also associated with post-discharge WRF (OR= 1.4, 95% CI: 1.1-1.8, p=0.011). Notably, in patients with an elevated admission BUN/Cr, the risk of death associated with RD (eGFR<45) was substantial (HR=2.2, 95% CI: 1.6-3.1, p<0.001). However, in patients with a normal admission BUN/Cr, RD was not associated with increased mortality (HR=1.2, 95% CI: 0.67-2.0, p=0.59, p interaction= 0.03). Conclusions—An elevated admission BUN/Cr identifies decompensated HF patients likely to experience IRF with treatment, providing proof of concept that reversible RD may be a discernible entity. However, this improvement appears to be largely transient and RD in the setting of an elevated BUN/Cr remains strongly associated with death. Further research is warranted to develop strategies for the optimal detection and treatment of these high-risk patients.