Prognostic Importance of Serial Evaluation of Blood Urea Nitrogen in Ambulatory Patients with Chronic Systolic Heart Failure and Preserved Renal Function
Journal of Cardiac Failure
Background: Serum blood urea nitrogen (BUN) has been considered as the single most important prognostic marker in patients admitted to hospital with decompensated heart failure(HF). However, its ability to provide incremental information in serial measures in the ambulatory setting in the absence of renal dysfunction has not been carefully studied. We sought to examine the prognostic value of baseline and serial serum BUN levels in ambulatory patients with chronic systolic HF with preserved renal function at baseline and at follow-up. Methods: We identified 1582 consecutive ambulatory patients with documented chronic systolic HF (left ventricular ejection fraction [LVEF] <50%) with serial serum BUN and creatinine (Cr) measurements, estimated glomerular filtration rate (eGFR) ≥60 and evaluated the impact of these changes from baseline to 6-24 months on subsequent long-term outcome in patients with normal GFR. Results: In our study cohort (mean age 62 ± 14 years, 71% male, mean LVEF 25 ± 10%), the median BUN was 18 mg/dL (IQR 14-22; 12% had BUN>25 mg/dL or “High”) mg/dL and the mean Cr was 0.95 ± 0.4 mg/dL. Ninety-three (6%) of those with elevated baseline BUN had persistent elevation (High→High) and 35 (2.8%) had persistently elevated BUN but preserved renal function (GFR>60). In patients with persistently elevated BUN and preserved renal function, the increased adjusted mortality risk was 55% over those with normal baseline and follow-up BUN (Low→Low). In contrast, 16% experienced worsening from baseline normal BUN (Low→High) still demonstrated higher mortality risk than those improved from high BUN (High→Low). Conclusion: In ambulatory patients with chronic systolic heart failure, rise in serum BUN over time portends poor long-term prognosis, despite preserved glomerular filtration at baseline and at follow-up.
Cauthen, Clay A.; Tong, Matthew; Wu, Yuping; Jain, Anil; and Tang, W.H. Wilson, "Prognostic Importance of Serial Evaluation of Blood Urea Nitrogen in Ambulatory Patients with Chronic Systolic Heart Failure and Preserved Renal Function" (2011). Mathematics Faculty Publications. 147.