Blood urea nitrogen variation upon admission and at discharge in patients with heart failure

Aims Heart failure (HF) is one of the leading causes for hospitalization and mortality. After first admission with acute decompensated HF, some patients are in high risk for short-term and long-term mortality. These patients should be identified, closely followed up, and treated. It has been observed that blood urea nitrogen (BUN) on admission is a predictive marker for short-term mortality. Recently, it has been shown that higher BUN levels on discharge are also a bad prognostic predictor. However, the prognostic value of BUN alteration during hospital stay was not investigated; therefore, we aimed to investigate the effect of BUN variation during hospitalization on mortality. Methods and results A retrospective study included patients with first hospitalization with the primary diagnosis of HF. The patients were divided into four groups on the basis of the values of BUN on admission and discharge, respectively: normal-normal, elevated-normal, normal-elevated, and elevated-elevated. Four thousand seven hundred sixty-eight patients were included; 2567 were male (53.8%); the mean age was 74.7 +/- 12.7 years. The 90 day mortality rate in the normal-normal group was 7% lower than that in the elevated-normal (14.6%) and normal-elevated (19.3%) groups; P value < 0.01. The 90 day mortality in the elevated-elevated group (28.8%) was significantly higher than that in the other groups; P < 0.001. During the 36 month follow-up, these results are maintained. While sub-dividing BUN levels into <30, 30-39, and >40 mg/dL, higher BUN levels correlated with higher 90 day mortality rate regardless of creatinine levels, brain natriuretic peptide, or age. Moreover, BUN on admission and on discharge correlated better with mortality than did creatinine and glomerular filtration rate at the same points. Conclusions The BUN both on admission and on discharge is a prognostic predictor in patients with HF; however, patients with elevated levels both on admission and on discharge have the worst prognosis. Moreover, worsening or lack of improvement in BUN during hospitalization is a worse prognostic predictor. To the best of our knowledge, this is the first trial to discuss the BUN change during hospitalization in HF.