Blood urea nitrogen to albumin ratio is a predictor of in-hospital mortality in older emergency department patients.

Introduction: In this study, we aimed to evaluate the first measured blood urea nitrogen (BUN)/albumin ratio in the emergency department (ED) as a predictor of in-hospital mortality in older ED patients.

Methods: This retrospective observational study was conducted at a university hospital ED. Consecutive patients aged 65 and over who visited the ED in a three-month period were included in the study. The BUN, albumin, creatinine, and estimated glomerular filtration rate (eGFR) of patients were recorded. The primary end point of the study was in-hospital mortality.

Results: A total of 1253 patients were included in the statistical analyses of the study. Non-survivors had increased BUN levels (32.9 (23.3-55.4) vs. 20.2 (15.4-28.3) mg/dL, p < 0.001), decreased albumin levels (3.27 (2.74-3.75) vs. 3.96 (3.52-4.25) g/dL, p < 0.001), and increased BUN/albumin ratios (10.19 (6.56-18.94) vs. 5.21 (3.88-7.72) mg/g, p < 0.001) compared to survivors. An increased BUN/albumin ratio was a powerful predictor of in-hospital mortality with an area under the curve of 0.793 (95% CI: 0.753-0.833). Malignancy (OR: 2.39; 95% CI: 1.59-3.74, p < 0.001), albumin level < 3.5 g/dL (OR: 2.75; 95% CI: 1.74-4.36, p < 0.001), and BUN/albumin ratio > 6.25 (OR: 2.82; 95% CI: 1.22-6.50, p < 0.015) were found to be independent predictors of in-hospital mortality in older ED patients.

Conclusion: According to our findings, older patients with a BUN level > 23 mg/dL, an albumin level < 3.5 g/dL, and a BUN/albumin ratio > 6.25 mg/g in the ED have a higher risk of in-hospital mortality. Additionally, the BUN/albumin ratio is a more powerful independent predictor of in-hospital mortality than the BUN level, albumin level, creatinine level, and eGFR in older ED patients.