Table_1_Elevated Blood Urea Nitrogen to Serum Albumin Ratio Is an Adverse Prognostic Predictor for Patients Undergoing Cardiac Surgery.doc

BackgroundElevated blood urea nitrogen (BUN) and reduced albumin have been prominently correlated with unfavorable outcomes in patients with cardiovascular diseases. However, whether combination BUN and albumin levels could predict the adverse outcomes of cardiac surgery patients remains to be confirmed. Here, we investigated the prognostic effect of the preoperative BUN to serum albumin ratio (BAR) in cardiac surgery patients.
MethodsData were obtained from the Medical Information Mart for Intensive Care (MIMIC) III and eICU databases and classified into a training cohort and validation cohort. The BAR (mg/g) was calculated by initial BUN (mg/dl)/serum albumin (g/dl). The primary outcome was in-hospital mortality. Secondary outcomes were 1-year mortality, prolonged length at intensive care unit, and duration of hospital stay. The associations of BAR with outcomes were explored by multivariate regression analysis and subgroup analyses. Then, C statistics were performed to assess the added prognostic impact of BAR beyond a baseline risk model.
ResultsPatients with in-hospital death had significantly higher levels of BAR. Multivariate regression analysis identified BAR, as a categorical or continuous variable, as an independent factor for adverse outcomes of cardiac surgery (all p < 0.05). Subgroup analyses demonstrated a significant relationship between elevated BAR and in-hospital mortality in different subclasses. The addition of BAR to a baseline model provided additional prognostic information benefits for assessing primary outcome. Results were concordant in the external validation cohort.
ConclusionsIncreased preoperative BAR is a potent predictor of unfavorable outcomes in patients undergoing cardiac surgery.

研究背景：血尿素氮（blood urea nitrogen, BUN）升高与白蛋白降低已被证实与心血管疾病患者的不良预后显著相关。然而，联合检测BUN与白蛋白水平能否预测心脏手术患者的不良预后，仍有待证实。本研究旨在探讨术前血尿素氮与血清白蛋白比值（BUN to serum albumin ratio, BAR）对心脏手术患者的预后价值。

研究方法：本研究数据来源于重症监护医疗信息集市（Medical Information Mart for Intensive Care, MIMIC）III及eICU数据库，按分组规则划分为训练队列与验证队列。BAR（单位：mg/g）以初始BUN（单位：mg/dl）除以血清白蛋白（单位：g/dl）计算得出。主要结局指标为住院期间死亡率，次要结局指标包括1年死亡率、重症监护病房停留时间延长及住院总时长。采用多因素回归分析与亚组分析探讨BAR与各结局指标的关联；随后通过C统计量评估在基线风险模型基础上加入BAR后所额外带来的预后评估价值。

研究结果：发生住院期间死亡的患者，其BAR水平显著更高。多因素回归分析显示，无论以分类变量还是连续变量形式纳入分析，BAR均为心脏手术患者不良预后的独立危险因素（所有p<0.05）。亚组分析表明，在各亚组中，BAR升高均与住院期间死亡率存在显著关联。在基线模型中加入BAR，可提升对主要结局指标的预后评估效能；该结果在外部验证队列中亦得到一致验证。

研究结论：术前BAR升高可作为心脏手术患者不良预后的强有力预测因子。