Association between fibrinogen-to-albumin ratio and prognosis in patients admitted to an intensive care unit

Background: The objective of this study was to investigate the usefulness of fibrinogen-to-albumin ratio (FAR) as a prognostic marker in patients admitted to an intensive care unit (ICU) compared with Sequential Organ Failure Assessment (SOFA) score, a widely used prognostic scoring system. Methods: Using a total of 18,562 consecutive adult patients who were admitted to ICU with available fibrinogen and albumin levels from June 2013 to May 2022. An inverse probability weighting (IPW) was used to control for selection bias and confounding factors. After estimating an optimal threshold, patients were divided accordingly, and 1-year mortality was compared. Results: One-year mortality was higher in 3rd tertile of FAR group compared with 1st and 2nd tertile of FAR groups (35.9%, 11.5%, and 13.3%, respectively). The threshold of FAR value was estimated to be 10.79 with the area under the curve of 0.68. According to the estimated threshold, patients were divided into a low FAR group (n = 12,533, 67.5%) and a high FAR group (n = 6,029, 32.5%). After IPW adjustment, the high FAR group showed significantly higher risk of 1-year compared with low FAR group (36.4% vs. 12.4%, adjust hazard ratio = 1.72; 95% confidence interval (CI): 1.59–1.86; P < 0.001). However, in the receiver-operating characteristic curve analysis associated with the prediction of 1-year mortality, there was no significant difference between the area under the curve of FAR on ICU admission (C-statistic: 0.684, 95% CI: 0.673 – 0.694) and that of SOFA score on ICU admission (C-statistic: 0.679, 95% CI: 0.669 – 0.688) (P = 0.532). Conclusions: In this study, FAR and SOFA score at ICU admission were associated with 1-year mortality in patients admitted to an ICU. Especially, FAR was easier to obtain in critically ill patients than SOFA score. Therefore, FAR is feasible and reliable in predicting long-term mortality in these patients.

研究背景：本研究旨在探讨纤维蛋白原与白蛋白比值（fibrinogen-to-albumin ratio, FAR）作为重症监护病房（intensive care unit, ICU）收治患者预后标志物的应用价值，并与当前广泛使用的预后评分系统——序贯器官衰竭评估（Sequential Organ Failure Assessment, SOFA）评分进行对比。研究方法：本研究纳入2013年6月至2022年5月期间于ICU收治的、具备完整纤维蛋白原与白蛋白检测数据的连续成年患者共18562例。采用逆概率加权法（inverse probability weighting, IPW）控制选择偏倚与混杂因素。在确定最优截断值后，按该阈值将患者分组，并比较各组的1年死亡率。研究结果：纤维蛋白原与白蛋白比值三分位组中，第三三分位组的1年死亡率（35.9%）显著高于第一三分位组（11.5%）与第二三分位组（13.3%）。经测算，纤维蛋白原与白蛋白比值的最优截断值为10.79，对应的受试者工作特征曲线（receiver-operating characteristic curve, ROC）下面积为0.68。依据该截断值，患者被划分为低FAR组（n=12533，占比67.5%）与高FAR组（n=6029，占比32.5%）。经逆概率加权校正后，高FAR组的1年死亡风险显著高于低FAR组（36.4% vs. 12.4%，校正后风险比=1.72；95%置信区间（confidence interval, CI）：1.59–1.86；P<0.001）。不过，在针对1年死亡预测的受试者工作特征曲线分析中，ICU入院时FAR的曲线下面积（C统计量：0.684，95%CI：0.673–0.694）与同期SOFA评分的曲线下面积（C统计量：0.679，95%CI：0.669–0.688）无显著差异（P=0.532）。研究结论：本研究表明，ICU收治患者入院时的FAR与SOFA评分均与1年死亡率相关。尤为关键的是，FAR相较于SOFA评分，更易在重症患者中获取检测数据。因此，FAR在预测此类患者的长期死亡率方面具备可行性与可靠性。