Serum anion gap at admission predicts all-cause mortality in critically ill patients with cerebral infarction: evidence from the MIMIC-III database

Recent studies reported that serum anion gap could be regarded as a prognostic biomarker for patients admitted to intensive care units. However, the association between AG and mortality in cerebral infarction patients remained largely unknown.
Relevant clinical data were collected from Medical Information Mart for Intensive Care III. Patients were divided into three groups according to tertiles of AG. Kaplan–Meier curve and Cox proportional hazards models were used to evaluate the association between AG levels and all-cause mortality. Subgroup analyses were performed to verify the predictive role of AG on mortality.
Kaplan–Meier analysis showed that patients with higher AG had shorter survival time. Cox regression model indicated high AG as an independent risk factor of 30-day, 60-day and 180-day all-cause mortality (30-day: HR = 2.45, 95% CI = 1.21–4.97, 60-day: HR = 2.04, 95% CI = 1.07–3.89, and 180-day: HR = 1.85, 95% CI = 1.02–3.36). However, no significance was observed between AG and 365-day all-cause mortality (HR = 1.56, 95% CI = 0.87–2.78).
High AG was associated with increased risk of all-cause mortality, and AG could be an independent short-term prognostic factor for cerebral infarction.

近期已有研究表明，血清阴离子间隙（serum anion gap, AG）可作为重症加强护理病房（intensive care units, ICU）收治患者的预后生物标志物。然而，AG与脑梗死患者死亡率之间的关联目前仍未得到充分阐明。
本研究从重症医学信息数据库第三版（Medical Information Mart for Intensive Care III, MIMIC-III）中提取相关临床数据，依据AG的三分位数将患者划分为三组。采用Kaplan–Meier曲线与Cox比例风险模型，评估AG水平与全因死亡率之间的关联，并通过亚组分析验证AG对死亡率的预测价值。
Kaplan–Meier分析结果显示，AG水平较高的患者生存时长更短。Cox回归分析表明，高AG是30天、60天及180天全因死亡率的独立危险因素（30天：HR=2.45，95%CI=1.21~4.97；60天：HR=2.04，95%CI=1.07~3.89；180天：HR=1.85，95%CI=1.02~3.36）。但AG与365天全因死亡率之间未观察到显著关联（HR=1.56，95%CI=0.87~2.78）。
高AG水平与全因死亡率风险升高相关，AG可作为脑梗死患者的独立短期预后因素。