Supplementary Material for: Association between the triglyceride-glucose index and all-cause mortality in critically ill patients with acute kidney injury

Background: The triglyceride-glucose (TyG) Index is a reliable alternative biomarker of insulin resistance, but the association between the TyG Index and acute kidney injury(AKI) in critically ill patients remains unclear.
Methods: The data for the study was extracted from the Medical Information Mart for Intensive Care IV (MIMIC-IV) database. Cox regression and restricted cubic spline(RCS) analysis were performed to analyze the association between the TyG index and all cause mortality. Besides, cox regression was carried out in subgroups of age, gender, BMI, diabetes history and dialysis status.
Results: A total of 7508 critically ill participants with AKI from the MIMIC-IV database were included in study, with 3688(49.12%) participants failed to survive. In cox regression, after confounder adjustment, patients with a higher TyG Index had a higher risk of all cause mortality (HR = 1.845, 95% CI =1.49-2.285, p <0.001). In RCS, after confounder adjustment, the risk of death was positively correlated with the increased value of the TyG index when TyG index surpassed 10.014. This relationship was validated in age, gender, BMI and diabetes subgroups but not in the dialysis subgroup. Interestingly, RCS analysis demonstrated that, in patients undertaking dialysis, there is a “U” shape curve for the value of TyG index and risk of all cause mortality. When TyG index is less than 10.460, the risk of all cause mortality would decrease with the increase value of TyG index, while when TyG index is higher than 11.180, the risk of all cause mortality would increase firmly with the increase value of TyG index.
Conclusion: Overall, higher TyG index is associated with higher risk of all-cause mortality in critically ill AKI. Interestingly, the relationship in dialysis subgroup follows a "U"-shaped curve, indicating the importance of a properly clinical blood glucose and lipid management of this particular population.

研究背景：甘油三酯-葡萄糖（TyG）指数是评估胰岛素抵抗的可靠替代生物标志物，但目前重症患者中该指数与急性肾损伤（AKI）的关联仍不明确。
研究方法：本研究数据提取自重症医学信息数据库第四版（MIMIC-IV）。采用Cox回归与限制性立方样条（RCS）分析，探究TyG指数与全因死亡率的关联。此外，按年龄、性别、体质量指数（BMI）、糖尿病病史及透析状态开展亚组Cox回归分析。
研究结果：本研究共纳入来自MIMIC-IV数据库的7508例重症AKI患者，其中3688例（49.12%）患者死亡。经混杂因素校正的Cox回归分析显示，TyG指数较高的患者全因死亡风险更高（风险比HR=1.845，95%置信区间95% CI=1.49~2.285，P<0.001）。限制性立方样条分析显示，经混杂因素校正后，当TyG指数超过10.014时，死亡风险随TyG指数升高呈正相关。该关联在年龄、性别、BMI及糖尿病亚组中均得到验证，但在透析亚组中未发现此规律。值得注意的是，限制性立方样条分析显示，在接受透析的患者中，TyG指数与全因死亡风险呈现U型曲线关系：当TyG指数低于10.460时，全因死亡风险随TyG指数升高而降低；而当TyG指数高于11.180时，全因死亡风险则随TyG指数升高持续上升。
研究结论：总体而言，重症AKI患者的TyG指数越高，其全因死亡风险越高。有趣的是，透析亚组中的关联呈现U型曲线，提示对此类特殊人群进行合理的临床血糖与血脂管理具有重要意义。