Supplementary Material for: Developing and validating a simple risk score for patients with acute myocardial infarction

Introduction: Mortality from acute myocardial infarction (AMI) remains substantial. The current study is aimed at developing a novel simple risk score for AMI.
Methods: The Coronary Artery Tree description and Lesion EvaluaTion (CatLet) extended validation trial (ChiCTR2000033730) and the CatLet validation trial (ChiCTR-POC-17013536), both being registered with chictr.org, served as the derivation and validation datasets, respectively. Both datasets included 1018 and 308 patients, respectively. They all suffered from AMI and underwent percutaneous intervention (PCI). The endpoint was 4-year all-cause death. Lasso regression analysis was used for covariate selection and coefficient estimation.
Results: Of 26 candidate predictor variables, four strongest predictors for 4-year mortality were included in this novel risk score with an acronym of BACEF (serum alBumin, Age, serum Creatinine, and LVEF). This score was well calibrated and yielded an AUC (95%CI) statistics of 0.84(0.80-0.87) in internal validation, 0.89(0.83-0.95) in internal-external (temporal) validation, and 0.83(0.77-0.89) in external validation. Notably, it outperformed the ACEF, ACEFII, GRACE scores with respect to 4-year mortality prediction.
Conclusion: A simple risk score for 4-year mortality risk stratification was developed, extensively validated, and calibrated in patients with AMI. This novel BACEF score may be a useful risk stratification tool for patients with AMI.

引言：急性心肌梗死（acute myocardial infarction, AMI）的死亡率仍处于较高水平。本研究旨在开发一款针对AMI的新型简易风险评分模型。
方法：冠状动脉树描述与病变评估（Coronary Artery Tree description and Lesion EvaluaTion, CatLet）扩展验证试验（ChiCTR2000033730）与CatLet验证试验（ChiCTR-POC-17013536）均在中国临床试验注册中心（chictr.org）完成注册，分别作为模型推导数据集与验证数据集。两个数据集分别纳入1018例与308例AMI患者，所有受试者均确诊为AMI并接受经皮介入治疗（percutaneous intervention, PCI）。研究终点为4年全因死亡。采用Lasso回归分析进行协变量筛选与系数估计。
结果：本研究从26个候选预测变量中筛选出4个对4年死亡率预测效能最强的指标，构建了缩写为BACEF的新型风险评分模型，其组成指标包括血清白蛋白、年龄、血清肌酐以及左心室射血分数（Left Ventricular Ejection Fraction, LVEF）。该评分模型校准性能良好，内部验证的受试者工作特征曲线下面积（AUC，95%置信区间）为0.84（95%CI：0.80~0.87），内外部（时间序列）验证的AUC为0.89（95%CI：0.83~0.95），外部验证的AUC为0.83（95%CI：0.77~0.89）。值得注意的是，相较于ACEF、ACEFII及GRACE评分模型，该评分在4年全因死亡预测中表现更优。
结论：本研究针对AMI患者开发了一款用于4年死亡率风险分层的简易风险评分模型，并完成了多维度验证与校准。这款新型BACEF评分可作为AMI患者临床风险分层的有效工具。