Probabilistic Model for Prediction of Prognostics in Myocardial Revascularization: Complications in Coronary Surgery

Abstract Introduction: Risk scores evaluate pre-operatory risk and present support for clinical decisions, however the performance of these tools in samples different from the original ones remains unclear. Objectives: Investigate the external validity of risk scores (STS and Euroscore) in cardiac surgery and the predictive performance of clinical features derived from the sample. Methods: Retrospective Cohort study conducted between October, 2010, and April, 2015. We used logistic regression to identify risk factors for hospital morbidity. The sample was divided for cross-validation, with 2/3 of the patients selected for model fitting and 1/3 for prediction testing. The performance of risk scores and clinical features was evaluated through AUROC and calibraton the Hosmer-Lemeshow test (H-L). Results: Data was retrieved from 472 patients who underwent coronary cardiac surgery in Hospital Santa Izabel da Santa Casa, BA. Mean age was 62.8 years old and 32.5% of the sample were women. Traditional surgical risk scores did not present significant discriminative performance for this sample. Factors associated with the outcome after adjusting for covariates were: age, previous myocardial revascularization and pre-surgical creatinine levels. The adjusted model presented similar discrimination and calibration values during training (AUROC = 0,72; IC 95% 0,59-0,84; H-L valor p: 0,41) and validation (AUROC = 0,70; IC 95% 0,55 - 0,84; H-L valor p: 0,197). Conclusion: Traditional scores may be inaccurate when applied to different environments. New risk scores with good predictive power can be developed using local clinical variables.

摘要 引言：风险评分用于评估术前风险并为临床决策提供支持，但此类工具在不同于原始研究的样本中的应用表现仍不明确。研究目的：探究心脏手术中胸外科医师学会风险评分（STS）及欧洲心脏手术风险评分（Euroscore）的外部有效性，以及本研究样本衍生的临床特征的预测性能。研究方法：本研究为回顾性队列研究，实施时间为2010年10月至2015年4月。采用逻辑回归分析识别院内并发症的危险因素。将样本划分为两部分以进行交叉验证：2/3的患者用于模型拟合，剩余1/3用于预测测试。通过受试者工作特征曲线下面积（AUROC）及Hosmer-Lemeshow（H-L）校准检验，评估风险评分与临床特征的模型性能。研究结果：从巴西巴伊亚州圣之家圣伊莎贝尔医院接受冠状动脉心脏手术的472例患者中获取数据。受试者平均年龄为62.8岁，女性占比32.5%。传统手术风险评分在本样本中未表现出显著的区分性能。经协变量校正后，与研究结局相关的危险因素包括：年龄、既往心肌血运重建史及术前肌酐水平。校正后的模型在训练集与验证集中均表现出相近的区分度与校准度：训练集AUROC=0.72，95%置信区间（CI）0.59~0.84，H-L检验P值=0.41；验证集AUROC=0.70，95%CI 0.55~0.84，H-L检验P值=0.197。研究结论：传统风险评分应用于不同医疗环境时可能存在准确性不足的问题。可利用本地临床变量开发具备良好预测能力的新型风险评分。