Novick R J, Fox S A, Stitt L W, Swinamer S A, Lehnhardt K R, Rayman R, Boyd W D
London Health Sciences Center and University of Western Ontario, Canada.
Ann Thorac Surg. 2001 Sep;72(3):S1016-21. doi: 10.1016/s0003-4975(01)02949-6.
Use of the sequential probability cumulative sum (CUSUM) technique may be more sensitive than standard statistical analyses in detecting a cluster of surgical failures. We applied CUSUM methods to evaluate the learning curve after a policy change by a single surgeon from routine on-pump (cardiopulmonary bypass [CPB]) to off-pump coronary artery bypass grafting (OPCAB).
Fifty-five consecutive first-time coronary artery bypass patients (CPB group) were compared with the next 55 patients undergoing an attempt at routine OPCAB using the same coronary stabilizer. The goal in OPCAB patients was to obtain complete revascularization, albeit with a low threshold for conversion to CPB to maximize patient safety during the learning curve. Preoperative patient risk was calculated using previously validated models of the Cardiac Care Network of Ontario. The occurrence of operative mortality and nine predefined major complications (myocardial infarction, bleeding, stroke, renal failure, balloon pump use, mediastinitis, respiratory failure, life-threatening arrhythmia, and sepsis) was compared between the CPB and OPCAB groups using Wilcoxon, Fisher exact, and two-tailed t tests, as well as CUSUM methodology. An intention to treat analysis was performed.
The CPB and OPCAB groups had similar predicted mortality and length of stays (2.2% +/- 2.5%, 8.1 +/- 2.5 days versus 2.4% +/- 3.5%, 8.1 +/- 2.4 days, respectively). The mean number of grafts per patient was 3.1 +/- 0.7 in the CPB group versus 3.0 +/- 0.7 in the OPCAB group (p = 0.45). Two of 55 (3.6%) CPB patients died, as opposed to 1 of 55 (1.8%) OPCAB patients (p = 0.99). Eight of 55 CPB patients (14.5%) incurred major complications, as opposed to 4 of 55 (7.3%) OPCAB patients (p = 0.36). Median hospital length of stay was 6.0 days in the CPB group versus 5.0 days in the OPCAB group (p = 0.28). On CUSUM analysis, the failure curve in CPB patients approached the upper 80% alert line after eight cases, whereas the curve in OPCAB patients reached below the lower 80% (reassurance) boundary 28 cases after the policy change, indicating superior results in the OPCAB group despite the learning curve.
A policy change from coronary artery bypass on CPB to routinely attempting OPCAB can be accomplished safely despite the learning curve. CUSUM analysis was more sensitive than standard statistical methods in detecting a cluster of surgical failures and successes.
在检测手术失败聚集情况时，序贯概率累积和（CUSUM）技术可能比标准统计分析更敏感。我们应用CUSUM方法评估了一名外科医生从常规体外循环（心肺转流[CPB]）冠状动脉搭桥术改为非体外循环冠状动脉搭桥术（OPCAB）后的学习曲线。
将55例连续的首次冠状动脉搭桥患者（CPB组）与接下来55例使用相同冠状动脉固定器尝试进行常规OPCAB的患者进行比较。OPCAB患者的目标是实现完全血运重建，尽管在学习曲线期间转换为CPB的阈值较低，以最大限度提高患者安全性。使用安大略省心脏护理网络先前验证的模型计算术前患者风险。使用Wilcoxon检验、Fisher精确检验、双尾t检验以及CUSUM方法比较CPB组和OPCAB组手术死亡率和九种预先定义的主要并发症（心肌梗死、出血、中风、肾衰竭、使用球囊泵、纵隔炎、呼吸衰竭、危及生命的心律失常和败血症）的发生情况。进行意向性治疗分析。
CPB组和OPCAB组的预测死亡率和住院时间相似（分别为2.2%±2.5%，8.1±2.5天和2.4%±3.5%，8.1±2.4天）。CPB组患者平均移植血管数为3.1±0.7，而OPCAB组为3.0±0.7（p = 0.45）。55例CPB患者中有2例（3.6%）死亡，而55例OPCAB患者中有1例（1.8%）死亡（p = 0.99）。55例CPB患者中有8例（14.5%）发生主要并发症，而55例OPCAB患者中有4例（7.3%）发生主要并发症（p = 0.36）。CPB组中位住院时间为6.0天，OPCAB组为5.0天（p = 0.28）。在CUSUM分析中，CPB患者的失败曲线在8例病例后接近上80%警戒值线，而OPCAB患者的曲线在政策改变后28例病例后低于下80%（安心）边界，表明尽管存在学习曲线，OPCAB组的结果更好。
尽管存在学习曲线，但从CPB冠状动脉搭桥术改为常规尝试OPCAB的政策改变可以安全完成。在检测手术失败和成功聚集情况时，CUSUM分析比标准统计方法更敏感。
