Novick Richard J, Fox Stephanie A, Stitt Larry W, Kiaii Bob B, Abu-Khudair Walid, Lee Alex, Benmusa Anas, Swinamer Stuart A, Rayman Reiza, Menkis Alan H, McKenzie F Neil, Quantz Mackenzie A, Boyd W Douglas
Division of Cardiac Surgery, London Health Sciences Center, London, Ontario, Canada.
J Card Surg. 2002 Nov-Dec;17(6):520-8. doi: 10.1046/j.1540-8191.2002.01008.x.
We have shown that cumulative sum (CUSUM) failure analysis may be more sensitive than standard statistical methods in detecting a cluster of adverse patient outcomes after cardiac surgical procedures. We therefore applied CUSUM, as well as standard statistical techniques, to analyze a surgeon's experience with off-pump coronary artery bypass grafting (OPCAB) and on-pump procedures to determine whether the two techniques have similar or different outcomes.
In 320 patients undergoing nonemergent, first time coronary artery bypass grafting, preoperative patient characteristics, rates of mortality and major complications, and ICU and hospital lengths of stay were compared between the on-pump and OPCAB cohorts using Fisher's exact tests and Wilcoxon two sample tests. Predicted mortality and length of stay were determined using previously validated models of the Cardiac Care Network of Ontario. Observed versus expected ratios of both variables were calculated for the two types of procedures. Furthermore, CUSUM curves were constructed for the on-pump and OPCAB cohorts. A multivariable analysis of the predictors of hospital length of stay was also performed to determine whether the type of coronary artery bypass procedure had an independent impact on this variable.
The predicted mortality risk and predicted hospital length of stay were almost identical in the 208 on-pump patients (2.2 +/- 3.9%; 8.2 +/- 2.5 days) and the 112 OPCAB patients (2.0 +/- 2.2%; 7.8 +/- 2.1 days). The incidence of hospital mortality and postoperative stroke were 2.9% and 2.4% in on-pump patients versus zero in OPCAB patients (p = 0.09 and 0.17, respectively). Mechanical ventilation for greater than 48 hours was significantly less common in OPCAB (1.8%) than in on-pump patients (7.7%, p = 0.04). The rate of 10 major complications was 14.9% in on-pump versus 8.0% in OPCAB patients (p = 0.08). OPCAB patients experienced a hospital length of stay that was a median of 1.0 day shorter than on-pump patients (p = 0.01). The observed versus expected ratio for length of stay was 0.78 in OPCAB patients versus 0.95 in on-pump patients. On CUSUM analysis, the failure curve in OPCAB patients was negative and was flatter than that of on-pump patients throughout the duration of the study. Furthermore, OPCAB was an independent predictor of a reduced hospital length of stay on multivariable analysis.
OPCAB was associated with better outcomes than on-pump coronary artery bypass despite a similar predicted risk. This robust finding was documented on sensitive CUSUM analysis, using standard statistical techniques and on a multivariable analysis of the independent predictors of hospital length of stay.
我们已经表明，累积和（CUSUM）失效分析在检测心脏外科手术后不良患者结局的聚集方面可能比标准统计方法更敏感。因此，我们应用CUSUM以及标准统计技术来分析外科医生进行非体外循环冠状动脉搭桥术（OPCAB）和体外循环手术的经验，以确定这两种技术的结局是否相似或不同。
在320例接受非急诊首次冠状动脉搭桥术的患者中，使用Fisher精确检验和Wilcoxon两样本检验比较体外循环组和OPCAB组的术前患者特征、死亡率和主要并发症发生率以及重症监护病房（ICU）和住院时间。使用安大略省心脏护理网络先前验证的模型确定预测死亡率和住院时间。计算两种手术类型这两个变量的观察值与期望值之比。此外，为体外循环组和OPCAB组构建CUSUM曲线。还对住院时间的预测因素进行了多变量分析，以确定冠状动脉搭桥手术类型是否对该变量有独立影响。
208例体外循环患者（2.2±3.9%；8.2±2.5天）和112例OPCAB患者（2.0±2.2%；7.8±2.1天）的预测死亡风险和预测住院时间几乎相同。体外循环患者的医院死亡率和术后中风发生率分别为2.9%和2.4%，而OPCAB患者为零（p分别为0.09和0.17）。OPCAB患者中机械通气超过48小时的情况明显少于体外循环患者（1.8%对7.7%，p = 0.04）。体外循环患者的10种主要并发症发生率为14.9%，而OPCAB患者为8.0%（p = 0.08）。OPCAB患者的住院时间中位数比体外循环患者短1.0天（p = 0.01）。OPCAB患者住院时间的观察值与期望值之比为0.78，而体外循环患者为0.95。在CUSUM分析中，OPCAB患者的失效曲线为负，并且在整个研究期间比体外循环患者的曲线更平缓。此外，在多变量分析中，OPCAB是住院时间缩短的独立预测因素。
尽管预测风险相似，但OPCAB比体外循环冠状动脉搭桥术的结局更好。这一有力发现通过敏感的CUSUM分析、使用标准统计技术以及对住院时间独立预测因素的多变量分析得到了证实。
