Related Experiment Videos
The learning curve of an academic cardiac surgeon: use of the CUSUM method
1Division of Cardiovascular Surgery, The London Health Sciences Centre, Ontario, Canada. rjnovick@julian.uwo.ca
Insights
This study analyzed a cardiac surgeon's learning curve over 10 years, finding significant improvements in coronary artery bypass grafting mortality and select morbidities. The cumulative sum (CUSUM) method identified early practice challenges, supporting mentorship for new surgeons.
Area of Science:
- Cardiac Surgery Outcomes Research
- Surgical Learning Curve Analysis
- Quality Improvement in Healthcare
Background:
- Limited research exists on individual cardiac surgeon learning curves and their impact on patient outcomes.
- Understanding surgeon learning curves is crucial for optimizing patient safety and surgical performance.
- This study addresses the need to statistically analyze a surgeon's learning curve in cardiac operations.
Purpose of the Study:
- To statistically analyze the learning curve of an academic cardiac surgeon over a 10-year period.
- To assess the impact of the learning curve on operative morbidity and mortality rates.
- To evaluate the utility of the cumulative sum (CUSUM) method for quality control in cardiac surgery.
Main Methods:
- Analysis of 1347 consecutive cardiac surgical patients from October 1988 to September 1998.
- Patients grouped into five 2-year blocks; outcomes measured by mortality, myocardial infarction, stroke, and other complications.
- Statistical comparison using chi-square and ANOVA; CUSUM method applied to identify performance trends.
Main Results:
- Overall operative mortality and most morbidities showed no significant change, except for increased patient age.
- Significant linear decreases observed in coronary artery bypass grafting (CABG) mortality, perioperative myocardial infarction, intra-aortic balloon pump use, and reoperation for bleeding.
- CUSUM analysis indicated suboptimal results in the first year, with improved performance in later years, demonstrating the method's sensitivity.
Conclusions:
- Coronary artery bypass grafting mortality and select perioperative morbidity rates improved linearly with surgeon experience.
- The CUSUM method effectively identified early practice performance issues and shows promise for prospective quality control.
- Mentorship for new cardiac surgeons during their initial years of independent practice is supported by these findings.
Background:
Despite the sizeable volume of research on the determinants of outcome after cardiac operations, few articles have analyzed the learning curves of individual cardiac surgeons over time. The objective of our study was to analyze statistically the learning curve of an academic cardiac surgeon in reducing operative morbidity and mortality during a 10-year interval.
Methods:
The study cohort of 1347 consecutive and unselected patients undergoing cardiac surgical operations from October 1988 to September 1998 were grouped into five 2-year blocks (periods 1 to 5) according to the date of operation. The main outcome measures were operative mortality rate and standardized definitions of perioperative myocardial infarction, intra-aortic balloon pump use, reoperation for bleeding, stroke, sternal wound complications, sepsis, and respiratory insufficiency. Preoperative risk factors and operative results in periods 1 to 5 were compared statistically using a chi-square test for linear trend (categorical variables) or analysis of variance with linear contrast and lack of fit tests (continuous variables). In addition, the cumulative sum (CUSUM) method was used to determine the association among operative morbidity, mortality, and prespecified 80% alert and 95% alarm boundary lines in practice years 1, 5, and 9.
Results:
Of the preoperative risk factors, only patient age showed an important change during the 10 years of the study (61.3+/-0.7 to 64.3+/-0.6, p = 0.001). There were no statistically significant changes from periods 1 to 5 in overall operative mortality (4.0% to 2.2%, p = 0.56) or in the rates of perioperative stroke (1.8% to 3.8%, p = 0.33), sternal wound complications (0.4% to 0.8%, p = 0.97), sepsis (0.9% to 0.8%, p = 0.63), or respiratory failure (4.4% to 2.8%, p = 0.21). Decreases occurred in a linear fashion during periods 1 to 5 in mortality after coronary artery bypass grafting (5.1% to 1.3%, p = 0.012) and in the rates of perioperative myocardial infarction (7.0% to 2.2%, p = 0.005), intra-aortic balloon pump use (7.0% to 3.0%, p = 0.05), and reoperation for bleeding (8.4% to 2.2%, p = 0.001). The number of uneventful cases between a death or complication increased from 2.82+/-0.43 in period 1 to 6.44+/-1.10 in period 5 (p < 0.001). On CUSUM analysis, the cumulative failure rate in year 1 transgressed the upper 80% alert line after 56 cases and the upper 95% alarm line after 69 cases. During years 5 and 9 the failure rate gravitated around the 80% and 95% "reassurance" lines, respectively, indicating improved results as compared to year 1.
Conclusions:
The mortality rate after coronary artery bypass grafting and select perioperative morbidity rates improved in a linear fashion from the onset of independent practice to year 10. The CUSUM method was helpful in identifying suboptimal results during the first year of practice and shows promise as a method of prospective quality control in cardiac surgery. These data support mentorship of new consultants by a senior surgeon during the first year or two of independent practice.