A cumulative sum (CUSUM) analysis studying operative times and complications for a surgeon transitioning from laparoscopic to robot-assisted pediatric pyeloplasty: Defining proficiency and competency.

ABSTRACT

INTRODUCTION: The transition from laparoscopic to robot-assisted procedures leads to potential increase in operative times and health care costs. Cumulative sum (CUSUM) analysis can objectively study the learning curve to detect significant changes in operative timing and monitor complication rates. OBJECTIVE: The objective of this study is to investigate the total and step-specific times for pediatric robot-assisted pyeloplasty (RAP) to investigate the learning curve of a single surgeon transitioning from laparoscopic to RAP. STUDY DESIGN: This prospective cohort study included 50 consecutive RAP procedures performed since the inception of our robotic program from June 2013 to January 2019. The CUSUM of RAP total operative time (OT) was calculated to determine the breakpoints between learning phases using piecewise linear regression. Cumulative-observed-minus-expected failure chart with 80% and 95% reassurance boundary lines was constructed using 5% acceptable and 10% unacceptable complication rates. Step-specific operative times were prospectively recorded by an independent observer for port placement, dissection and hitch stitch placement, pelvis dismemberment and spatulation, suturing and port removal. RESULTS: Piecewise linear regression for OT identified breakpoints at case 13 and 29 suggesting transition at these points between Learning to Proficiency, and Proficiency to Competency. The overall mean OT was 142.2 ± 46.0 min. There was a significant difference in the mean OT between Learning (203.9 ± 35.3 min, the initial 13 cases), Proficiency (159.2 ± 18.6 min, the middle 16 cases), and Competency (126.6 ± 19.7 min, the last 21 cases) phases (p < 0.001). The complication rate for RAP stabilized around the acceptable level of 5% up to case 41 before finalizing at 8% overall. The step-specific analysis suggested that suturing entered the Competency phase at case 27, with a 50% decrease in suturing time from Learning to Proficiency and Competency. DISCUSSION: Our study suggests that by case 30 a surgeon transitioning to RAP can achieve a significant decrease in OT. Complication rates remained within acceptable limits throughout, indicating that RAP can be safely adopted, even in low volume RAP centres. Suturing competency seems to be a significant advantage of the robotic platform as suggested by early significant decrease in suturing times noted between the Learning and Proficiency phases. CONCLUSION: Future studies can confirm these findings and establish reference operative times to aid surgeons and trainees transitioning from laparoscopic pyeloplasty to RAP. Moreover, total OT decreases significantly and relatively soon after transition to RAP.