Learning curve analysis using the cumulative summation method for totally extraperitoneal repair of the inguinal hernia

Purpose The totally extraperitoneal repair (TEP) technique has been widely performed, and compared with open surgery, TEP results in less postoperative pain and similar surgical outcomes in the treatment of inguinal hernias. However, TEP has a longer learning curve than does conventional surgery. Methods The data for patients who underwent TEP for inguinal hernias by a single surgeon between April 2017 and July 2019 were analyzed retrospectively. The cumulative summation (CUSUM) method and the following two variables were used to analyze the learning curve: (1) the operation event (OE), including intraoperative complications and conversion to open surgery; and (2) the operation score (OS), as calculated by the operation time, patient body mass index, and disease characteristics. Results The CUSUM chart showed three phases for both the OE and OS. The former reached a first inflection point after the 85th case and decreased after the 200th case, and the latter reached a plateau after the 101st case and decreased after the 203rd case. The operation time was longer in phases 1 and 2 than in phase 3 (64.2 min versus 47.9 min versus 31.1 min; p < 0.001), and the OS was lower in phase 3 than in the other phases (71.9 points versus 106.4 points versus 142.7 points; p < 0.001). Ten cases of intraoperative complications were observed, all in the first and second phases ( p = 0.011). Conclusion At least approximately 100 cases are required for the initial learning period, and an additional 103 cases are required for the accumulation of additional experience. Surgical competency can be gained after 203 TEPs are performed.