Learning curve for endoscopic retrograde appendicitis therapy: a multicenter retrospective study with different levels of trainees

Abstract Background and aim Endoscopic retrograde appendicitis therapy (ERAT) is a minimally invasive treatment for appendicitis, widely practiced in China. Clarifying the learning curve, especially among endoscopists with varying endoscopic experience, including endoscopic retrograde cholangiopancreatography (ERCP) skills, is essential for its broader adoption. This study aimed to determine the number of cases required to achieve procedural proficiency across different experience levels, as well as to examine the disparities in technical success rates and clinical outcomes. Methods In this multicenter retrospective study, 655 consecutive patients who had undergone ERAT between October 2021 and March 2024 in The First Affiliated Hospital of Zhengzhou University, Jingxing County Hospital, and The Affiliated Taian City Central Hospital of Qingdao University were analyzed. All ERAT procedures were performed by nine trainees from three hospitals, categorized into novice, non-ERCP experience, and ERCP experience groups. Outcomes included technical/clinical success, procedure time, pain, recurrence, length of stay, and adverse events. Learning curves were evaluated with cumulative sum (CUSUM) based on procedure time. Results Technical and clinical outcomes improved with increasing experience in all groups. Proficiency occurred at the 31st case in the ERCP group, the 55th in the non‑ERCP group, and the 59th in novices. The ERCP group had the highest technical (99.1%) and clinical (94.4%) success (P = 0.023 and P = 0.093), the shortest mean procedure time (20.9 minutes; P 0.001), and the lowest recurrence (P 0.001). Complication rates, including intraoperative and postoperative adverse events, were low and similar across groups (0.8%–2.6%, P 0.05). Postoperative pain and hospital stay decreased with experience (P 0.05). Conclusions Endoscopists with extensive prior endoscopic experience, particularly in ERCP, achieve proficiency in ERAT more rapidly. Structured training programs tailored to different experience levels are essential to support the safe and effective global implementation of ERAT.