Graduated Autonomy of Laparoscopic Liver Resection Based on Liver Resection Complexity: A Western and Eastern Bi-Institution Study for Learning Curve

Introduction: Laparoscopic liver resection (LLR) requires a high degree of expertise in both hepatobiliary and minimally invasive surgery. Our group previously reported a 3-level LLR complexity classification based on intra-postoperative outcomes: grade I (low), grade II (intermediate), and grade III (high). We evaluated the learning curve effect in each complexity grade to assess the experience needed for a surgeon to safely progress through the grades. Materials and Method Patients who underwent LLR during 1994–2020 at the Institut Mutualiste Montsouris (IMM) and The University of Tokyo (UT) during 2008–2023 were included in the study. The learning curve for operating time was evaluated using the standardized (CUSUM) analysis for each complexity grade. Results: A total of 503 patients (grade I, 198; grade II, 87; grade III, 218) at the IMM and 221 patients (grade I, 135; grade II, 57; grade III, 29) at the UT met the inclusion criteria. The CUSUM analysis showed that the deviation of operating time was found up to 40 cases for grade I resections, 30 cases for grade II resections, and 50 cases for grade III resections. By dividing cohorts based on these numbers for each group and each institution and labeling these cases as the pre-learning groups and the remaining as the post-learning group, surgical outcomes and postoperative complications were generally improved in the post-learning groups in both institutions. Conclusions: A gradual progression in LLR per complexity grade as follow: 40 cases of low grade I procedures before starting intermediate complexity grade II procedures, and 30 cases of intermediate complexity grade II procedures before starting high complexity grade III procedures may ensure a safe implementation of high complexity LLR procedures.