Utility of the Iwate Difficulty Scoring System for the Stratification of Laparoscopic Right Hepatectomies: An International Multicenter Study

Background: Laparoscopic right hepatectomy (L-RH) is a technically complex procedure, characterized by diverse tumor presentations and anatomical variations. While the Iwate Difficulty Scoring System (I-DSS) is widely utilized to assess technical difficulty in laparoscopic liver resections, its predictive value for surgical outcomes in L-RH remains unclear. This study aimed to evaluate the clinical utility of the I-DSS specifically in the context of L-RH. Methods: This international, multicenter study included 1732 patients who underwent L-RH at 78 centers between 2005 and 2023. Baseline clinicopathological characteristics and surgical outcomes were collected and analyzed based on I-DSS grades. Multivariable analyses were performed to adjust for potential confounders. Results: Patients were categorized into three I-DSS grades: intermediate (n = 13), advanced (n = 355), and expert (n = 1364). Unadjusted analysis showed that higher I-DSS grades were associated with shorter operation time and increased morbidity. However, after adjustment for baseline factors, no significant differences were observed across I-DSS grades in terms of intra- and postoperative outcomes, including operation time, blood loss, transfusion, morbidity, mortality, and surgical margin positivity. Conclusions: The I-DSS has limited ability to stratify technical difficulty in L-RH. Future studies should be undertaken to develop a new difficulty classification system tailored specifically to specific procedures such as L-RH.