Validity of the Institut Mutualiste Montsouris classification system for robotic liver resection.

BACKGROUND: The Institut Mutualiste Montsouris (IMM) classification system is one of several widely accepted difficulty scoring systems for laparoscopic liver resections. Nothing is yet known about the applicability of this system for robotic liver resections. METHODS: We conducted a retrospective review of 359 patients undergoing robotic hepatectomies between 2016 and 2022. Resections were classified into low, intermediate, and high difficulty level. Data were analyzed utilizing ANOVA of repeated measures, 3 x 2 contingency tables, and area under the receiving operating characteristic (AUROC) curves. Data are presented as median (mean ± SD). RESULTS: Of the 359 patients, 117 were classified as low-difficulty level, 92 as intermediate, and 150 as high. The IMM system correlates well with tumor size (p = 0.002). The IMM system was a strong predictor of intraoperative outcomes including operative duration (p<0.001) and estimated blood loss (EBL) (p<0.001). The IMM system also showed a strong calibration for predicting an open conversion (AUC=0.705) and intraoperative complications (AUC=0.79). In contrast, the IMM system was a poor predictor of postoperative complications, mortality, and readmission. CONCLUSION: The IMM system provides a strong correlation with intraoperative, but not postoperative outcomes. A dedicated difficulty scoring system should be developed for robotic hepatectomy.

Analysis of Clinical Outcomes After Robotic Hepatectomy Applying the Western-Model Southampton Laparoscopic Difficulty Scoring System. An Experience From a Tertiary US Hepatobiliary Center.

BACKGROUND: Identification of resections with high risk of intraoperative complications is critical in guiding case selection for minimally invasive liver surgery. Several Japanese and European difficulty scoring systems have been proposed for laparoscopic liver surgery. However, the applicability of these systems for robotic liver resections has not been fully investigated. This study considers the Southampton system and examines its validity when applied to robotic hepatectomies. METHODS: We undertook a retrospective review of 372 patients who underwent robotic hepatectomies for various indications between 2013 and 2022. Of these patients, 63 operations were classified as low risk, 91 as moderate risk, 198 as high risk and 20 as extremely high risk based on Southampton criteria. Patient outcomes were compared by utilizing an ANOVA of repeated measures. Data are presented as median (mean ± SD). RESULTS: The Southampton difficulty scoring system was a strong predictor of intraoperative variables including tumor size, operative duration, estimated blood loss (EBL), and incidence of major vs minor resection (all P < .0001). In contrast, the Southampton system was a weaker predictor of postoperative outcomes including 30-day mortality (P = .15), length of stay (P = .13), and readmissions within 30 days (P = .38). CONCLUSION: The Southampton difficulty scoring system is a valid system for classifying robotic liver resections and is a strong predictor of intraoperative outcomes. However, the system was found to be a weaker predictor of postoperative outcomes. This finding may suggest the need for proposal of a new difficulty scoring system for robotic hepatectomies.