The Japanese Difficulty Scoring System Correlates with Postoperative Outcome Assessed by the Comprehensive Complication Index in Patients Undergoing Minimally Invasive Liver Resection

Introduction: The Japanese difficulty score (JDS) was developed to standardize the difficulty grading of laparoscopic hepatectomy. The JDS has not consistently correlated well with postoperative outcomes such as Clavien-Dindo complications. This study aims to determine if the JDS correlates with complications as classified by the more inclusive comprehensive complication index (CCI). Methods: A single institutional database was retrospectively queried for all purely minimally-invasive (MIS) hepatectomies performed between January 2008 and December 2019Patient charts were reviewed and data was collected. Patients were grouped into “Low” (<4), “Intermediate” (4-6), and “High” (7+) difficulty based on JDS. Complications were graded using CCI. Statistical comparisons were made using ANOVA or χ2 test, as appropriate. IRB approval was obtained. Results: 413 pure MIS resections were performed. There were 75 (18.2%) Low, 207 (50.1%) Intermediate, and 131 (31.7%) High difficulty MIS hepatectomies. There were no demographic differences. High difficulty was associated with longer operative time (p<0.001), higher mean EBL (p<0.001), and were more likely to require blood transfusion (p<0.001). Mean length of stay (LOS) was longer for more difficult resections (p<0.001). There was no difference between groups in Clavien-Dindo complications or 30-day readmissions. The CCI was significantly higher (Low 7.0, Intermediate 9.5, High 15.8; p=0.006) for more difficult resections. Post-hepatectomy liver failure (PHLF) occurred more frequently with higher JDS (p=0.0023). Conclusions: MIS liver resections with higher JDS were associated with increased operative times, EBL, blood transfusions, LOS, PHLF and overall complications as indicated by the CCI, despite no difference between groups in Clavien-Dindo complications.