Effect of IWATE laparoscopic difficulty score on postoperative outcomes and costs for robotic hepatectomy: Are complex resections more expensive?

Background: The IWATE criteria, a four-level classification system for laparoscopic hepatectomy, measures technical complexity but lacks studies on its impact on outcomes and costs, especially in robotic surgeries. This study evaluated the effects of technical complexity on perioperative outcomes and costs in robotic hepatectomy.
Methods: Since 2013, we prospectively followed 500 patients who underwent robotic hepatectomy. Patients were classified into four levels of IWATE scores; (low [0-3], intermediate [4-6], advanced [7-9], and expert [10-12]) determined by tumor characteristics, liver function and resection extent. Perioperative variables were analyzed with significance accepted at a p-value ≤.05.
Results: Among 500 patients, 337 (67%) underwent advanced to expert-level operations. Median operative duration was 213 min (range: 16-817 min; mean ± SD: 240 ± 116.1 min; p < .001) and estimated blood loss (EBL) was 95 mL (range: 0-3500 mL; mean ± SD:142 ± 171.1 mL; p < .001). Both operative duration and EBL showed positive correlations with increasing IWATE scores. Median length of stay (LOS) of 3 days (range: 0-34; mean ± SD:4 ± 3.0 days; p < .001) significantly correlated with IWATE score. Total cost of $25 388 (range: $84-354 407; mean ± SD: 29752 ± 20106.8; p < .001) also significantly correlated with operative complexity, however hospital reimbursement did not. No correlation was found between IWATE score and postoperative complications or mortality.
Conclusions: Clinical variables such as operative duration, EBL, and LOS correlate with IWATE difficulty scores in robotic hepatectomy. Financial metrics such as costs but not reimbursement received by the hospital correlate with IWATE scores.
(© 2024 Japanese Society of Hepato‐Biliary‐Pancreatic Surgery.)