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Multicenter Study
. 2025 Jun;51(6):109597.
doi: 10.1016/j.ejso.2025.109597. Epub 2025 Jan 24.

Validation of the Iwate scoring system for the stratification of laparoscopic liver resections: An international multicenter study

Yufu Peng  1 , Fei Liu  1 , Bo Li  1 , Yonggang Wei  2 , Hwee-Leong Tan  3 , Nicholas L Syn  4 , David Fuks  5 , Olivier Soubrane  5 , Safi Dokmak  6 , Salvatore Gruttadauria  7 , Giuseppe Zimmitti  8 , Bashar Jaber  8 , Federica Cipriani  9 , Yutaro Kato  10 , Olivier Scatton  11 , Paulo Herman  12 , Davit L Aghayan  13 , Marco V Marino  14 , Roland S Croner  15 , Vincenzo Mazzaferro  16 , Adrian K H Chiow  17 , Iswanto Sucandy  18 , Arpad Ivanecz  19 , Sung Hoon Choi  20 , Jae Hoon Lee  21 , Mikel Prieto  22 , Marco Vivarelli  23 , Felice Giuliante  24 , Andrea Ruzzenente  25 , Chee-Chien Yong  26 , Mengqiu Yin  27 , Constantino Fondevila  28 , Mikhail Efanov  29 , Zenichi Morise  30 , Fabrizio Di Benedetto  31 , Raffaele Brustia  32 , Raffaele Dalla Valle  33 , Ugo Boggi  34 , David Geller  35 , Andrea Belli  36 , Riccardo Memeo  37 , Alejandro Mejia  38 , James O Park  39 , Fernando Rotellar  40 , Gi-Hong Choi  41 , Ricardo Robles-Campos  42 , Kiyoshi Hasegawa  43 , Xiaoying Wang  44 , Robert P Sutcliffe  45 , Johann Pratschke  46 , Eric C H Lai  47 , Charing C N Chong  48 , Mathieu D'Hondt  49 , Kazuteru Monden  50 , Santiago Lopez-Ben  51 , T Peter Kingham  52 , Rong Liu  53 , Alessandro Ferrero  54 , Giuseppe Maria Ettorre  55 , Daniel Cherqui  56 , Xiao Liang  57 , Kohei Mishima  58 , Go Wakabayashi  58 , Roberto I Troisi  59 , Tan-To Cheung  60 , Motokazu Sugimoto  61 , Atsushi Sugioka  10 , Ho-Seong Han  62 , Tran Cong Duy Long  63 , Mohammad Abu Hilal  64 , Wanguang Zhang  65 , Kuo-Hsin Chen  66 , Luca Aldrighetti  9 , Bjorn Edwin  13 , Brian K P Goh  67 ; International robotic and laparoscopic liver resection study group investigators
Collaborators, Affiliations
Multicenter Study

Validation of the Iwate scoring system for the stratification of laparoscopic liver resections: An international multicenter study

Yufu Peng et al. Eur J Surg Oncol. 2025 Jun.

Abstract

Introduction: The Iwate difficulty scoring system (DSS) is one of the most widely validated DSS for laparoscopic liver resection (LLR). However, these studies only validated the 4 difficulty levels and did not validate the 12-point difficulty index of the system. To address current limitations in the studies validating the Iwate difficulty scoring system (DSS), we performed an international multicenter study to validate the Iwate DSS across both its four difficulty levels and 12-point difficulty index.

Methods: A retrospective cohort study of 22,252 patients undergoing LLR across 64 centers worldwide between 2005 and 2021 was performed. Baseline characteristics and perioperative outcomes were analyzed across the four difficulty levels and 12-point difficulty index of the Iwate DSS.

Results: A total of 14,759 patients met the inclusion criteria. The main indications for LLR were hepatocellular carcinoma/intrahepatic cholangiocarcinoma (52.8 %), and metastatic tumors liver (26.5 %). In terms of underlying liver pathology, 5127 patients (34.8 %) had liver cirrhosis, and 1214 patients (8.3 %) had portal hypertension. Intraoperative outcomes (operation time, blood loss, blood transfusion, use of Pringles maneuver and open conversion) and postoperative outcomes (length of stay, morbidity, major complications, and 90-day mortality) significantly increased with stepwise increases across the four difficulty levels (P < 0.001) and 12-point difficulty index (P < 0.001). These trends remained significant following adjustment for baseline characteristics (P < 0.001).

Conclusion: The Iwate DSS 12-point difficulty index and four difficulty levels correlated well with LLR difficulty as determined by key surrogate perioperative measures.

Keywords: Difficulty score; Iwate criteria; Laparoscopic liver resection; Perioperative outcomes; Validation.

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Conflict of interest statement

Conflicts of interest i) Dr Goh BK has received travel grants and honorarium from Johnson and Johnson, Olympus and Transmedic the local distributor for the Da Vinci Robot. ii) Dr Marino MV is a consultant for CAVA robotics LLC. iii) Johann Pratschke reports a research grant from Intuitive Surgical Deutschland GmbH and personal fees or non-fiNAcial support from Johnson & Johnson, Medtronic, AFS Medical, Astellas, CHG Meridian, Chiesi, Falk Foundation, La Fource Group, Merck, Neovii, NOGGO, pharma-consult Peterson, and Promedicis. iv) Moritz Schmelzle reports personal fees or other support outside of the submitted work from Merck, Bayer, ERBE, Amgen, Johnson & Johnson, Takeda, Olympus, Medtronic, Intuitive. v) Asmund Fretland reports receiving speaker fees from Bayer. vi) Fernando Rotellar reports speaker fees and support outside the submitted work from Integra, Medtronic, Olympus, Corza, Sirtex and Johnson & Johnson. vii) Troisi RI reports speaker fees and support outside the submitted work from Integra, Stryker, Medtronic, Medistim, MSD.

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