BACKGROUND A procedure-based laparoscopic liver resection (LLR) classification (IMM classification) stratified 11 different LLR procedures into 3 grades. IMM classification assessed the difficulty of LLR differently than an index-based LLR classification (IWATE criteria), which scored each procedure on an index scale of 12. We validated the difference of 3 IMM grades using an external cohort, evaluated the IMM classification using the scores of the IWATE criteria, and compared the performance of IMM classification with the IWATE criteria and the minor/major classification. METHODS Patients undergoing LLR without simultaneous procedures were selected from a prospectively maintained database at the Institut Mutualiste Montsouris (IMM cohort) and from the database of 43 Japanese institutions (JMI cohort). Surgical and postoperative outcomes were evaluated according to the 3 IMM grades using the JMI cohort. The 11 LLR procedures included in the IMM classification were scored according to the IWATE criteria. The area under the curves (AUCs) for surgical and postoperative outcomes were compared. RESULTS In the JMI (n = 1867) cohort, operative time, blood loss, conversion rate, and major complication rate were significantly associated with a stepwise increase in grades from I to III (all, P < 0.001). In the IMM (n = 433) and JMI cohorts, IMM grades I, II, and III corresponded to three low-scoring, two intermediate-scoring, and six high-scoring LLR procedures as per the IWATE criteria, respectively. Mean ± standard deviation among the IMM grades were significantly different: 3.7 ± 1.4 (grade I) versus 7.5 ± 1.7 (grade II) versus 10.2 ± 1.0 (grade III) (P < 0.001) in the IMM cohort and 3.6 ± 1.4 (grade I) versus 6.7 ± 1.5 (grade II) versus 9.3 ± 1.4 (grade III) (P < 0.001) in the JMI cohort. The AUCs for surgical and postoperative outcomes are higher for the 3-level IMM classification than for the minor/major classification. CONCLUSIONS The difference of 3 IMM grades with respect to surgical and postoperative outcomes was validated using an external cohort. The 3-level procedure-based IMM classification was in accordance with the index-based IWATE criteria. The IMM classification performed better than the minor/major classification for stratifying LLR procedures.

中文翻译：

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腹腔镜肝切除术基于三级过程的分类的验证和执行。

背景基于手术的腹腔镜肝切除术（LLR）分类（IMM分类）将11种不同的LLR手术分为3个等级。与基于索引的LLR分类（IWATE标准）相比，IMM分类评估LLR的难度不同，后者基于12的索引量表对每个过程进行评分。我们使用外部队列验证了3个IMM等级的差异，使用对IWATE标准进行评分，并将IMM分类与IWATE标准和次要/主要分类的效果进行比较。方法从蒙塔苏里州互助研究所（IMM队列）的前瞻性维护数据库和日本43个机构（JMI队列）的数据库中选择未同时进行LLR的患者。使用JMI队列根据3个IMM等级评估手术和术后结局。根据IWATE标准对IMM分类中包括的11个LLR程序进行了评分。比较了手术和术后结果的曲线下面积（AUC）。结果在JMI（n = 1867）队列中，手术时间，失血量，转化率和主要并发症发生率与I级至III级的逐步升高显着相关（所有，P <0.001）。在IMM（n = 433）和JMI队列中，按照IWATE标准，IMM I，II和III分别对应于三个低分，两个中等分和六个高分LLR程序。IMM等级之间的均值±标准差有显着差异：3.7±1.4（I级）与7.5±1.7（II级）与10.2±1。在IMM队列中为0（III级）（P <0.001），在JMI队列中为3.6±1.4（I级）与6.7±1.5（II级）对9.3±1.4（III级）（P <0.001）。三级IMM分类的手术和术后结果AUC高于次要/主要分类。结论使用外部队列验证了3种IMM级别在手术和术后结局方面的差异。3级基于过程的IMM分类符合基于索引的IWATE标准。对于分层LLR程序，IMM分类的性能优于次要/主要分类。三级IMM分类的手术和术后结果AUC高于次要/主要分类。结论使用外部队列验证了3种IMM级别在手术和术后结局方面的差异。3级基于过程的IMM分类符合基于索引的IWATE标准。对于分层LLR程序，IMM分类的性能优于次要/主要分类。三级IMM分类的手术和术后结果AUC高于次要/主要分类。结论使用外部队列验证了3种IMM级别在手术和术后结局方面的差异。3级基于过程的IMM分类符合基于索引的IWATE标准。对于分层LLR程序，IMM分类的性能优于次要/主要分类。