Toward a Standardization of Learning Curve Assessment in Minimally Invasive Liver Surgery

Objective: The aim was to analyze the learning curves of minimal invasive liver surgery (MILS) and propose standardized reporting. Background: MILS offers benefits compared with open resections. For a safe introduction along the learning curve, formal training is recommended. However, definitions of learning curves and methods to assess it lack standardization. Methods: A systematic review of PubMed, Web of Science, and CENTRAL databases identified studies on learning curves in MILS. The primary outcome was the number needed to overcome the learning curve. Secondary outcomes included endpoints defining learning curves and characterization of different learning phases (competency, proficiency, and mastery). Results: Sixty articles with 12,241 patients and 102 learning curve analyses were included. The laparoscopic and robotic approach was evaluated in 71 and 18 analyses and both approaches combined in 13 analyses. Sixty-one analyses (60%) based the learning curve on statistical calculations. The most often used parameters to define learning curves were operative time (n=64), blood loss (n=54), conversion (n=42), and postoperative complications (n=38). Overall competency, proficiency, and mastery were reached after 34 [interquartile range (IQR) 19-56], 50 (IQR 24-74), and 58 (IQR 24-100) procedures, respectively. Intraoperative parameters improved earlier (operative time: competency to proficiency to mastery: -13%, 2%; blood loss: competency to proficiency to mastery: -33%, 0%; conversion rate (competency to proficiency to mastery; -21%, -29%), whereas postoperative complications improved later (competency to proficiency to mastery: -25%, -41%). Conclusions: This review summarizes the highest evidence on learning curves in MILS taking into account different definitions and confounding factors. A standardized 3-phase reporting of learning phases (competency, proficiency, and mastery) is proposed and should be followed.