title: Analysis of the learning curve for peroral endoscopic myotomy for esophageal achalasia: Single-center, two-operator experience.
abstract: OBJECTIVE
  Peroral endoscopic myotomy (POEM) has emerged as an advanced technique for the treatment of achalasia, and defining the learning curve is mandatory.
  
  
  METHODS
  From August 2011 to June 2014, two operators in our institution (A&B) carried out POEM on 35 and 33 consecutive patients, respectively. Moving average and cumulative sum (CUSUM) methods were used to analyze the POEM learning curve for corrected operative time (cOT), referring to duration of per centimeter myotomy. Additionally, perioperative outcomes were compared among distinct learning curve phases.
  
  
  RESULTS
  Using the moving average method, cOT reached a plateau at the 29th case and at the 24th case for operators A and B, respectively. CUSUM analysis identified three phases: initial learning period (Phase 1), efficiency period (Phase 2) and mastery period (Phase 3). The relatively smooth state in the CUSUM graph occurred at the 26th case and at the 24th case for operators A and B, respectively. Mean cOT of distinct phases for operator A were 8.32, 5.20 and 3.97 min, whereas they were 5.99, 3.06 and 3.75 min for operator B, respectively. Eckardt score and lower esophageal sphincter pressure significantly decreased during the 1-year follow-up period. Data were comparable regarding patient characteristics and perioperative outcomes.
  
  
  CONCLUSIONS
  This single-center study demonstrated that expert endoscopists with experience in esophageal endoscopic submucosal dissection reached a plateau in learning of POEM after approximately 25 cases.
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Houning
authors.initials: H
authors.lastname: Lv
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Zhao
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Zhongqing
authors.initials: Z
authors.lastname: Zheng
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Wang
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Yang
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Xihui
authors.initials: X
authors.lastname: Jiang
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Lin
authors.initials: L
authors.lastname: Lin
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.affiliation: Department of Gastroenterology and Hepatology, Tianjin Medical University General Hospital, Tianjin, China.|Tianjin Institute of Digestive Disease, Tianjin Medical University General Hospital, Tianjin, China.
authors.forename: Bangmao
authors.initials: B
authors.lastname: Wang
mesh_terms: D000328:Adult; D004931:Esophageal Achalasia / Q000601:surgery*; D049630:Esophageal Sphincter, Lower / Q000601:surgery*; D004945:Esophagoscopy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D059032:Learning Curve; D008297:Male; D000074433:Myotomy / Q000379:methods*; D057605:Natural Orifice Endoscopic Surgery / Q000379:methods*; D061646:Operative Time; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
keywords: achalasia; cumulative sum; learning curve; moving average; peroral endoscopic myotomy