title: Analysis of a learning curve and predictors of intraoperative difficulty for peroral esophageal myotomy (POEM).
abstract: BACKGROUND
  Peroral esophageal myotomy (POEM) is an endoscopic surgical operation for achalasia. Here, we analyze a single-series POEM learning curve and examine which preoperative patient factors are predictive of operative difficulty.
  
  
  METHODS
  Two surgeons performed all POEM procedures conjointly. Nonlinear regression was used to determine the learning curve for procedure time. Preoperative patient characteristics were correlated with outcomes.
  
  
  RESULTS
  Thirty-six POEM procedures were performed. Total operative time did not decrease over the course of the series (mean 112 ± 36 min). Time required to complete the procedural steps of submucosal access and myotomy did decrease with experience, both exhibiting a "learning rate" of seven cases. The incidence of inadvertent mucosal perforations and the number of clips required both decreased with experience. Postoperative Eckardt scores at 1-year follow-up decreased over the course of the series. Prior endoscopic treatment, symptom duration, and esophageal width were all independently predictive of longer procedure time. Preoperative symptom duration was also positively associated with inadvertent mucosal perforation and the number of clips required.
  
  
  CONCLUSIONS
  In this series, overall procedure time did not decrease with experience and may not be an important marker of procedural skill for POEM. Prior endoscopic treatment, longer symptom duration, and esophageal dilatation may result in increased operative difficulty during POEM.
authors.affiliation: Department of Surgery, Northwestern University Feinberg School of Medicine, 676 North Saint Clair Street, Suite 650, Chicago, IL, 60611, USA.
authors.forename: Ezra N
authors.initials: EN
authors.lastname: Teitelbaum
authors.forename: Nathaniel J
authors.initials: NJ
authors.lastname: Soper
authors.forename: Fahd O
authors.initials: FO
authors.lastname: Arafat
authors.forename: Byron F
authors.initials: BF
authors.lastname: Santos
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Kahrilas
authors.forename: John E
authors.initials: JE
authors.lastname: Pandolfino
authors.forename: Eric S
authors.initials: ES
authors.lastname: Hungness
mesh_terms: D000328:Adult; D002983:Clinical Competence; D004931:Esophageal Achalasia / Q000601:surgery*; D004939:Esophageal Perforation / Q000209:etiology*; D049630:Esophageal Sphincter, Lower / Q000601:surgery*; D004945:Esophagoscopy; D004947:Esophagus / Q000473:pathology*; D005260:Female; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology*; D059032:Learning Curve; D008297:Male; D008875:Middle Aged; D061646:Operative Time; D009929:Organ Size; D013525:Surgical Instruments; D013997:Time Factors