title: Learning curve for peroral endoscopic myotomy.
abstract: OBJECTIVE
  Although peroral endoscopic myotomy (POEM) is being performed more frequently, the learning curve for gastroenterologists performing the procedure has not been well studied. The aims of this study were to define the learning curve for POEM and determine which preoperative and intraoperative factors predict the time that will be taken to complete the procedure and its different steps.
  
  
  METHODS
  Consecutive patients who underwent POEM performed by a single expert gastroenterologist for the treatment of achalasia or spastic esophageal disorders were included. The POEM procedure was divided into four steps: mucosal entry, submucosal tunneling, myotomy, and closure. Nonlinear regression was used to determine the POEM learning plateau and calculate the learning rate.
  
  
  RESULTS
  A total of 60 consecutive patients underwent POEM in an endoscopy suite. The median length of procedure (LOP) was 88 minutes (range 36 - 210), and the mean (± standard deviation [SD]) LOP per centimeter of myotomy was 9 ± 5 minutes. The total operative time decreased significantly as experience increased (P < 0.001), with a "learning plateau" at 102 minutes and a "learning rate" of 13 cases. The mucosal entry, tunneling, and closure times decreased significantly with experience (P < 0.001). The myotomy time showed no significant decrease with experience (P = 0.35). When the mean (± SD) total procedure times for the learning phase and the corresponding comparator groups were compared, a statistically significant difference was observed between procedures 11 - 15 and procedures 16 - 20 (15.5 ± 2.4 min/cm and 10.1 ± 2.7 min/cm, P = 0.01) but not thereafter. A higher case number was significantly associated with a decreased LOP (P < 0.001).
  
  
  CONCLUSIONS
  In this single-center retrospective study, the minimum threshold number of cases required for an expert interventional endoscopist performing POEM to reach a plateau approached 13.
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Mohamad
authors.initials: M
authors.lastname: El Zein
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Vivek
authors.initials: V
authors.lastname: Kumbhari
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Saowanee
authors.initials: S
authors.lastname: Ngamruengphong
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA.
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Carson
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Ellen
authors.initials: E
authors.lastname: Stein
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Alan
authors.initials: A
authors.lastname: Tieu
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Yamile
authors.initials: Y
authors.lastname: Chaveze
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Amr
authors.initials: A
authors.lastname: Ismail
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Sameer
authors.initials: S
authors.lastname: Dhalla
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: John
authors.initials: J
authors.lastname: Clarke
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Anthony
authors.initials: A
authors.lastname: Kalloo
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Marcia Irene
authors.initials: MI
authors.lastname: Canto
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology, Johns Hopkins Hospital, Baltimore, Maryland, USA.
authors.forename: Mouen A
authors.initials: MA
authors.lastname: Khashab