The light at the end of the tunnel: a single-operator learning curve analysis for per oral endoscopic myotomy

Background: Per oral endoscopic myotomy (POEM) represents a natural orifice transluminal endoscopic surgery approach to Heller myotomy. Our center was the first to offer POEM outside of Japan, allowing us to accumulate what is likely the highest single-operator POEM volume in the United States. Objective: To define the POEM learning curve of a gastroenterologist by using a larger data set and more detailed statistical analysis than used in 2 other reports of POEM performed by surgeons. Design: Prospective cohort study. Setting: Tertiary-care academic medical center. Patients: We analyzed the first 93 consecutive POEMs on patients with achalasia aged > 18 years without contraindications to POEM performed by a single operator from October 2009 to November 2013. Interventions: (1) Efficiency estimation via cumulative sum (CUSUM) analysis, (2) mastery estimation via penalized basis-spline regression and CUSUM analysis, (3) correlation of operator experience with clinical outcomes (Eckardt score improvement, lower esophageal sphincter pressure reduction) and technical errors (accidental mucosotomy rate), and (4) unadjusted and adjusted regression analysis to assess how patient characteristics affected procedure time by using a generalized linear model. Main Outcome Measurements: Clinical outcomes, procedure time, technical errors. Results: Efficiency was attained after 40 POEMs and mastery after 60 POEMs. When we used the adjusted regression analysis, only case number (operator experience) significantly affected procedure time (P < .0001). Improvements in clinical outcomes were excellent but not significantly affected by operator experience, as was the case with accidental mucosotomies. Procedure time was not significantly affected by age, sex, achalasia stage, baseline lower esophageal sphincter pressure, baseline Eckardt score, prior treatment of achalasia, prior botulinum toxin injection, incidence of accidental mucosotomies, length of myotomy, or type of knife used (all P > .05). Limitations: Our analysis may underestimate the number of POEMs required to achieve mastery for operators with limited or no endoscopic submucosal dissection experience. Conclusion: These results offer thresholds for efficiency and mastery of a single gastroenterologist operator that may guide the efforts of novice POEM operators.