title: Achalasia: incidence, prevalence and survival. A population-based study.
abstract: BACKGROUND
  Studies of achalasia epidemiology are important as they often yield new insights into disease etiology. In this study, our objective was to carry out the first North American population-based study of achalasia epidemiology using a governmental administrative database.
  
  
  METHODS
  All residents in the province of Alberta, Canada receive universal healthcare coverage as a benefit. The provincial health ministry, Alberta Health and Wellness, maintains a central stakeholder database of patient demographic information and physician billing claims. We defined an achalasia case as a billing claim submitted for the years 1996-2007 with an ICD-9-CM code of 530.0 or 530 and a Canadian Classification of Procedure treatment code of 54.92A (endoscopic balloon dilation) or 54.6 (esophagomyotomy). A preliminary validation study of the case definition demonstrated a sensitivity of 85% and specificity of 99% for known cases and controls.
  
  
  RESULTS
  A total of 463 achalasia cases were identified from 1995 to 2008 (59.6% males). Mean age at diagnosis was 53.1 years. In 2007, the achalasia incidence was 1.63/100,000 (95% CI 1.20, 2.06) and the prevalence was 10.82/100,000 (95% CI 9.70, 11.93). We observed a steady increase in the overall prevalence rate from 2.51/100,000 in 1996 to 10.82/100,000 in 2007. Survival of achalasia cases was significantly less than age-sex matched population controls (P < 0.0001).
  
  
  CONCLUSIONS
  Using a population-based approach, the incidence and prevalence of treated achalasia is 1.63/100,000 and 10.82/100,000, respectively. The disease appears to have a stable incidence but a rising prevalence. Survival of achalasia cases is significantly less than age-matched healthy controls.
authors.affiliation: GI Motility Laboratory, Royal Alexandra Hospital, University of Alberta, Edmonton, AB, Canada. dan.sadowski@ualberta.ca
authors.forename: D C
authors.initials: DC
authors.lastname: Sadowski
authors.forename: F
authors.initials: F
authors.lastname: Ackah
authors.forename: B
authors.initials: B
authors.lastname: Jiang
authors.forename: L W
authors.initials: LW
authors.lastname: Svenson
mesh_terms: D000293:Adolescent; D000328:Adult; D017668:Age of Onset; D000368:Aged; D000369:Aged, 80 and over; D000416:Alberta / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D004931:Esophageal Achalasia / Q000453:epidemiology*; D005260:Female; D006801:Humans; D015994:Incidence; D038801:International Classification of Diseases; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D015996:Survival Rate