title: Differences in the socio-economic distribution of inflammatory bowel disease and microscopic colitis.
abstract: OBJECTIVE
  Inflammatory bowel disease (IBD) and microscopic colitis are characterized by different geographical distributions across the USA. In this cross-sectional study we utilized demographic and socio-economic information associated with individual ZIP codes to further delineate the epidemiological characteristics of the two diseases.
  
  
  METHODS
  A total of 813 057 patients who underwent colonoscopy between 2008 and 2014 were extracted from an electronic database of histopathology reports. The prevalence of patients with IBD or microscopic colitis was expressed as percentage of the population associated with specific demographic (age, sex, ethnicity) and socio-economic characteristics (population size, housing value, annual income, tertiary education).
  
  
  RESULTS
  Both diseases were more common among subjects from ZIP codes with predominantly White residents and less common among subjects from ZIP codes with predominantly non-White residents such as Black, Hispanic and Asian. These ethnic variations were more pronounced in microscopic colitis than IBD. Markers of affluence, such as average residential house value and annual income, were positively associated with IBD and negatively with microscopic colitis. The prevalence of both diseases was positively correlated with tertiary education.
  
  
  CONCLUSIONS
  The occurrence of both IBD and microscopic colitis is influenced by environmental risk factors. The differences in the demographic, ethnic and socio-economic distributions of the two diseases suggest that different sets of risk factors affect the two diseases and that their aetiology is unrelated.
authors.affiliation: Miraca Life Sciences, Irving, Texas, USA.|Oregon Health and Science University, Portland, Oregon, USA.
authors.forename: A
authors.initials: A
authors.lastname: Sonnenberg
authors.affiliation: Miraca Life Sciences, Irving, Texas, USA.
authors.forename: K O
authors.initials: KO
authors.lastname: Turner
authors.affiliation: Miraca Life Sciences, Irving, Texas, USA.|University of Texas Southwestern Medical Center, Dallas, Texas, USA.
authors.forename: R M
authors.initials: RM
authors.lastname: Genta
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000368:Aged; D001213:Asian / Q000706:statistics & numerical data; D046728:Colitis, Microscopic / Q000453:epidemiology* / Q000209:etiology; D003113:Colonoscopy / Q000706:statistics & numerical data; D003430:Cross-Sectional Studies; D004522:Educational Status; D004777:Environment; D005260:Female; D062306:Geography, Medical / Q000706:statistics & numerical data; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data
keywords: Demographic characteristics; ZIP codes; environmental epidemiology; socio-economic risk factors