title: The incidence and prevalence of inflammatory bowel disease among U.S. veterans: a national cohort study.
abstract: BACKGROUND
  Temporal trends in incidence and prevalence of Crohn's disease (CD) and ulcerative colitis (UC) in the United States have been reported only in regional populations. The Veterans Affairs (VA) health care system encompasses a national network of clinical care facilities. The aim of this study was to identify temporal trends in the incidence and prevalence of CD and UC among VA users using national VA data sets.
  
  
  METHODS
  Veterans with CD and UC were identified during fiscal years 1998 to 2009 in the national VA outpatient and inpatient files. Incident and prevalent cases were identified by diagnosis code, and age-standardized and gender-standardized annual prevalence and incidence rates were estimated using the VA 1998 population as the standard population.
  
  
  RESULTS
  The total of unique incident cases were 16,842 and 26,272 for CD and UC, respectively; 94% were men. The average annual age-standardized and gender-standardized incidence rate of CD was 33 per 100,000 VA users (range, 27-40), whereas the average for UC was 50 per 100,000 VA users (range, 36-65). In 2009, the age-standardized and gender-standardized point prevalence rate of CD was 287 per 100,000 VA users, whereas the point prevalence of UC was 413 per 100,000 VA users.
  
  
  CONCLUSIONS
  Prevalence of CD and UC increased 2-fold to 3-fold among VA users between 1998 and 2009. The incidence of UC decreased among VA users from 1998 to 2004 but has remained stable from 2005 to 2009. The incidence of CD has remained stable during the observed time period.
authors: Houston VA HSR&D Center of Excellence, Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA. jkhou@bcm.edu
authors: Jason K
authors: JK
authors: Hou
authors: Jennifer R
authors: JR
authors: Kramer
authors: Peter
authors: P
authors: Richardson
authors: Minghua
authors: M
authors: Mei
authors: Hashem B
authors: HB
authors: El-Serag
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003093:Colitis, Ulcerative / Q000175:diagnosis / Q000453:epidemiology*; D003424:Crohn Disease / Q000175:diagnosis / Q000453:epidemiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011379:Prognosis; D014481:United States / Q000453:epidemiology; D014728:Veterans / Q000706:statistics & numerical data*