title: Incidence of spondyloarthropathy in patients with Crohn's disease: a population-based study.
abstract: OBJECTIVE
  Spondyloarthritis (SpA) is an extraintestinal manifestation of inflammatory bowel disease with significant clinical effects, although the frequency is uncertain. We assessed the cumulative incidence and clinical spectrum of SpA in patients with Crohn's disease (CD) in a population-based cohort.
  
  
  METHODS
  The medical records of a population-based cohort of Olmsted County, Minnesota, residents diagnosed with CD between 1970 and 2004 were reviewed. Patients were followed longitudinally until migration, death, or December 31, 2010. We used the European Spondylarthropathy Study Group, Assessment of Spondyloarthritis international Society (ASAS) criteria and modified New York criteria to identify patients with SpA. The Kaplan-Meier method was used to estimate the cumulative incidence of SpA following diagnosis of CD.
  
  
  RESULTS
  The cohort included 311 patients with CD (49.8% females; median age 29.9 yrs, range 8-89). Thirty-two patients developed SpA based on ASAS criteria. The cumulative incidence of SpA after CD diagnosis was 6.7% (95% CI 2.5%-6.7%) at 10 years, 13.9% (95% CI 8.7%-18.8%) at 20 years, and 18.6% (95% CI 11.0%-25.5%) at 30 years. The 10-year cumulative incidence of ankylosing spondylitis was 0, while both the 20-year and 30-year cumulative incidences were 0.5% (95% CI 0-1.6%).
  
  
  CONCLUSIONS
  We have for the first time defined the actual cumulative incidence of SpA in CD using complete medical record information in a population-based cohort. The cumulative incidence of all forms of SpA increased to approximately 19% by 30 years from diagnosis of CD. Our results emphasize the importance of maintaining a high level of suspicion for SpA when following patients with CD.
authors.affiliation: Department of Medicine, Division of Gastroenterology and Hepatology and Division of Rheumatology, Mayo Clinic, Rochester, Minnesota 55905, USA. loftus.edward@mayo.edu
authors.forename: Raina
authors.initials: R
authors.lastname: Shivashankar
authors.forename: Edward V
authors.initials: EV
authors.lastname: Loftus
authors.forename: William J
authors.initials: WJ
authors.lastname: Tremaine
authors.forename: Tim
authors.initials: T
authors.lastname: Bongartz
authors.forename: W Scott
authors.initials: WS
authors.lastname: Harmsen
authors.forename: Alan R
authors.initials: AR
authors.lastname: Zinsmeister
authors.forename: Eric L
authors.initials: EL
authors.lastname: Matteson
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D015331:Cohort Studies; D003424:Crohn Disease / Q000150:complications*; D018450:Disease Progression; D005260:Female; D006801:Humans; D015994:Incidence; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D012189:Retrospective Studies; D025242:Spondylarthropathies / Q000453:epidemiology* / Q000209:etiology*; D013997:Time Factors; D055815:Young Adult