Incidence of Spondyloarthropathy in Patients with Crohnʼs Disease: A Population-Based Study

Purpose: Spondyloarthropathy (SpA) is an important extraintestinal manifestation of inflammatory bowel disease (IBD), although the frequency is uncertain. We aimed to assess the cumulative incidence and clinical spectrum of SpA in patients with Crohn's disease (CD) in a population-based study. Methods: The medical records of a population-based cohort of Olmsted County, MN residents diagnosed with CD from 1970 through 2004 were reviewed. Patients were followed longitudinally until moving from Olmsted County, death, or December 31, 2010. We recorded data on musculoskeletal symptoms and disease and we used the European Spondyloarthropathy Study Group and New York criteria to identify patients with SpA. The cumulative incidence of SpA subsequent to CD diagnosis was estimated using the Kaplan-Meier method. Results: The cohort included 309 patients with CD of which 50.2% were women and the median age at diagnosis of CD was 30.1 years (range 8-91). Prior to CD diagnosis, the prevalence of spondyloarthropathy was 1.3% (95% confidence interval [CI], 0.4%-3.3%). The cumulative incidence of a diagnosis of spondyloarthropathy after an established diagnosis of CD was 2.6% (95% CI, 0.7%-4.5%) at 10 years, 6.2% (2.5%-9.9%) at 20 years, and 10% (3.3%-16.2%) at 30 years. The 10 year cumulative incidence of ankylosing spondylitis was 0 while both the 20 year and 30 year cumulative incidences were 1.4% (95% CI, 0-3.3%). Sacroiliitis, oligoarthritis and polyarthritis were observed in 1.6%, 2.9% and 1.9% of patients in the post-CD diagnosis period, respectively. Conclusion: We have for the first time defined the actual cumulative incidence of SpA in CD using complete medical record information in a populationbased cohort. The cumulative incidence of all forms of SpA increased to about one in 10 patients by 30 years from CD diagnosis and features of SpA generally occurred within the first 10 years after CD diagnosis. Our results emphasize the importance of maintaining a high level of suspicion for SpA when following patients with Crohn's disease.