Natural History of Perianal Crohn's Disease: Long-term Follow-up of a Population-Based Cohort

International audience; BACKGROUND AND AIMS: The natural history of perianal Crohn’s disease (PCD) remains poorly described and is mainly based on retrospective studies from referral centres. The aim of this study was to assess the incidence, outcomes and predictors of the onset of PCD. METHODS: All incident cases of patients diagnosed with possible CD were prospectively registered from 1994 to 1997 in Brittany, a limited area in France. At diagnosis, the clinical features of perianal disease were recorded. All patient charts were reviewed from the diagnosis to the last clinic visit in 2015. RESULTS: Among the 272 out of 331 incident CD patients followed up, 51 (18.7%) patients had PCD at diagnosis. After a mean follow-up of 12.8 years, 93 (34%) patients developed PCD. The cumulative probabilities of perianal CD occurrence were 22%, 29%, and 32% after 1 year, 5 years, and 10 years, respectively. The cumulative probabilities of anal ulceration were 14%, and 19% after 1 year and 10 years, respectively. Extraintestinal manifestations were associated with the occurrence of anal ulceration. The cumulative probabilities of fistulizing PCD were 11%, 16%, and 19% after 1 year, 5 years, and 10 years, respectively. Extraintestinal manifestations, rectal involvement and anal ulceration were predictors of fistulizing PCD. The cumulative probability of developing anal stricture was 4% after 10 years. CONCLUSIONS: PCD is frequently observed during CD, in approximately one-third of patients. These data underline the need for targeted therapeutic research on primary perianal lesions (proctitis, anal ulceration) to avoid the onset of fistulizing perianal disease.