Changes of Crohn's disease phenotype over time.

Background - Crohn's disease is a clinically heterogeneous condition. Our aim was to identify the phenotype evolution of Crohn's disease over time according to the Montreal Classification and to precise predictive factors of the need for immunosuppressant treatment or surgery. Methods - We included Crohn's disease patients who were followed up for at least 5 years. We excluded patients who were lost to follow up before five. Patients were classified according to the Montreal classification for phenotype at diagnosis and five years later. The evolution of phenotype over time and the need for surgery, immunosuppressive or immunomodulatory drugs were evaluated. Results - One hundred twenty consecutive patients were recruited: 70 males and 50 females. At diagnosis, 68% of patients belong to A2 as determined by the Montreal classification. Disease was most often localized in the colon. The disease location in Crohn's disease remains relatively stable over time, with 93.4% of patients showing no change in disease location. Crohn's disease phenotype changed during follow up, with an increase in stricturing and penetrating phenotypes from 6% to 11% after 5 years. The only predictive factor of phenotype change was the small bowel involvement (OR=3.7 [1.2-7.6]). During follow-up, 82% of patients have presented a severe disease as attested by the use of immunosuppressive drugs or surgery. The factors associated with the disease severity were: small bowel involvement (L1), the stricturing (B2) and penetrating (B3) phenotypes and perineal lesions (OR=17.3 [8.4-19.7]; 12 [7.6-17.2]; 3[1.7-8.3] and 2.8 [2.2-5.1] respectively), without association with age, sex or smoking habits. Conclusion - Crohn's disease evolves over time: inflammatory diseases progress to more aggressive stricturing and penetrating phenotypes. The ileal location, the stricturing and penetrating forms and perineal lesions were predictive of surgery and immunosuppressant or immunomodulatory treatment.