P0432Is Crohn’s Disease Location Stable Over Time? Findings from a Population-Based Study

Background It is commonly accepted that Crohn’s disease (CD) location remains stable over time when assessed using the Montreal classification. The aim of this study was to evaluate, in a large population-based cohort, the risk of disease extension according to the Montreal classification as well as by individual colonic segments. Methods All patients diagnosed with CD before the age of 17 between 1988 and 2011, identified from a prospective population-based registry and who had undergone at least two colonoscopies, were retrospectively assessed until 2013. The cumulative probability of extension at 5 years was estimated (i) for each Montreal classification category (L1, L2, and L3), and (ii) by individual colonic segments. Patients were censored at the time of colonic surgery. The prognostic impact of colorectal extension was evaluated after propensity score matching for sex, age, follow-up duration, diagnostic period, disease location at diagnosis, and presence of perianal disease. Results Among 1007 patients diagnosed with CD, 707 had at least two colonoscopies (median follow-up 10.2 years [IQR, 5.7–15.3]). Ileal (L1), colonic (L2), and ileocolonic (L3) disease locations at diagnosis represented 16%, 26%, and 58% of patients, respectively. At 5 years, these proportions were 12%, 20%, and 68%. Among patients with ileal (L1) or colonic (L2) disease at diagnosis, the 5-year risk of extension to an ileocolonic (L3) location was 29% (95% CI [23%–35%]) (L1 to L3: 16% [8%–24%]; L2 to L3: 38% [29%–45%]). At 5 years, the cumulative probability of extension to at least one additional colonic segment was 32% [27%–36%], to the rectum 20% [15%–24%], and to pancolitis 17% [13%–20%]. Rectal extension (n = 118/399) was not significantly associated with an increased risk of perianal disease (HR = 2.0, 95% CI [0.4–10.9]). Extension to pancolitis (n = 131/524) was not associated with an increased risk of colectomy (HR = 0.5, 95% CI [0.1–5.5]). Conclusion In this population-based cohort of patients diagnosed with pediatric-onset CD, disease extension according to the Montreal classification occurred in nearly one-third of patients by 5 years. One-third experienced extension to at least one additional colonic segment, one-fifth to the rectum, and one-sixth to pancolitis. Conflict of interest: Richard, Nicolas: Grant: Pfizer Personal Fees: Abbvie, Janssen, Takeda, MSD, Biogen, Amgen, Sandoz, Fresenius, Gilead, Celgene, Galapagos, Mylan, Tillots, Ferring, Pfizer, Hospira, CTMA, Boehringer, Lilly, Arena Non-financial Support: Abbvie, Janssen, Takeda, MSD, Galapagos, Ferring, Pfizer Leroyer, Ariane: None Prof. Fumery, Mathurin: No conflict of interest Ley, Delphine: No conflict of interest Dupont-Lucas, Claire: No conflict of interest Bertrand, Valérie: No conflict of interest Guillon, Nathalie: No conflict of interest Gower Rousseau, Corinne: None Paupard, Thierry: No conflict of interest Coevoet, Hugues: No conflict of interest Wils, Pauline: No conflict of interest Sarter, Hélène: Nothing to disclose Savoye, Guillaume: Other: MSD, Ferring, Pfizer, Takeda, Vifor