P1189 Clinical features and surgical necessity rate of fistulising perianal disease in newly diagnosed patients with Crohn's disease: Interim analysis of inception cohort registry study of patients with Crohn's disease (iCREST-CD)
Authors: Takatsu N , Yamamoto T , Nakase H , Shinzaki S , Watanabe K , Fujii T , Okamoto R , Matsuoka K , Yamada A , Kunisaki R , Matsuura M , Shiga H , Bamba S , Mikami Y , Shimoyama T , Motoya S , Torisu T , Kobayashi T , Ohmiya N , Saruta M , Matsuda K , Matsumoto T , Maemoto A , Yoshigoe - S , Tsuchiya H , Nishimura R , Murata Y , Hisamatsu T 
Published: January 2024

Abstract

Background
Fistulising perianal diseases (FPD) are common in patients with Crohn's disease (CD) in Asia, but the treatment pattern and the proportion of patients who develop new FPD after diagnosis are not clear. An interim analysis of a large registry study was performed to evaluate the difference in prognosis between patients with and without FPD at diagnosis of CD and the incidence and timing of onset of FPD in patients without FPD at diagnosis of CD.

Methods
iCREST-CD is a prospective, non-interventional, longitudinal, observational registry study conducted at 19 tertiary centres in Japan. Patients newly diagnosed with CD from June 2016 to June 2020 based on the diagnostic criteria of the Japanese Guidelines, aged ≥16 years at the time of informed consent with no prior exposure to biologics were enrolled. Patient demographics, clinical data, disease activity and medical treatment record up to June 2022 were used. FPD were defined as a perianal abscess and/ or perianal fistula.

Results
Of the 662 patients with newly diagnosed CD for whom with or without FPD were recorded, 236 patients [35.6%] had FPD at diagnosis (Group A). Of the 426 patients who did not have FPD at the time of diagnosis, 32 patients developed FPD during the observation period (Group B), and 394 patients did not develop it (Group C). The mean age [SD] at the time of CD diagnosis in Groups A, B, and C was 25.0 [8.6], 31.6 [15.5], and 31.7 [14.4] years, respectively. The proportion of female was 21.2%, 34.4% and 37.8%, respectively; L2 disease location was 14.6%, 23.3%, and 18.0%, respectively; and B2+B3 disease behaviour was 27.5%, 53.1%, and 40.6%, respectively. The mean CRP (mg/L [SD]) was 28.5 [33.8], 42.4 [43.6], and 27.1 [36.3], respectively. For disease activity based on HBI score, the proportion with moderate (8≦HBI≦16) and severe (16&lt;HBI) activity was 17.6%, 36.8%, and 24.0%, respectively (Table).
The rate of patients who developed FPD was 4.5% (19 patients) by 12 months and 6.5% (28 patients) by 24 months, respectively (Figure).
In Group A with a mean observation period (month [SD]) of 27.9 [8.8], 12.3% and 17.3% of patients needed perianal surgery at 12 and 24 months, respectively. In Group B with a mean observation period of 29.7 [7.7], 7 FPD patients [21.9%] subsequently underwent perianal surgery, all within 12 months of FPD onset.

Conclusion
Patients who did not have a perianal abscess or fistula at the time of their CD diagnosis but later developed these problems tended to have numerically higher CD activity at the time of diagnosis and were more likely to require perianal surgery. These results suggest that patients with highly active CD are at risk of developing new FPD and should be carefully monitored.