MRI-Based Screening in a Retrospective Cohort Reveals Adverse Prognosis of Asymptomatic Perianal Fistulas in Crohn's Disease: A Long-term Follow-Up Study

Integration of Subphenotypic Lesions, Imaging-Based Healing Outcomes, and Biomarker Trajectories in a Retrospective Analysis of a Single-Center Retrospective Crohn's Disease Cohort

The goal of this observational study is to learn about the necessity of imaging screening for perianal fistula in Crohn's disease (CD) patients without perianal symptoms by comparing the natural history and long-term outcomes between those with asymptomatic perianal fistula (APF) and those with symptomatic perianal fistulizing Crohn's disease (PFCD).

The main questions it aims to answer are:

Does the early detection of asymptomatic perianal fistula through routine MRI screening lead to a better long-term prognosis in CD patients?

How do the clinical courses and long-term outcomes compare between CD patients with asymptomatic perianal fistula (APF) and those with symptomatic perianal fistula (PFCD)?

In accordance with our center's standard operating procedure (SOP), all patients with suspected CD underwent perianal MRI, regardless of perianal symptoms. Participants were retrospectively enrolled into a dedicated CD cohort at our center between 2010 and 2019. For this study, patients from this cohort who were diagnosed with perianal fistula at initial diagnosis will be retrospectively assessed. They were initially classified into the APF group or the symptomatic PFCD (control) group based on the presence of perianal symptoms at diagnosis. Using advanced statistical methods, the study will compare the risks of major disease complications, treatment initiation patterns, and overall disease progression between these two groups over years of follow-up.

Inclusion Criteria:

• CD patients diagnosed between January 1, 2010, and December 31, 2019;
• had perianal fistula confirmed by pelvic MRI within 3 months before or after initial CD diagnosis;
• prospective follow-up in our IBD center;

Exclusion Criteria:

• with incomplete records;
• less than 5 years of follow-up;