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

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.

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Key information

Conditions

Crohn's Disease Crohn Disease Digestive System Diseases Gastroenteritis Gastrointestinal Diseases Inflammatory Bowel Diseases Intestinal Diseases

Sex eligibility

All sexes

Study type

Observational

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

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;

Treatment and study plan

Primary outcomes

CD-related intestinal surgery

Time frame: Follow-up began at diagnosis and ended at death, loss to follow-up, or December 31, 2024, whichever occurred first.

CD-related intestinal surgeries included intestinal resection, ostomy creation, and similar procedures. The onset of a CD-related intestinal surgery was defined as the time point when it was first detected on imaging during follow-up.

Secondary outcomes

intestinal stricture

Time frame: Follow-up began at diagnosis and ended at death, loss to follow-up, or December 31, 2024, whichever occurred first.

A diagnosis of intestinal stricture is established if it meets either of the following criteria: (1) Imaging criteria: the narrowed segment exhibits at least two of these three features compared to the adjacent proximal bowel segment: >50% reduction in lumen diameter, >25% increase in bowel wall thickness, or pre-stricture dilation >3 cm; or (2) Endoscopic criterion: the stricture is impassable to the endoscope.The onset of a CD-related intestinal stricture was defined as the time point when it was first detected on imaging during follow-up.
intestinal fistula

Time frame: Follow-up began at diagnosis and ended at death, loss to follow-up, or December 31, 2024, whichever occurred first.

An intestinal fistula is defined as an abnormal communication between bowel loops or between the bowel and other organs, identified on imaging. The onset of a CD-related intestinal fistula was defined as the time point when it was first detected on imaging during follow-up.
Medically difficult-to-treat status

Time frame: Follow-up began at diagnosis and ended at death, loss to follow-up, or December 31, 2024, whichever occurred first.

Medically difficult-to-treat status was defined according to the IOIBD criteria as the failure of at least two biologic or small-molecule agents with different mechanisms of action. The date of initiating a third mechanism-of-action agent was used as the time of diagnosis for medically difficult-to-treat status.
clinically prioritized composite endpoint

Time frame: Follow-up began at diagnosis and ended at death, loss to follow-up, or December 31, 2024, whichever occurred first.

Given that the outcome events were multidimensional and differed in clinical importance, the conventional composite endpoint approach was deemed inappropriate; therefore, win ratio method was adopted. The events were prioritized in descending order of clinical importance as follows: CD-related intestinal surgery > intestinal fistula > intestinal stricture > medically difficult-to-treat CD. Because the presence of perianal symptoms is the direct indication for perianal surgery, perianal surgical events were not included in the prioritized composite outcome to avoid reverse causality. This priority order was determined based on clinical practice. To mitigate potential bias introduced by a fixed priority order, sensitivity analyses were performed using alternative orderings.

Sponsors and collaborators

Lead sponsor

Sixth Affiliated Hospital, Sun Yat-sen University

Other

Registry information

Official study title

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

Important dates

Study start: 2010
Primary completion: 2019
Study completion: 2026
First posted: Apr 29, 2026
Registry last updated: Apr 29, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed