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P634 What Are The Long Term Outcomes of Perianal Crohn's Fistulae Treated with Anti-TNF Therapies?

N.A. Yassin*1, A. Askari2, L. Ferrari2, J. Warusavitarne2, O. Faiz2, R. Phillips2, A. Hart3

1St Mark's Hospital, Colorectal Surgery & IBD Unit, London, United Kingdom, 2St Mark's Hospital, Colorectal Surgery, London, United Kingdom, 3St Mark's Hospital, IBD Unit, London, United Kingdom


Fistulising perianal Crohn's disease (CD) is a challenging condition to treat and a multidisciplinary approach to treatment is frequently required. Little is known regarding the long-term efficacy of anti-TNF therapy for this group of patients. We evaluated the clinical and radiological outcomes and the effects of biological therapy on our cohort of patients.


A local database of 180 consecutive patients with Crohn's disease treated at our institution between 2005 and 2014 was established.


Patients underwent Infliximab therapy (61%), Adalimumab therapy (6%) or switched between the two (33%) for the treatment of the perianal fistulas.

Clinical remission was noted in 47% of patients with a classification of a simple fistula, and 22% of those with a complex fistula (p<0.01). Radiological remission however was noted in 28% of patients with a simple fistula and 5% of those with a complex fistula (p<0.01)

After a median follow-up period of 52 months (range 1-163), 32% of patients were in clinical remission, 74% of patients had a clinical response to treatment and the recurrence rate after remission was 12%. Radiological remission was noted in 14% of patients, response in 62% of patients and recurrence of 4.7% over a median of 37 months (range 3-101) MRI follow-up.

The median time to clinical remission was 21 months (IQR 11-36), and time to radiological remission was 20 months (IQR 1-88). Whereas the median time to clinical response was 25 (IQR 18.8-31.2), and radiological response median time was 19 months (IQR 13-24). Factors influencing the time to clinical response were fistula duration (p=0.03), and the current use of immunomodulators (p=0.02).

Patients who did not have a Montreal classification of L1 disease were 2.68 times more likely to achieve clinical remission (CI=1.23-5.86, p=0.01), Having no proctitis at the start of biological therapy predicts a twofold increase in the likelihood of clinical remission in this group of patients (CI=1.01-6.18, p=0.04)


This is the largest single centre study using both clinical and radiological outcomes on perianal Crohn's fistulae. About three-quarters of patients had clinical response to biological therapy, whereas two-third had a radiological response. Twelve percent of the patients had a clinical recurrence after remission, whereas only 4.7% had radiological recurrence after remission on MRI scanning. A time delay is noted between clinical and radiological response to treatment. Response to anti-TNF therapy for fistulising perianal Crohn's disease should be monitored with regular MRI imaging as an adjunct to clinical follow-up.