Predictors of long-term outcomes of radiologically defined perianal fistulizing Crohn’s disease treated with antitumor necrosis factor-alpha agents based on Parks’ classification

Background and aims Perianal fistulizing Crohn’s disease (PFCD) leads to significant disability. Data assessing healing of complex PFCD based on pelvic MRI using Parks’ classification remains sparse. We aimed to assess the frequency of closure of fistula tract on MRI in patients treated with antitumor necrosis factor alpha antagonists and identify predictors of poor response. Materials and methods We retrospectively identified patients registered in the Saudi Inflammatory Bowel Disease Information System registry, who were diagnosed as PFCD based on MRI and treated with infliximab or adalimumab. Fistulae were classified based on Parks’ classification and response to treatment was determined as full, partial, or no response, after at least 12 months of treatment. Results Out of 960 patients, 61 had complex PFCD that required treatment with an anti-TNF agent. The median age was 27 years (range: 14–69 years) and the median duration of disease was 6.2 ± 5.8 years. A full response to treatment was achieved in 27 (44.4%), whereas 10 patients (16.3%) had partial response and 24 (39.3%) had no response. On univariable analysis, a statistically significant association was observed between poor fistula response and low BMI, rectal involvement, fistulae classification, and the presence of an abscess. According to multivariable regression, only low BMI predicted poor fistulae outcome (odds ratio = 1.37, 95% confidence interval: 0.69–0.98). Conclusion Less than half of this cohort of patients with PFCD achieved complete radiological fistula healing with anti-TNF therapy. Low BMI appears to be the only predictor of poor outcome.