P498. Efficacy of anti TNF-treatment for fistulizing Crohn's disease
J. Maljaars1, I. Molendijk1, C. Baeten2, R. Veenendaal1, A. Van der Meulen1, 1Leiden University Medical Center, Gastroenterology and Hepatology, Leiden, Netherlands, 2Leiden University Medical Centre, Surgery, Leiden, Netherlands
Anti-TNF is the best currently available medical treatment modality for treating perianal fistulizing Crohn's disease (CD). However, whether the efficacy is comparable between adalimumab (ADA) and infliximab (IFX) has never been studied. Furthermore, little is known about the long-term outcomes of anti-TNF in these patients.
In this retrospective cohort study, we identified all patients with CD who used anti-TNF in 2011. Demographics and received anti-TNF treatment were noted and response (sustained reduction in fistula effusion or remission) and remission (closure of fistula at physical examination) were determined. Survival analysis was performed by Kaplan–Meier and Log-Rank test, covariate analysis with a Cox regression model.
From 288 patients with CD who are current or previous users of anti-TNF, 103 patients were identified with fistulizing CD. In 58 patients, anti-TNF treatment was started during a period of active fistulizing disease. These patients had a median age of 26.5 yrs [interquartile range (IQR) 21.2–35] and 57% (33/58) were female. The majority, 87%, had a perianal fistula.
IFX was started in 81% (47/58) patients and ADA was started in 19% (11/58) patients The overall response to treatment was 65% (38/58): 64% (30/47) of the patients treated with IFX and 55% (6/11) of the patients treated with ADA (p = 0.54).
Use of immune-modulator co-medication did not influence the response rate (p = 0.62), nor did age, sex or duration of fistula existence prior to start anti-TNF.
In 16 out of 19 patients (84%) who did not respond, anti-TNF treatment was switched (14 times IFX to ADA, twice ADA to IFX). After this switch, 38% (6/16) of the patients responded to anti-TNF treatment. This was significantly lower when compared to the success rate of the first treatment (p < 0.001).
In total, 44 (38 plus 6) patients were in remission due to anti-TNF. These patients were followed for a median of 45 months (IQR 19.25–84.75). In this period, 25% (11/44) of the patients relapsed.
Risk of relapse was not affected by patient age or sex, smoking or type of anti-TNF used for induction of remission. There was a trend towards a greater risk for relapse in patients in whom anti-TNF was switched during remission-induction (RR 1.56, p = 0.054) in the univariate analysis; in multivariate analysis, no effect was present.
Response to anti-TNF treatment in fistulizing Crohn's disease is 65% and is not significantly different between ADA and IFX. When the first anti TNF is not successful, an additional 38% of patients respond after switch of therapy. After long-term follow up, 25% of the patients will experience a relapse of fistulizing disease.