OP15. Immunosuppressive co-treatment with adalimumab (ADA) may be more effective than ADA monotherapy for maintaining remission in Crohn's disease (CD)

C. Reenaers1, E. Louis1, J. Belaiche1, S. Keshav2, S. Travis2

1CHU Sart Tilman, Gastroenterology unit, Liege, Belgium; 2John Radcliffe Hospital, Gastroenterology unit, Oxford, United Kingdom

Background: There is clear benefit of combination therapy for infliximab (IFX) with immunosuppressive drugs (IS), whether commenced together, or later, but no data are available for ADA. The aim was to assess whether IS combotherapy (CoT) was more effective than monotherapy for Crohn's disease (CD) patients treated with ADA, using the semester approach.

Methods: Retrospective study of patients with CD (n = 181) treated for at least one year with ADA in Oxford, UK or Liege, Belgium. Treatment periods were divided into 6 month semesters and the treatment failure compared between semesters with or without CoT (thiopurines or methotrexate). ADA failure was defined as dose modification during therapy, drug modification, perineal complications, or surgery for active CD.

Results: 569 semesters were studied in 181 patients (Oxford n = 98, Liege 83), including 147 semesters in 45 patients having received CoT during the first semester. More patients in Oxford received CoT than Liege (OR: 4.82, p < 0.0001) and fewer females (OR 0.50, p = 0.01). When considering only patients on CoT during the first semester, treatment failures were less frequent in semesters with IS (20%) compared to semesters without IS (80%; OR 0.30, p = 0.02). This protective effect of the CoT was maintained over time (p = 0.01). When considering all the patients, CoT in the first semester was associated with a lower frequency of treatment failures (34% vs 66%, OR 0.69, p = 0.046) in univariate analysis but not in multivariate analysis. CoT later after induction of ADA was not associated with treatment failures. Female gender (OR 1.68, p = 0.01), previous surgery (OR 1.89, p = 0.001) and active perianal disease (OR 1.57, p = 0.02) were risk factors of failure on multivariate analysis. Although failures were less common in Oxford (OR 0.52, p = 0.001), more failures in Oxford had surgery (OR 8.85, p = 0.001) or perianal complications (OR 3.33, p = 0.01) and fewer had ADA weekly (OR 0.24, p = 0.0003) on multivariate analysis. The overall number of operations and perianal complications did not differ between CoT and ADA monotherapy. Thiopurines appeared more effective than methotrexate for preventing failure (OR 0.35, p = 0.03). The probablility of failure did not increase over the semesters (p = 0.86).

Conclusions: When it was given during the first semester, CoT with ADA in CD was associated with fewer semesters with treatment failures (essentially the need for dose escalation or treatment modification, but not the rate of surgery or perianal complications).