Early azathioprine therapy is no more effective than placebo for newly diagnosed Crohn's disease.

BACKGROUND & AIMS: A small placebo-controlled trial reported the efficacy of mercaptopurine therapy for children newly diagnosed with Crohn's disease, yet little is known about the efficacy of early thiopurine therapy in adults.

METHODS: We performed a prospective double-blind trial of adult patients with a recent (<8 weeks) diagnosis of Crohn's disease. Patients were randomly assigned to groups given azathioprine (2.5 mg · kg(-1) · day(-1), n = 68) or placebo (n = 63) at 31 hospitals from February 2006 to September 2009. Corticosteroids but no other concomitant medications were allowed for control of disease activity. The primary measure of efficacy was sustained corticosteroid-free remission.

RESULTS: After 76 weeks of treatment, 30 patients treated with azathioprine (44.1%) and 23 given placebo (36.5%) were in sustained corticosteroid-free remission (difference of 7.6%; 95% confidence interval, -9.2 to 24.4%; P = .48). The rates of relapse (defined as Crohn's Disease Activity Index score >175) and corticosteroid requirements were similar between groups. A post hoc analysis of relapse, defined as a Crohn's Disease Activity Index score >220, showed lower relapse rates in the azathioprine group than in the placebo group (11.8% vs 30.2%; P = .01). Serious adverse events occurred in 14 patients in the azathioprine group (20.6%) and 7 in the placebo group (11.1%) (P = .16). A larger percentage of patients in the azathioprine group had adverse events that led to study drug discontinuation (20.6%) than in the placebo group (6.35%) (P = .02).

CONCLUSIONS: In a study of adults with Crohn's disease, early azathioprine therapy was no more effective than placebo to achieve sustained corticosteroid-free remission but was more effective in preventing moderate to severe relapse in a post hoc analysis. EudraCT 2005-001186-34.