Low dose of azathioprine is effective to induce and maintain remission in active Crohn disease: A prospective observational study

Azathioprine (AZA) 2 to 2.5 mg/kg/d is recommended for European patients with Crohn disease (CD), but several Asian studies reported that low dose of AZA was also effective to treat CD. To confirm those observations, we perform this prospective observational study to compare the efficacy and safety of low and standard doses of AZA in the treatment of active CD. This was a prospective, open-labeled observational study. Two hundred twenty-six active CD patients were divided into 2 groups and treated with AZA 1.5 or 2.0 mg/kg/d respectively, combined with steroid therapy. Patients were followed up for 96 weeks. The complete remission (CR) rate, response rate, relapse rate, and adverse effect rate were assessed at weeks 24, 48, and 96 by intention-to-treat (ITT) analysis. Azathioprine 1.5 mg/kg/d showed no significant difference compared with AZA 2 mg/kg/d in CR rate, response rate and relapse rate by ITT analysis at week 24, 48, or 96 (all P > .05). Their adverse effect rates had no significant difference either (P > .05). Up to 21.7% (49/226) of the patients reported adverse events and 69.4% (34/49) of them were myelosuppresion. Azathioprine 1.5 mg/kg/d combined with steroids is as effective as AZA 2.0 mg/kg/d to induce remission of active CD in the first 6 months, and to maintain remission of inactive CD in the first 2 years, without increasing the recurrence of active CD after clinical remission. The most common adverse effect is myelosuppression.