Standard-dose versus low-dose azathioprine in the treatment of Crohn's disease: A prospective randomized study

Azathioprine (AZA) is widely used to treat Crohn's disease (CD) with a recommended dose of 2-2.5 mg/kg per day for Westerners. Asian patients are suggested to take a lower dose. However, many clinicians reported poor efficacy with a reduced dose. This study aimed to explore a efficient and safe dose of AZA providing the best efficacy for Chinese CD patients.

Fifty patients with active CD were enrolled and randomized into two groups (n = 25 each). All other treatments were the same except that group A received 1 mg/kg per day and group B took 2 mg/kg per day of AZA. Complete remission (CR) rate and response rate at weeks 12, 24 and 48 were assessed by using intent-to-treat (ITT) and per-protocol (PP) analyses. Adverse events and recurrence rate were also evaluated.

At week 48, CR rate and response rate in group B (ITT: 50.0% and 59.1%; PP: 57.9% and 68.4%) were significantly higher than those in group A (ITT: 13.0% and 17.4%; PP: 16.7% and 22.2%) (P < 0.05). Nine adverse events occurred, including pancreatitis (n = 1), arthritis (n = 2) and myelosuppression (n = 6). There was no significant difference in adverse events between the two groups. However, recurrence rate was significantly higher in group A than in group B (P = 0.042).

AZA 2 mg/kg per day is more appropriate than 1 mg/kg per day for Chinese CD patients with a high efficacy, a low recurrence rate and not increased adverse events.