Comparison between methotrexate and azathioprine in the treatment of chronic active Crohn's disease: a randomised, investigator-blind study

The efficacy of azathioprine in the treatment of chronic active Crohn's disease is well established. However, this drug has a long onset of action. Methotrexate has also been shown to be effective in chronic active Crohn's disease. The aim of this study was to evaluate the efficacy and safety of methotrexate in comparison with azathioprine, and to establish whether methotrexate has a shorter onset of action in this setting. METHODS: Patients with chronic active Crohn's disease were admitted to this investigator-blind study. Chronicity was defined as the need for steroid therapy of > or = 10 mg/day for at least 4 months during the preceding 12 months, with at least one attempt to discontinue treatment. The disease had to be clinically active at entry, with a Crohn's Disease Activity Index of > or = 200. Six patients treated with azathioprine and methotrexate, respectively, were found to have enterocutaneous and perianal fistulas. At entry, all patients received prednisolone (40 mg once a day) which was tapered over a period of 12 weeks unless their clinical condition deteriorated. All patients were randomised to receive i.v. methotrexate 25 mg/week, or oral azathioprine 2 mg/kg per day, for a 6-month follow-up period. After the first 3 months, methotrexate was switched to oral administration maintaining the same dose. The primary efficacy outcome considered was the proportion of patients entering first remission after 3 and 6 months of therapy. Clinical remission was defined as the lack of need for steroid treatment and a Crohn's Disease Activity Index score of < or = 150 points at each scheduled visit. RESULTS: In the 54 patients (26 F, 28 M, mean age 34 years, range 18-60) randomly assigned to methotrexate (n=27) or azathioprine (n=27), no statistically significant difference was found between the two treatment regimens with respect to remission rate after 3 (methotrexate 44%, azathioprine 33%, p=0.28, (95% CI, 0.369-0.147), and 6 months (methotrexate 56%, azathioprine 63%, p=0.39, 95% CI, 0.187-0.335), respectively. Six patients withdrew from therapy due to adverse events: 3/27 (11%) in methotrexate and 3/27 (11%) in azathioprine. Drug-related adverse events (asthenia, nausea and vomiting) that did not require withdrawal from therapy were more frequent in the methotrexate group (azathioprine: 2/27 (7%); methotrexate: 12/27 (44%), p=0.00009). The frequency of these adverse events was comparable during the intravenous or oral administration of the drug. CONCLUSIONS: This study confirms that methotrexate is effective in inducing remission in patients with chronic active Crohn's disease, therapeutic efficacy being comparable, but not faster, than that of azathioprine.