A Cochrane review [Abstract] 1 included 5 studies with a total of 698 subjects. Azathioprine compared to placebo reduced the number of patients who had relapses during the first year of treatment (relative risk reduction, RRR 20%, 95% CI 5% to 33%, n=499), at two years' (RRR =23%, 95% CI 12% to 33%, n=488) and three years' (RRR =18%, 95% CI 7% to 27%, n=415) follow-up. Data from only three small trials with a total of 87 patients were available to calculate the number of patients who progressed during the first two to three years. There was a statistically significant benefit (RRR = 42%, 95% CI 7% to 64%) of azathioprine therapy at three years' follow-up. Four patients (95% CI = 2 to 17) needed to be treated with azathioprine for three years to prevent one extra patient from having disability progression. Gastrointestinal disturbances, bone marrow suppression and hepatic toxicity were greater in the azathioprine group rather than in the placebo group; they were anticipated, and, by monitoring and dosage adjustment, were easily managed. Withdrawals due to adverse effects were few, occurring mostly during the first year of azathioprine treatment and mainly due to gastrointestinal intolerance.
Comment: The quality of evidence in downgraded by imprecise results (limited study size for each comparison). There are no studies with direct comparison between azathioprine and interferon beta in multiple sclerosis.
Primary/Secondary Keywords