Low-dose methotrexate compared with azathioprine in the treatment of rheumatoid arthritis. A twenty-four-week controlled clinical trial.

Forty-two patients with definite or classic rheumatoid arthritis entered a prospective 24-week, double-blind, parallel clinical trial, followed by an 18-month open phase. All subjects had active synovitis that was unresponsive to nonsteroidal antiinflammatory medications and conventional slow-acting antirheumatic drugs. Initial treatment with azathioprine (AZA), 100 mg/day, or methotrexate (MTX), 10 mg/week, orally, was adjusted at predefined intervals. Both treatment groups showed statistically significant improvement at week 24, compared with baseline status, in all 9 clinical outcome variables. There were no apparent statistically significant differences in these outcome variables between the 2 treatment groups. There was a trend toward a more marked and rapid improvement in the MTX-treated group. Radiologic evidence of progression of joint damage was similar in both treatment groups at 24 and 52 weeks. Four of the 42 patients (2 receiving MTX and 2 receiving AZA) discontinued the study because of side effects, and 1 MTX-treated patient withdrew because of personal reasons. Outcome measures at week 52 (open phase) were not statistically different from those at week 24. Twenty-three patients were still taking the medication at week 104. We found that AZA and MTX were similarly effective in the treatment of rheumatoid arthritis, and that this beneficial effect was maintained for up to 2 years in most patients.