[Side effects and efficiency of 15 mg and 25 mg methotrexate per week in chronic polyarthritis].

To examine the rate of side effects and the dose dependence of side effects 185 consecutive patients with active rheumatoid arthritis were randomized to receive 15 mg (group A) or 25 mg (group B) methotrexate (MTX) per week and studied prospectively over 12 months. Dose adjustments were performed according to tolerability and efficacy. With 168 patients eligible for evaluation the rate of withdrawal for any reason was 26% in group A and 27% in B. Withdrawal due to side effects occurred in 16% versus 18%, dose reduction due to side effects in 10% versus 9%. The higher dose was associated with a significantly higher rate of gastrointestinal side effects (28% vs. 17%, p < 0.05) and a tendency for more frequent elevations of transaminases. Other side effects were not dose dependent. A significantly higher rate of dose reduction due to improvement (35% versus 10%, p < 0.001), a more rapid decline of morning stiffness, and a higher number of patients reporting marked improvement are evidence in favour of higher therapeutic efficacy of the higher dose. In conclusion, an initial dose of 25 mg MTX/week is not associated with a higher rate of limiting side effects as compared with 15 mg/week. The efficacy of doses up to 25 mg/week should be examined in more detail.