Azathioprine in the treatment of chronic polyarthritis: longterm results and adverse effects in 25 patients.

Azathioprine was administered to 25 patients with severe, progressive polyarthritis in a mean dose of 1.4 mg/kg daily. Synovitis improved in 12 patients. Psoriasis and vasculitis were also ameliorated. The therapeutic response did not correlate with dose, concomitant steroid therapy or leukopenia, the latter occurring in nine patients. Carcinoma developed in two patients, after four and nine months of treatment respectively. Low dose azathioprine therapy may be useful in the management of some patients with refractory polyarthritis, but the unsettled issue of oncogenesis requires further investigation.