Azathioprine with prednisone for polymyositis. A controlled, clinical trial

A controlled, prospective, double-blind, therapeutic trial of azathioprine was conducted in the initial therapy of polymyositis. Sixteen patients received 60 mg prednisone per day plus either azathioprine (2 mg/kg of body weight per day) or placebo for a period of 3 mth. Creatine phosphokinase (CPK) levels fell to normal slightly sooner in the placebo group, but not significantly so. The azathioprine group did not become significantly stronger (P = 0.58) and did not manifest significantly greater improvement of histopathologic features of muscle (P = 0.80) than the placebo group. Initial CPK elevations were significantly related to the degree of muscle inflammation (P = 0.037), but this was not the case at 3 mth (P > 0.05). Normalization of the CPK could not be equated with disease control. Type II fiber atrophy, attributed to steroid therapy, was more marked in women than in men (P < 0.03).