Prognostic factors in polymyositis/dermatomyositis. A computer-assisted analysis of ninety-two cases



An effort was made to identify all patients with polymyositis/dermatomyositis (PM/DM) admitted to hospitals in Israel from 1956–1976. The diagnosis of PM/DM was retrospectively reviewed in 92 (46 definite, 26 probable, and 20 possible) cases. The most common complaints and physical findings in the course of the disease were muscle weakness (86 patients), rash (53 patients), arthritis or arthralgia (39 patients), and dysphagia (35 patients). Elevated serum aldolase levels were found in 64% of the patients for whom data were available; 92% had abnormal electromyogram results, and 60.9% had muscle histopathology consistent with PM/DM. Malignancy was diagnosed in 13 patients. Malignancy, ischemic heart disease, and pulmonary complications were the most common causes of death. The actuarial survival curve was heterogeneous, with an accelerated mortality during the first year after diagnosis and a slower mortality during the following 7 years. Independent unfavorable prognostic signs were: failure to induce remission, leukocytosis, fever, older age, a shorter disease history, and dysphagia.