Retrospective study of polymyositis in Auckland over 10 years.

Twenty-nine patients with polymyositis and dermatomyositis seen at the three main hospitals in Auckland between 1967 and 1977 have been reviewed. Of the five diagnostic criteria used, weakness of proximal muscles (including neck flexors) was the single most important clinical diagnostic feature. The certainty of diagnosis was increased if investigations included a range of muscle enzymes, electromyography and muscle biopsy. The incidence of underlying malignancy was 10 percent. Patients with polymyositis or dermatomyositis with an associated connective tissue disorder responded better to treatment and pursued a more benign course.