[Outcome in patients with interstitial lung disease and polymyositis-dermatomyositis--a subgroup with poor prognosis]

To determine the role of interstitial lung disease (ILD) in the outcome of polymyositis-dermatomyositis (PM/DM), we studied 41 patients who had radiographic evidence of ILD among 51 patients with PM/DM. The patients were divided into 3 groups according to therapy: progressive, no change, or improved. Those classified as progressive had significantly higher rates of skin and lung symptoms, milder muscle symptoms, and lower levels of muscle enzymes than the other 2 groups, and none was positive for the anti-Jo-1 autoantibody. Nine patients with DM died of respiratory failure; they had low serum creatine kinase levels, no anti-Jo-1 antibodies, and a rapidly progressive course before death. Autopsy findings were obtained in 7 patients, and all had diffuse alveolar damage as the main pulmonary histological finding. A subgroup of patients with PM/DM-ILD have a poor prognosis, and ILD in PM/DM is an important prognostic factor.