Pulmonary involvement in polymyositis and in dermatomyositis

OBJECTIVE: To assess prevalence, characteristics, and predictive factors of pulmonary involvement in polymyositis (PM) and dermatomyositis (DM). METHODS: The medical records of 55 consecutive patients with PM and DM between 1983 and 1996 were reviewed. The criteria for diagnosis of PM and DM were based upon Bohan and Peter criteria. RESULTS: Twenty-two patients (40%) developed lung impairment with a mean of 17 months after onset of PM and DM. The 3 main types of pulmonary disorders were interstitial lung disease (41%), ventilatory insufficiency with bronchopneumonia (22.8%), and alveolitis (with pulmonary function tests revealing restrictive pattern, low diffusing capacity, and normal computerized tomography) (36.2%). Both morbidity and mortality rates were as high as 40 and 27%, respectively, in PM and DM patients with lung involvement. Moreover, for the group with pulmonary diseases, serum GOT and ferritin levels were higher (p = 0.01 and p = 0.02) and the presence of anti-Jo-1 antibody and characteristic microangiopathy were more frequent (p < 0.05 and p = 0.0002). CONCLUSION: This series reveals both high prevalence (40%) and severity of pulmonary involvement in PM and DM. Our findings also suggest that high serum GOT and ferritin levels, presence of anti-Jo-1 antibody and characteristic microangiopathy may have predictive value and should encourage the search for pulmonary dysfunction and interstitial lung disease in patients with PM and DM.