Clinical Medicine Insights: Circulatory, Respiratory and Pulmonary Medicine

Although the relationship between muscle strength and exercise capacity has been demonstrated in dermatomyositis without lung dysfunction, little is known about the association between exercise capacity and interstitial lung disease in dermatomyositis. Eleven patients with dermatomyositis with interstitial lung disease without the manifestation of muscle weakness and 12 patients with idiopathic interstitial pneumonia underwent the 6-minute walk test (6MWT). PaO2, creatine kinase, percentage predicted 6MWT distance (6MWD%), and SpO2 at rest were similar between patients. Percentage predicted vital capacity, carbon monoxide diffusing capacity (DLCO%), and SpO2 after 6MWT were higher and exertional dyspnea was lower in patients with dermatomyositis than in patients with idiopathic interstitial pneumonia. SpO2 after 6MWT was positively correlated with 6MWD% in patients with dermatomyositis, while DLCO% and PaO2 were positively correlated with 6MWD% in patients with idiopathic interstitial pneumonia. Lung dysfunction in dermatomyositis might not be a major limitation factor in exercise capacity.