Clinical Characteristics and Risk Factors of Polymyositis and Dermatomyositis Combined with Interstitial Lung Disease in Patients Residing in the Northeast Sichuan Province of China.

BACKGROUND: Polymyositis (PM) and dermatomyositis (DM) are non-suppurative and autoimmune inflammatory diseases of striated muscle. Interstitial lung disease (ILD) is a group of heterogeneous diseases that mainly involve the pulmonary interstitium, alveoli, and/or bronchioles, also known as diffuse parenchymal lung disease (DPLD). A significant cause of death in persons with polymyositis (PM) and dermatomyositis (DM) is concurrent interstitial lung disease (ILD). However, research on the clinical characteristics and associated influencing factors of PM/DM combined with ILD (PM/DM-ILD) is currently scarce in China. OBJECTIVE: The study aimed to probe the clinical features and risk factors of PM/DM-ILD. METHODS: The data of 130 patients with PM/DM were gathered. General medical status, clinical symptoms, laboratory parameters, high-resolution CT, therapeutic outcomes, and prognoses were retrospectively reviewed in patients with PM/DM with (ILD group) and without (NILD) ILD. RESULTS: The age of the ILD group (n=65) was more than the NILD group (n=65), and the difference was statistically significant; there were no significant between-group variations in the PM/DM ratio, sex, or duration of the disease. The initial symptoms were arthritis and respiratory symptoms in the ILD group, and myasthenia symptoms in the NILD group. Incidences of Raynaud's phenomenon, dry cough, expectoration, dyspnea on exertion, arthritis, fever, total globulin (GLOB), erythrocyte sedimentation rate (ESR), and anti-Jo-1 antibody rate were higher for ILD; however, albumin (ALB), creatine kinase aspartate aminotransferase activity ratio (CK/AST) and CK levels were significantly lower in the ILD group. Bivariate logistic regression analysis showed age, dry cough, arthritis, dyspnea on exertion, anti-Jo-1 antibody, and elevated GLOB to be independent risk factors for ILD among patients with PM/DM. CONCLUSION: Advanced age, dry cough, arthritis, dyspnea on exertion, anti-Jo-1 antibody positivity, and elevated GLOB level are risk factors for PM/DM-ILD. This information could be utilized to carefully monitor changing lung function in these patients.