An Observational Study on the Clinical Characteristics and Prognosis of Patients With Interstitial Lung Disease Secondary to Dermatomyositis and Antisynthetase Syndrome

Objective: Identify the clinical characteristics and prognostic factors in patients with idiopathic inflammatory myopathy (IIM) combined with interstitial lung disease (ILD). Methods: IIM‐ILD patients who were hospitalized at Guangxi Medical University from January 2017 to December 2022 were retrospectively analyzed and classified as having dermatomyositis (DM)‐ILD or ‐ILD. Clinical and laboratory results were analyzed. Results: There were 39 males and 111 females, the mean age of disease onset was 50.4 ± 12.3 years, and the median disease duration was 3 months (range: 1–6). Ninety‐seven patients had DM‐ILD, and 53 had ASS‐ILD. The DM‐ILD group had 72% positivity for the anti‐MDA5 antibody and 5.2% positivity for the anti‐Mi‐2 antibody; the ASS‐ILD group had 67.9% positivity for the anti‐Jo‐1 antibody and 17% positivity for the anti‐EJ antibody. Muscle symptoms, skin ulcers, rash, rapidly progressing interstitial lung disease (RP‐ILD), and elevated levels of serum carcinoembryonic antigen were more common in DM‐ILD patients (all p < 0.05). However, pericardial effusion and pleural effusion, elevated creatinine kinase, and elevated C‐reactive protein were more common in ASS‐ILD patients. After a median follow‐up of 15.5 months, there were more deaths in the DM‐ILD group (42.3% vs. 13.2%, p < 0.001). Multivariate Cox regression analysis showed that RP‐ILD, dyspnea, and the usual interstitial pneumonia type of ILD had negative associations with overall survival (OS), and arthralgia had a positive association with OS (all p < 0.05). Conclusion: DM‐ILD patients were more prone to secondary RP‐ILD and skin ulcers, had milder symptoms of myositis and less severe serositis, and had lower survival rates than the ASS‐ILD patients. RP‐ILD, dyspnea, and the usual interstitial pneumonia type of ILD had adverse effects on prognosis, but arthralgia was a protective factor.