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.