Background: Inflammatory myositis is a connective tissue disorder (CTD) primarily characterized by muscle inflammation, with potential involvement of extramuscular manifestations such as the skin, lungs, heart, and gastrointestinal tract.

Objectives: To assess the follow-up, treatment, and factors contributing to mortality in patients with ILD associated with inflammatory myositis.

Methods: This study included patients with ILD associated with CTD, who were enrolled in the GUR-ILD database from January 2016 to June 2023. The demographic and clinical data of the patient group diagnosed with inflammatory myositis were retrospectively analyzed and recorded from the GUR-ILD registry.

Results: A total of 190 patients were included in the GUR-ILD cohort. In this cohort group, 9 (4.7%) patients were diagnosed with inflammatory myositis. The median age of the patients (4 males/5 females) with inflammatory myositis was 64.4 (47.0-79.0) years, and disease duration was 15 (1-202) months. Four patients were diagnosed with inflammatory myositis before ILD, while 5 patients were diagnosed with inflammatory myositis and ILD concurrently. The presenting complaint in all patients was cough and dyspnea. In the evaluation of pulmonary function tests (PFTs), forced vital capacity (FVC) was found to be below 70 ml in 3 patients. Computed tomography (CT) findings revealed nonspecific interstitial pneumonia (NSIP) in 8 patients (88.9%) and usual interstitial pneumonia (UIP) in one patient (11.1%). The prevalence of ILD findings on CT images was 20% or less in 6 (66.7%) patients and above 20% in 3 (33.3%) patients at the time of diagnosis. All patients received at least one immunosuppressive (IS) treatment for ILD. Three patients were treated with azathioprine, 2 with rituximab and cyclosporine, 5 with mycophenolate mofetil, one with tocilizumab and one with intravenous immunoglobulin. During the follow-up, nintedanib was added as antifibrotic therapy for one patient. In addition to IS treatment, all patients frequently received prednisolone at a dosage ranging from 7.5 to 30 mg per day. Jo-1 antibody was positive in 4 patients, MDA-5 antibody was positive in 2 patients, while PM-SCL and SRP antibodies were positive in one patient each. During the follow-up period, 3 patients died. Among them, 2 patients with positive MDA-5 antibodies died due to disease activation and respiratory failure resulting from PCP (pneumocystis carinii pneumonia) infection (Table 1).

Conclusion: While the utilization of IS therapies at different stages enhances our treatment approach, it’s crucial to note that MDA-5 antibody positivity remains a significant factor contributing to swift and progressive lung involvement, leading to increased mortality.

REFERENCES: NIL.

Acknowledgements: NIL.

Disclosure of Interests: None declared.