Role of myositis autoantibodies in diagnosing interstitial lung disease in patients with idiopathic inflammatory myopathies: a retrospective analysis.

Abstract

Background: Idiopathic inflammatory myopathies (IIMs) are frequently complicated by interstitial lung disease (ILD). The independent clinical significance of myositis autoantibody positivity remains incompletely defined.

Methods: We performed a retrospective cohort study of patients undergoing myositis autoantibody testing at a single tertiary center (1997-2022). Multivariable logistic regression assessed the association between antibody positivity and ILD. Subgroup analyses evaluated clinical phenotypes and radiologic patterns.

Results: Among 1,034 patients included in the analysis, 359 (34.7%) were positive for at least one myositis autoantibody and 365 (35.5%) had ILD. Antibody-positive patients were younger, more frequently female, and had a higher prevalence of ILD compared to antibody-negative patients (41.2% vs. 32.2%, p < 0.01). Myositis autoantibody positivity was independently associated with ILD (adjusted OR 1.78, 95% CI 1.33-2.37, p < 0.001). Increasing age, higher BMI, former smoking status, and Asian ethnicity were also associated with ILD. Among patients with ILD, antibody-positive individuals had a higher prevalence of systemic autoimmune features, including Raynaud's phenomenon, arthritis, and mechanic's hands, as well as higher inflammatory markers and more impaired pulmonary function.

Conclusion: Myositis autoantibody positivity is independently associated with ILD and identifies a distinct clinical phenotype. These findings should be interpreted in the context of the study's retrospective, single-center design.