OBJECTIVES: Interstitial lung disease (ILD) is one of the most serious pulmonary complications associated with connective tissue diseases (CTDs). While immunosuppressants are commonly prescribed in these patients, evidence supporting their efficacy in slowing lung function decline is limited, especially when compared to or combined with antifibrotics, and practices vary. This study aims to describe the prevalence of ILD-treating therapies, such as immunosuppressants and antifibrotics, in patients with CTD-ILD following their ILD diagnosis.

METHODS: This retrospective cohort study used Optum Clinformatics® US claims data from 2017 through 2022. The study cohort comprised adult patients diagnosed with CTD followed by ILD, irrespective of a progressive phenotype. The index date was the initial ILD diagnosis date. At least 12-months of continuous enrollment were required before the index date (baseline period) and after the index date (follow-up period). Patients were categorized into one of four treatment groups based on the drug classes prescribed during the follow-up period: ILD-treating immunosuppressants only, antifibrotics only, both, and neither. The prevalence of each group and medication use during the follow-up period were descriptively analyzed.

RESULTS: The study included 6,070 CTD-ILD patients, with a mean age of 70.9 years and 4,597 (75.7%) female patients. Rheumatoid arthritis was the most common underlying CTD (49.8%). The prevalence of patients receiving ILD-treating immunosuppressants only, antifibrotics only, both, and neither were 4,131 (68.1%), 11 (0.2%), 70 (1.2%), and 1,858 (30.6%), respectively. Among patients who have received any ILD-treating immunosuppressants, corticosteroids were most prescribed (96.7%), followed by other immunosuppressants (18.1%) and biologic disease modifying antirheumatic drugs (7.0%).

CONCLUSIONS: The study findings demonstrate a high prevalence of corticosteroid use in patients with CTD-ILD within the first 12 months following the ILD diagnosis, but lower utilization of steroid-sparing immunosuppressants. The limited use of antifibrotics and the significant number of patients receiving neither treatment indicate potential gaps in current treatment strategies.