Anti-Inflammatory Versus Antifibrotic Therapies for the Management of Rheumatoid Arthritis-Associated Interstitial Lung Disease: Protocol for a Systematic Review and Meta-Analysis.

Background: Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease that affects approximately 0.5% to 1% of the population in the United States and Northern Europe. Interstitial lung disease (ILD) is the most common and severe pulmonary manifestation of RA, collectively referred to as RA-associated ILD (RA-ILD). RA-ILD contributes significantly to morbidity and mortality and often presents with a variable clinical course. Although corticosteroids and disease-modifying antirheumatic drugs (DMARDs) remain the cornerstone of RA management, their role in RA-ILD is less clearly defined. In contrast, antifibrotic therapies such as pirfenidone and nintedanib, initially developed for idiopathic pulmonary fibrosis, are now being explored for their potential in treating fibrosing variants of RA-ILD. Despite increasing clinical use, no systematic review has comprehensively compared the safety and efficacy of antifibrotic versus anti-inflammatory therapies in chronic RA-ILD.

Objective: This study aims to compare the impact of antifibrotic and anti-inflammatory therapies on lung function, radiologic progression, clinical outcomes, and safety in patients with chronic RA-ILD.

Methods: This study will follow PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines and is registered with PROSPERO (CRD42024583847). A comprehensive search of PubMed, Embase, and the Cochrane Library will be conducted for studies published between January 1991 and August 2024. Eligible studies will include adult patients (aged ≥18 years) with a diagnosis of RA and confirmed ILD based on radiological or histopathological findings who have been treated with either antifibrotic or anti-inflammatory therapies. The PECOS (Population, Exposure, Comparator, Outcome, Study Design) framework will be used to define inclusion criteria. The primary outcomes assessed in this review will include the following pulmonary function parameters: forced vital capacity, forced expiratory volume in 1 second, and diffusing capacity of the lungs for carbon monoxide. Anti-inflammatory therapies will be stratified into corticosteroids, conventional synthetic DMARDs, and biologic DMARDs to account for heterogeneity. The Cochrane Risk of Bias 2 (RoB 2) and Risk of Bias in Non-randomized Studies - of Interventions (ROBINS-I) tools will be used for quality assessment, and GRADE (Grading of Recommendations Assessment, Development, and Evaluation) methodology will be used to evaluate the certainty of evidence.

Results: The literature search and screening commenced in August 2024, and data extraction is underway. The final results are expected by December 2025.

Conclusions: This systematic review and meta-analysis will provide a comprehensive comparison of antifibrotic and anti-inflammatory therapies in the treatment of chronic RA-ILD. The findings will help inform clinical decision-making, support evidence-based treatment selection, and identify gaps in current research. By addressing both efficacy and safety, this review aims to guide future studies and improve patient outcomes for this complex and debilitating condition.

Trial registration: PROSPERO CRD42024583847; https://www.crd.york.ac.uk/PROSPERO/view/CRD42024583847.

International registered report identifier (irrid): DERR1-10.2196/73219.