Impact of Sex, Serostatus, and Smoking on Risk for Rheumatoid Arthritis-Associated Interstitial Lung Disease Subtypes.

OBJECTIVES:RA-associated interstitial lung disease (RA-ILD) includes multiple subtypes with varying histopathology, prognosis, and potential treatments. Limited research has investigated risk factors for different RA-ILD subtypes. Therefore, we examined demographic, serologic, and lifestyle associations with RA-ILD subtypes. METHODS:We systematically identified RA-ILD cases and RA-noILD controls in the Brigham RA Sequential Study and Mass General Brigham Biobank RA cohort. We determined RA-ILD subtype (usual interstitial pneumonia [UIP], nonspecific interstitial pneumonia [NSIP], and other/indeterminate) through chest high-resolution computed tomography imaging pattern. We investigated associations between demographic, lifestyle, and serologic factors and major RA-ILD subtypes using multivariable logistic regression. RESULTS:Among 3328 RA patients, we identified 208 RA-ILD cases and 547 RA-noILD controls. RA-UIP was associated with older age (OR 1.03 per year, 95%CI 1.01 to 1.05), male sex (OR 2.15, 95%CI 1.33 to 3.48), and seropositivity (OR 2.08 95%CI 1.24 to 3.48) while RA-NSIP was significantly associated only with seropositive status (OR 3.21, 95%CI 1.36 to 7.56). Non-fibrotic ILDs were significantly associated with smoking (OR 2.81, 95%CI 1.52 to 5.21). Having three RA-ILD risk factors (male, seropositive, smoking) had an OR of 6.89 (96%CI 2.41 to 19.7) for RA-UIP compared to having no RA-ILD risk factors. CONCLUSIONS:Older age, seropositivity, and male sex were strongly associated with RA-UIP while RA-related autoantibodies were associated with RA-NSIP. These findings suggest RA-ILD sex differences may be driven by RA-UIP and emphasizes the importance of further studies to clarify RA-ILD heterogeneity and optimize screening and treatment approaches.