Ab0744 Association of Iga Rheumatoid Factors With Bronchopulmonary Involvement in Rheumatoid Arthritis From a French Observational Retrospective Cohort

Background: Extra-articular manifestations occurred in 40% of rheumatoid arthritis (RA) patients. Bronchopulmonary involvement is frequent and is associated with significant morbidity and mortality. High resolution-computed tomography (HR-CT) resulted as the most sensitive tool available to assess it 1. Levels of autoantibodies, including rheumatoid factors (RF) and anti-cyclic citrullinated peptides (anti-CCP), are associated with lung damage, even subclinical 2,3. However, there are no data about the potential link between the different isotypes of RF, notably IgA and lung manifestations, while the production of such autoantibodies occurs early in the preclinical phase of the disease. Objectives: To analyze the association between IgA RF and bronchopulmonary involvement in RA patients, considered alone or in combination with other autoantibodies. Methods: This retrospective monocentric cohort study included RA patients with IgA RF tested between 2009 and 2019. All data were collected from medical records. Patients' HR-CT have been analyzed by two radiologists to differentiate between parenchymal and bronchial lung damage. All discordant interpretations were adjudicated by an expert pulmonologist. Statistical analysis was carried out using an exact Fisher's test, supplemented by an adjusted logistic regression model. Results: Out of 2384 IgA RF assays performed, 183 patients were included in the study and separated into 2 groups according to IgA RF status (75 positive and 108 negative). The mean age of patients was 61 ±16 years and 72.1% were female. IgA RF+ patients were mostly comprised of male smokers, undergoing biologic treatments, and presented elevated levels of both RF IgM and anti-CCP. Overall lung damage was observed in 20.2% of the patients, from whom 14.5% and 8.7% had parenchymal and bronchial damage, respectively. No correlation was found between overall lung damage and IgA RF positive status (p = 0.19). While there was an association between concomitant positivity of anti-CCP and RF, whatever the isotype IgA or IgM, and parenchymal involvement, it was not found after adjustment. Older age and male gender seemed to be the only risk factors for overall lung damage, and age being the only factor associated to parenchymal damage. Conclusion: Our study did not show an association between the positivity/titers of IgA RF and bronchopulmonary involvement of RA. Until now, despite conflicting results, only high anti-CCP titers, and potentially presence of anti-carbamylated protein antibodies, have been found to be associated with risk of lung damage. REFERENCES: 1 Garrote-Corral S, Silva-Fernández L, Seoane-Mato D, et al. Screening of interstitial lung disease in patients with rheumatoid arthritis: A systematic review. Reumatol Clin (Engl Ed). 2022;18:587–96. 2 Bernstein EJ, Barr RG, Austin JHM, et al. Rheumatoid arthritis-associated autoantibodies and subclinical interstitial lung disease: the Multi-Ethnic Study of Atherosclerosis. Thorax. 2016;71:1082–90. 3 Matteson EL, Matucci-Cerinic M, Kreuter M, et al. Patient-level factors predictive of interstitial lung disease in rheumatoid arthritis: a systematic review. RMD Open. 2023;9:e003059. Acknowledgements: NIL. Disclosure of Interests: None declared.