C39-16 Relationship of RA-associated Antibody Patterns With Lung Function in Patients With Interstitial Lung Disease (ILD)

Abstract Rationale Rheumatoid arthritis (RA) is a chronic systemic autoimmune disease often with pulmonary manifestations, including interstitial lung disease and airways disease. Rheumatoid factor (RF) is a key serologic marker in RA, and co-expression with other autoantibodies, such as CCP ab, may influence disease phenotype and severity. However, limited data exist on how differing antibody profiles impact pulmonary function outcomes. This study aims to compare lung function between patients positive for RF alone and those positive for RF with additional RA-associated antibodies. Methods A retrospective chart review of 56 patients with confirmed RA with ILD and available pulmonary function testing was conducted at Temple University Hospital. Patients were stratified into two groups: RF-only positive (RF+) and RF-positive with other RA-associated antibodies (RF+OAb). The RF+Oab group includes the presence of any of: CCP ab, Mut cit vimentin Ab Ser-aCnc, and 14.3.3. ETA protein. Demographic, serologic, and clinical variables were collected, including forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Results 38 individuals met the inclusion criteria for rheumatoid factor (RF) positivity with ILD on CT imaging. Nineteen patients had RF alone (RF+) and seven had RF with additional RA-associated antibodies (RF+OAb) with available serial pulmonary function data. The data were normally distributed, and group comparisons were performed using student’s t-test. Patients with RF+Oab exhibited significantly worse lung function over time compared to patients with RF+ antibodies, despite similar baseline lung function. Over follow-up, RF+ patients demonstrated a mean increase in FVC%Pred of 4.6 ± 13.3%, whereas the RF+OAb group showed a decline of 17.1 ± 12.9% (p ≈ 0.02). Similarly, mean FEV1%Pred increased by 2.1 ± 10.3% in the RF+ group but decreased by 15.4 ± 13.2% among RF+OAb patients (p ≈ 0.03). Conclusion This study suggests that multiple RA-associated antibody positivity was associated with greater functional decline compared to isolated RF positivity. The limitations of this study include its retrospective nature. Additionally, spirometry data were collected as part of routine clinical care; they were collected at varying times during the one-year follow-up period. Further research is needed to understand the extent and impact of autoimmune antibodies. This abstract is funded by: None