Ab0774 Analysis of a Cohort of Patients With Rheumatoid Arthritis and Interstitial Lung Disease

Background: Rheumatoid arthritis (RA) is an autoimmune disease that, in addition to affecting the synovial joints, produces systemic manifestations associated with a worse prognosis of the disease. Interstitial lung disease (ILD) is the most common associated pulmonary manifestation. Autoantibodies, such as rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA), may appear in the serum of these patients, which are useful for early diagnosis and prognosis, due to their good sensitivity and specificity and their relationship with structural damage and extra-articular manifestations. Objectives: -To determine the presence of ACPA and RF in patients with RA and ILD, as well as to analyze the clinical, analytical and radiological characteristics and the time of disease evolution in these patients. -To evaluate the statistical association (SA) between ACPA and RF titers with the different radiological patterns of UIP (usual interstitial pneumonia) and NON-UIP and with the fibrosing patterns progressive fibrosing UIP and fibrotic NSIP (non-specific interstitial pneumonia). Methods: Descriptive study of 60 patients with RA-ILD see in an ILD Clinic, collected from 01/01/2020 to 01/01/2023. RF titers were categorized as: 24 U/ml High Positive. ACPA titers were categorized as 0-10 U/ml Negative, 10-299 U/ml Low Positive, >300 U/ml High Positive and Not Performed. On the other hand, the ILD has been divided based on HRCT (high-resolution computed tomography) results: UIP and NON-UIP pattern. The time of evolution (TE) of the disease was defined as the difference in years between the date of diagnosis of RA and the date of diagnosis of ILD (when the latter appears later) or between the date of diagnosis of ILD and the date of diagnosis of RA (when the latter is diagnosed later). Both are quantitative variables with normal distribution (Kolmogorov-Smirnov test). Quantitative variables are expressed as mean (SD) and dichotomous variables as percentages (%). The association of qualitative variables was analyzed using the Chi-square test. Statistical analysis with SPSS. Approved by the Ethics Committee. Results: The baseline characteristics of the patients are summarized in Table 1. Regarding the SA between the RF titers and the HRTC patterns UIP or NON-UIP, it could not be demonstrated between both (p=0.59). Likewise, it was not found between RF titers with respect to the progressive fibrosing pattern (p=0.38). The analysis of the SA between the ACPA titles and the HRTC pattern was not significant (p=0.05). However, if we do not include in the analysis patients who have not undergone ACPA, we found a statistically significant association (p=0.26) (low positive ACPA plus NON-UIP 57% or plus UIP 24%; high positive ACPA plus NON-UIP 21% or plus UIP 58%). Likewise, there is no association between ACPA titers with respect to the progressive fibrosing pattern (p=0.70). Conclusion: Our results differ from those published in the literature, and a multidisciplinary approach is essential for the early diagnosis and follow-up of these patients. Prospective studies with a larger number of patients, are needed to determine how different factors in patients with RA affect the development of ILD. REFERENCES: NIL. Table 1. Acknowledgements: NIL. Disclosure of Interests: None declared.