Ab0369 evolution and prognosis of a cohort of patients with rheumatoid arthritis and subclinical interstitial lung disease.

Background Clinical RA-associated ILD (RA-ILD) presents in almost 10% of RA patients but subclinical RA-associated ILD is detected in 20-60%. The course of subclinical RA-ILD is not fully known. Some patients have disease progression to pulmonary symptoms, decreased respiratory function and high levels of morbidity and mortality. It is necessary to improve ways to determinate risk of progression in patients with subclinical RA-ILD. Objectives To describe a cohort of patients with clinical and subclinical Rheumatoid Arthritis-associated Interstitial Lung Disease (RA-ILD) and to compare the evolution and progression of both. Methods Ambispective observational study of a cohort of patients with RA-ILD confirmed by respiratory function tests (RFT) or high-resolution computed tomography (HRCT). From January 2019 to December 2021, all patients with these diagnoses from RA monographic clinic were included consecutively. Data on the onset of ILD were included retrospectively and data at the end of follow-up prospectively (last review). The % of patients who had subclinical ILD was evaluated, defined as pulmonary involvement due to a requested HRCT without any previous respiratory symptoms. Outcome: evolution of the final ILD: (1) improvement (improvement in FVC ≥10% or DLCO ≥15% and no radiological progression); 2) no progression (stabilization or improvement in FVC ≤10% or DLCO <15% and no radiological progression); 3) progression (>10% worsening of FVC or >15% DLCO and radiological progression); or 4) death. Demographic variables, activity data (DAS28VSG accumulated 24 months prior to the diagnosis of ILD), RF and ACPA levels, RA severity data and treatments. Descriptive analysis, χ² or t-Student, and multivariate logistic regression analysis were performed to find predictive variables for the evolution of ILD. Results 50 patients with RA-ILD were included, 18 (36%) had subclinical ILD. The reason for requesting HRCT when they were diagnosed was abnormal chest X-ray in 11 patients (61.1%) and crackles in 7 patients (38.8%). The baseline characteristics of both groups at the time of ILD diagnosis and the evolution are shown in Table 1. The disease duration of the clinical ILD was longer than that of the subclinical ILD 5.6 (5.2) vs. 3.5 (2.4) years, p=0.053). At the moment of ILD diagnosis, the treatments were modified in 10 patients with clinical ILD and in 7 with subclinical ILD (p= 0.593): 8 abatacept, 7 rituximab and one antifibrotic drug were started. A total of 13 patients (26%) progressed and 25 (48%) showed a stabilization or improvement. Four patients died because of non-pulmonary causes. The only variable independently associated with the progression of ILD in the complete sample, adjusted for ACPA titres and age at diagnosis of ILD, was UIP pattern [OR = 5.3 (95%CI 1.1-26.2), p = 0.037] Conclusion In our cohort, the prevalence of subclinical ILD was high (36%). Although RFT at diagnosis of ILD, specifically DLCO levels, were higher in subclinical ILD than in clinical ILD, progression at the end of follow-up was the same in both groups. The UIP pattern was independently associated with progression. Therefore, taking into account that ILD is one of the main causes of mortality in our patients, we must actively search for this condition in order to treat it early and improve the prognosis. REFERENCES: NIL. Acknowledgements: NIL. Disclosure of Interests None Declared.