Lung Involvement in Early Rheumatoid Arthritis, Analysis of the FINDRA Cohort

<bold>Background:</bold> The prevalence of lung involvement in rheumatoid arthritis (RA) is elusive and screening strategy remains unclear. <bold>Methods:</bold> The Factors of ILD in Newly Diagnosed RA (FINDRA, <ext-link>NCT04002765</ext-link>) study is a prospective multicentric trial that included patients with RA according to ACR/EULAR criteria diagnosed from 1 to 10 years before inclusion. Patients underwent respiratory evaluation that included an environmental questionnaire, HRCT with expiratory acquisition, pulmonary function tests and sampling for gene variants associated with RA-ILD (MUC5B, TERT, TOLLIP and FAM13A). HRCT were centrally reviewed for ILD, emphysema, bronchiolitis and nodules. <bold>Results:</bold> We included 258 patients (median age: 56 years-old). 71% were female, 49% were ex- or current smokers. 26% reported domestic or occupational exposure. 72% were seropositive. 76% were on methotrexate and 50% on another DMARD. We detected ILD in 38 patients (15%), emphysema in 51 (20%) and bronchiolitis in 89 (41%). Older age, male sex, higher DAS-28-CRP and low diffusion capacity (DLCO) were associated with ILD; older age, male sex, smoking status and low DLCO were associated with emphysema. MUC5B was not linked to ILD in this early disease cohort. We built stepwise logistic regression models for ILD and emphysema: after withdrawing interdependent variables, older age, low DLCO and disease activity predicted ILD while smoking predicted emphysema. Genetic results did not improve our models. <bold>Conclusions:</bold> Lung involvement affects a high proportion of patients, especially bronchiolitis, emphysema and ILD. Old age, male sex and lower DLCO were associated ith both ILD and emphysema, suggesting that we should prioritize screening in this population.