This is a prospective multicenter study in southern Belgium to determine the prevalence and incidence of interstitial lung disease in patients with rheumatoid arthritis (RA).

This is a prospective multi-centric longitudinal study of the prevalence and incidence of pulmonary diseases in patients with RA.

During one year, patients with a RA diagnosis (according to the criteria of the American Society of Rheumatology) in the south of Belgium will be enrolled on a voluntary basis. If available, data including quality of life and symptoms questionnaires, medical examinations, 6-minute walk-tests, pulmonary function tests and chest CT will be collected during two years.

Furthermore, patients could be included (if available data) in two additional sub-cohorts:

• "RAIDbio" sub-cohort studying biomarkers: volatile organic compounds, induced sputum and blood biomarkers;
• "RAIDomix" sub-cohort studying radiomic patterns (based on high resolution computed tomography of the chest).

Due to a non-specific and poor clinical expression at beginning, there is currently an under-diagnosis of rheumatoid arthritis associated-interstitial lung disease (RA-ILD) at an early stage and we assume that an annual pneumological follow-up, search of early biomarkers and a radiomic approach of RA patients will overcome this issue. This should lead to a better follow-up and management (including the use of anti-fibrotic therapies in the future) of these patients and ultimately to a decrease in morbidity and mortality.

Inclusion Criteria:

• Diagnosis of rheumatoid arthritis according to the criteria of the American Society of Rheumatology
• Age > 18 years
• Willing to participate in the study and sign the informed consent form (ICF) of participants or their legal authorized representative
• RAIDbio subcohort : available data for one of the following analysis of biomarkers: volatile organic compounds, induced sputum or blood markers
• RAIDomix : available data for high resolution computed tomography of the chest

Exclusion Criteria: none

Patients with rheumatoid arthritis visiting their rheumatologist in South of Belgium and willing to participate