Extra-articular rheumatoid arthritis: example of RA-associated interstitial lung disease.

Rheumatoid arthritis (RA) is a systemic autoimmune disease that primarily affects the joints. However, extra-articular manifestations are common and can be serious. These include cutaneous rheumatoid nodules, Sjögren's disease, vasculitis, Felty syndrome, and pulmonary manifestations such as interstitial lung disease (ILD), bronchiectasis, obliterative bronchiolitis, nodules, and pleural effusions. The prevalence of most extra-articular RA manifestations has decreased over the past few decades with expanded treatment options, with the notable exception of RA-ILD. Clinically apparent RA-ILD affects about 10% of people with RA and is characterised by pulmonary fibrosis and/or inflammation. RA-ILD is associated with high morbidity and mortality. Since screening for ILD is not routinely performed, an additional 10% to 30% of people with RA may have subclinical ILD characterised by chest imaging abnormalities without symptoms that do not reach clinical attention. Research efforts are ongoing to identify risk factors and optimise screening strategies to identify early RA-ILD. Biomarkers for RA-ILD risk and progression may inform pathogenesis and prevention strategies. Treatment of active RA with anti-inflammatory medications may also treat ILD. Several antifibrotics may also slow the progression of ILD. However, more trials are needed to optimise the treatment of RA-ILD and improve outcomes.