Extra-articular manifestations and complications of rheumatoid arthritis

Abstract

Rheumatoid arthritis (RA) is a systemic inflammatory disease that can involve other tissues and organs as well as synovial joints. This chapter reviews the clinical aspects of extra-articular RA, from the early descriptions in rheumatology texts to reports from more recent cross-sectional and inception cohort studies. There is no agreed classification for these manifestations and, because criteria and definitions vary so much, this report includes not only the classic extra-articular features but also the non-articular complications of RA, for example normochromic normocytic anaemia and chronic leg ulcers, and the important disease-associated comorbidities, including non-Hodgkin's lymphoma, ischaemic heart disease and osteoporosis. Incidence and frequency figures for extra-articular RA vary according to study design. Nodules are the most common extra-articular feature, and are present in up to 30%; many of the other classic features occur in 1% or less in normal clinic settings. Sjögren's syndrome, anaemia of chronic disease and pulmonary manifestations are relatively common - in 6-10% - are frequently present in early disease and are all related to worse outcomes measures of rheumatoid disease, in particular functional impairment and mortality. Currently, there are no reliable predictors for these features in early RA, although they are associated with men, smokers, more severe joint disease, worse function, high levels of inflammatory markers, and the presence of rheumatoid factor (RF), antinuclear antibodies (ANA) and the RA HLA-related shared epitope. Many of these manifestations are related to the more active and severe RA, so early and more aggressive RA drug therapies are being employed and, although evidence from randomised studies is not available, this approach would seem appropriate in view of the adverse effect of extra-articular manifestations on RA outcomes. Unfortunately, specific therapies for extra-articular manifestations of RA are largely disappointing or unavailable, except for steroids and cyclophosphamide for vasculitis. The place for biological therapies is still not clear. Pulmonary fibrosis in RA has a poor prognosis whether treated with large doses of steroids, cytotoxic or disease modifying drugs like cyclosporine, or biologics. In summary, extra-articular features and non-articular complications of RA are common and are generally related to worse disease. They need to be recognised early and managed promptly.