Rheumatoid arthritis—clinical features
Rheumatoid arthritis (RA) presents with variable clinical features, making this most frequent chronic systemic autoimmune disease with characteristic joint involvement a diagnostic and therapeutic challenge. This chapter describes in detail the different clinical, laboratory and imaging findings in patients with RA. In addition to the characteristic arthritic involvement, which can lead to severe joint changes with progressive destruction and loss of function, other systemic disease manifestations as well as an increased risk for cardiovascular events and non-Hodgkin's lymphoma with relevance for patients' prognosis are described. Recent approaches to early diagnosis and stratification of patients by predictive factors for a severe course of disease are discussed. These patient profiles include increased inflammatory markers, the presence of autoantibodies, and erosive changes at the time of diagnosis. The novel classification criteria for RA and the significance of autoantibody status, namely seropositivity for antibodies against citrullinated antigens as highly specific diagnostic markers, are highlighted to further promote early differentiation of RA from other arthritic disease entities.