ABSTRACT
The commonest type of inflammatory arthritis is rheumatoid arthritis, which affects approximately 3% of women and 1% of men in Northern Europe. The prevalence is less in other areas of the world but tends to rise with urbanisation. Patients with rheumatoid arthritis are not seen represented in historical western art and literature. This suggests that it is a modern disease in Europe. However, changes characteristic of the disease are recognised in ancient Native American skeletons, leading to speculation that it originated in the New World. The disease appears to arise from a cell-mediated (T-cell) autoimmune response, but there may be an underlying infectious aetiology. Once the T-cell response is triggered, there is a release of cytokines, including interleukins IL-1 and IL-6, and tumour necrosis factor (TNF), which cause the inflammatory reaction. The disease has a predilection for small joints in the hands and feet and is usually symmetrical. However, it can involve any joint, and also affects tissues elsewhere in the body. There is inflammation of the soft tissues and synovial hyperplasia, containing lymphocytes and plasma cells. A layer of inflammatory tissue called a ‘pannus’ spreads over the joint surfaces and erodes the subchondral bone, denuding articular cartilage. There
is chronic mononuclear cell infiltration and neovascularisation. Rheumatoid factor (RF) is found in approximately 80% of cases of the disease (and in 1-5% of the unaffected population). The extraarticular manifestations are found in the skin, eyes, lungs, heart and kidneys. Amyloid may also arise, as well as neuritis secondary to vasculitis (Summary boxes 37.1 and 37.2).
