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Rheumatoid Arthritis: Overview and Risk Factors

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disease marked by inflammation of the joints, sometimes with prominent extra-articular manifestations. The disease is initially characterized by inflammation of the synovial membranes (synovitis) of peripheral joints. If RA is uncontrolled, many cases ultimately lead to destruction of the articular cartilage, bone erosions, and significant deformity, disability, and morbidity in 10 to 20 years from onset.

The etiology of rheumatoid arthritis is unknown, but likely involves interaction of genetic and environmental factors. The typical presentation consists of a gradual onset of polyarticular symmetric arthritis of the small joints, characterized by pain, morning stiffness, and joint swelling. Among the early articular sites of disease are the metacarpophalangeal and proximal interphalangeal joints of the fingers, the metacarpophalangeal and interphalangeal joints of the thumbs, the wrists, and the metatarsophalangeal joints of the toes. Extra-articular manifestations may include dry eye syndrome (which occurs with variable severity in up to 50% of patients), pericarditis, episcleritis, scleritis, subcutaneous nodules, vasculitis, splenomegaly, fatigue, mild anemia, and elevation of the inflammatory markers erythrocyte sedimentation rate and C-reactive protein (CRP).

Risk Factors

RA affects about 1% of the adult population in the United States. Prevalence varies widely among ethnic and regional groups. For example, far less than 1% of rural Africans are affected, compared with 5% of Pima Indians. Other risk factors include:

Age. The typical age of onset is 30 to 55 years, although the disease may occur at any age.

Gender. RA is 2 to 3 times more common in women than in men.

Genetics. The HLA-DRB1 gene contains a short disease-conferring sequence.


Rheumatoid Arthritis: Diagnosis and Treatment >>