RA occurs in ~0.8% of the population; women affected 3 times more often than men; prevalence increases with age, onset most frequent in fourth and fifth decades.

Articular manifestations-typically a symmetric polyarthritis of peripheral joints with pain, tenderness, and swelling of affected joints; morning stiffness is common; PIP and MCP joints frequently involved; joint deformities may develop after persistent inflammation.

Extraarticular manifestations:

• Cutaneous-rheumatoid nodules, vasculitis
• Pulmonary-nodules, interstitial disease, bronchiolitis obliterans-organizing pneumonia (BOOP), pleural disease, Caplan's syndrome [sero (+) RA associated with pneumoconiosis]
• Ocular-keratoconjunctivitis sicca, episcleritis, scleritis
• Hematologic-anemia, Felty's syndrome (splenomegaly and neutropenia)
• Cardiac-pericarditis, myocarditis
• Neurologic-myelopathies secondary to cervical spine disease, entrapment, vasculitis.