rheumatoid arthritis - Rheumatoid arthritis (RA) is a chronic inflammatory and destructive joint disease that affects 0.5–1% of the population in the industrialized world and commonly leads to significant disability and a consequent reduction in quality of life. It is two to three times more frequent in women than in men and can start at any age, with a peak incidence between the fourth and sixth decade of life, RA is associated with high costs and, if not treated appropriately, with a reduction in life expectancy. In addition to the joint swelling and pain caused by the inflammatory process, the ultimate hallmark of RA is joint destruction.