Objective: Osteoarthritis (OA) is the most common type of arthritis; involvement of joints in the hand is highly prevalent, especially in the elderly. Few data are available on the incidence of hand OA in men and women or on the association between OA in one hand joint with incidence in others.
Methods: We studied the cumulative incidence of radiographic hand OA in a population based group of men and women, and evaluated whether baseline OA in one joint affected OA rates in other joints in the hand. Study subjects were 751 members of the Framingham Study cohort, who had a baseline right hand radiograph taken in 1967-1969 (mean age 55+/-5.58) and followup radiographs 24 years later.
Results: In those without OA at baseline, women had more incident disease than men in almost all hand joints, but the joints most frequently affected were the same in both sexes: the distal interphalangeal (DIP), followed by the base of the thumb, proximal interphalangeal (PIP), and metacarpophalangeal (MCP) joints. The MCP joint group was the only one in which the incidence in men was comparable to incidence in women. Prevalent OA in one or more joints in a row (e.g., MCP) markedly increased the risk of incident OA in other joints in the same row. Also, prevalent OA in one joint in a finger (a ray) increased the risk of incident OA in other joints in that ray. Prevalent OA in either DIP or PIP joints at baseline substantially increased the risk of incident OA in all other hand joints. Thumb base OA at baseline increased risk in MCP joints, and to a lesser extent, DIP and PIP joints.
Conclusion: Cumulative incidence was generally higher in women than men, baseline OA in one joint in a row markedly increased the risk of developing OA in other joints in the same row, and baseline OA in a joint in a ray similarly increased risk in that ray. Interphalangeal joint OA at baseline appeared to increase subsequent OA in all hand joints, baseline OA in the thumb was not as strong a predictor. This descriptive information on incidence of radiographic hand OA should generate new hypotheses about why OA affects hands in particular patterns.