Update in the epidemiology of the rheumatic diseases.

The epidemiology of early synovitis syndromes in the community remains of interest. Attempts to identify those cases likely to progress to erosive rheumatoid arthritis have yielded some prognostic features that may be clinically applicable. The incidence of juvenile rheumatoid arthritis appears to fluctuate in a cyclic pattern, suggesting microbial or other environmental factors contributing to its occurrence. In the United States, the frequency of scleroderma varies among racial groups with rising rates noted especially among African-American women. A very high prevalence of scleroderma among Oklahoma Choctaws is providing an opportunity to study interactions of environmental and genetic risk factors. Excess weight in middle-aged women and possibly low intake of antioxidants contribute to the progression of established osteoarthritis of the knee.