The epidemiology of rheumatic diseases.
This review concentrates on certain areas of current interest in the major rheumatic diseases. In rheumatoid arthritis, there is some epidemiologic evidence that the disease is diminishing in incidence and severity. The possible protective effect on rheumatoid arthritis of the oral contraceptive pill has also attracted attention. There is some evidence that it may act by modifying the disease process. Parity may also be a protective factor in rheumatoid arthritis. Recent twin studies have suggested that the monozygotic concordance rate may be lower than previously believed, suggesting that genetic factors may only account for 20% of the disease. In osteoarthritis, new clinical criteria for the hand, knee, and hip have appeared that require further testing. The finding of a specific mutation of one amino acid of a procollagen II gene in family members with premature osteoarthritis has aroused considerable interest. There has been recent debate on the risk of developing ankylosing spondylitis in the population with HLA B27, although most believe this to be less than 7%. Scleroderma is a rare disease that may be increasing in incidence. One study has suggested the clustering of cases around airports. In the majority of countries, osteoporotic fractures appear to have increased at all ages over the last 30 years, although methods of screening using questionnaires or single bone density measurements are unlikely to be useful as widespread public health measures. The question of estrogen use is increasingly being dominated by the large cardiovascular benefit.