Rheumatoid Arthritis Increases in Women, Declines in Men

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Forty years of declining rheumatoid arthritis numbers in women have made an about-face, according to a new Mayo Clinic study. Prevalence of rheumatoid arthritis has increased in women and declined in men, and environmental factors may be to blame.

Rheumatoid arthritis affects 2.1 million people in the United States, and 1 to 3 percent of women can expect to develop the disease during their lifetime, according to the American College of Rheumatology. Women are also three times more likely to have the chronic inflammatory disease, which attacks the joints, significantly affects quality of life, and reduces survival.

The recent upsurge in rheumatoid arthritis incidence in women from 1995 to 2007 was investigated by a research team from the Mayo Clinic, who noted that the rise followed a 40-year period of decline. Under direction of Sherine Gabriel, MD, MSc, the investigators expanded on prior research (1955-1994) and evaluated medical data from 1,761 Minnesota residents age 18 and older who had received one or more diagnoses of arthritis (not including osteoarthritis or degenerative arthritis). The review revealed a diagnosis of rheumatoid arthritis in 466 patients, of whom 321 were females.

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The researchers noted a “modest increase of RA incidence in women during the study period” of 2.5 percent per year, according to Dr. Gabriel. Among men, there was a 0.5 percent decline. Previous research indicates that risks for rheumatoid arthritis include environmental factors such as cigarette smoking, a deficiency of vitamin D, and lower doses of estrogens found in oral contraceptives. The Mayo Clinic researchers speculated that these factors may have a role in the newest rise in the disease in women.

Smoking, for example, has been decreasing in both sexes, but the decline in women has been at a slower pace than in men. The newer oral contraceptives contain lower doses of estrogens than those in older medications, which means women are getting less protection against the development of rheumatoid arthritis.

Vitamin D deficiency has been linked to rheumatoid arthritis in numerous studies. One of the most recent studies published in Environmental Health Perspectives in March 2010 found that women who live in the northern latitudes, which get less sunlight, are more likely to develop rheumatoid arthritis. A Tufts Medical Center study also noted that disorders such as rheumatoid arthritis have been associated “to some extent to vitamin D deficiency.”

The results of the current study showing an increase in rheumatoid arthritis among women and a decline among men need to be examined further to determine the various causative factors. Dr. Gabriel noted that “Reasons for the increase in incidence we found are unknown, but environmental factors likely play a role and should be further explored.”

SOURCES:
American College of Rheumatology
Myasoedova E et al Arthritis & Rheumatology 2010 Feb. 26
Pelajo CF et al. Autoimmunity Reviews 2010 Feb 8
Vieira VM et al. Environmental Health Perspectives 2010 Mar 25

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Comments

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