Washington, May 27 (ANI): A newly published study by researchers from the Mayo Clinic has shown that the incidence of rheumatoid arthritis (RA) in women has risen during the period of 1995 to 2007.
This rise in RA follows a 4-decade period of decline and study authors speculate environmental factors such as cigarette smoking, vitamin D deficiency, and lower dose synthetic estrogens in oral contraceptives may be the source of the increase.
Details of the study which includes more than 50 years of RA epidemiology data appear in the June issue of Arthritis and Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology.
The study, led by Sherine Gabriel, expanded on prior research (1955-1994) from the Mayo Clinic team, by determining RA incidence and prevalence between 1995 and 2007.
Researchers screened medical record of 1,761 Olmsted County, Minnesota residents 18 years and older who had received 1 or more diagnoses of arthritis (excluding degenerative arthritis or osteoarthritis). After thorough review of all medical records, a diagnosis of RA was made in 466 patients whose mean age at RA incidence was 55.6 years, with 321 females (69 percent) in the study cohort.
"We observed a modest increase of RA incidence in women during the study period, which followed a sharp decline in incidence during the previous 4 decades," said Dr. Gabriel.
Results show that RA incidence in women increased by 2.5 percent per year from 1995 to 2007, while a decrease of 0.5 percent was noted for men. Researchers did not find a disproportionate increase in RA incidence in any particular age group over the study period.
"As expected we found an increase in RA prevalence during the same time period," added Dr. Gabriel.
The overall age- and sex-adjusted prevalence of RA increased from 0.62 percent in 1995 to 0.72 percent in 2005.
Dr. Gabriel said: "Reasons for the increase in incidence we found are unknown, but environmental factors likely play a role and should be further explored." (ANI)