SAN ANTONIO — Oral contraceptive use appears to be inversely associated with being rheumatoid-factor positive, Kevin D. Deane, M.D., said in a poster presentation at the annual meeting of the American College of Rheumatology.
In his study, 90% of 256 women had used an oral contraceptive at some time and 10% were positive for rheumatoid factor. The odds ratio of a woman being positive for rheumatoid factor was 0.18 if she had used oral contraceptives.
The women were mothers of children selected as part of an investigation into the heritability of type 1 diabetes. They were chosen for the study because of the likelihood of their having the HLA-DR4 allele, which is associated with both diabetes and rheumatoid arthritis.
Among the other factors examined were breast-feeding; use of nicotine, coffee, and injectable hormones; and age. None of these factors had as strong an association—either positively or negatively—as the use of oral contraception, said Dr. Deane of the University of Colorado, Denver.
The results “are significant statistically,” Dr. Keane said in an interview.
He noted that higher endogenous estrogen levels have been shown to correlate somewhat with a lower incidence of rheumatoid arthritis, and that a decrease in those levels could predispose a woman to vulnerability.
Although Dr. Deane admitted that his findings are merely an intriguing observation, he added that if patients have another reason to take an OC, it's not unreasonable to tell them about the potential for arthritis prevention as an added benefit.