Hormones are believed to play a part in the autoimmune disease systemic lupus erythematosus (SLE) because the women to men with it is nine to one, and the incidence increases after puberty.
A new large, population-based observational study found that the use of oral contraceptives was associated with an increased risk of SLE, particularly among women who recently started taking them. The study was published in the April issue of Arthritis Care & Research (http://www3.interscience.wiley.com/journal/77005015/home).
Dr. Samy Suissa of the Centre for Clinical Epidemiology at Jewish General Hospital of McGill University in Montreal led the researchers who obtained data on more than 1.7 million women ages 18-45 from the U.K. General Practice Research Database. The women all had prescriptions for combined oral contraceptives (COCs) containing estrogen and progestogen.
During an average of eight years of follow-up, 786 women had a first-time diagnosis of SLE. Each case was matched with up to 10 controls among women without SLE at the time of the case's diagnosis.
The results showed that the use of COCs was associated with a significant increased risk of newly diagnosed SLE.
Previous studies on the risk of SLE following use of oral contraceptives had conflicting results, but the results of this study are consistent and complement those of the NIH-sponsored Nurses' Health Study.
"Our findings that longer-term use of contraceptives is associated with an increased risk of incident SLE (albeit of lower magnitude) and that current use of contraceptives with higher doses of ethinyl estradiol is associated with an increased risk of incident SLE, suggest a possible dose-response effect of estrogen on SLE onset, which could be an alternative or additional mechanism to favor occurrence of the disease," the authors state. They note that the absence of significant increased risk in third-generation contraceptives may be related to the lower doses of estrogen compared to earlier generations.
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