Researchers have found a link between women who have taken oral contraceptives and an increased risk of multiple sclerosis (MS). However, this does not mean women should stop taking birth control.
Kerstin Hellwig, MD, and colleagues used membership data from Kaiser Permanente Southern California and looked at electronic medical records of 305 women aged 14 to 48 years who were diagnosed with MS or its precursor, clinically isolated syndrome (CIS), between 2008 and 2011, and compared the results with 3,050 matched controls. Approximately 30% of the cases and nearly 24% of the controls had taken oral contraceptives for 3 months or more within the last 3 years before MS onset. Most of the patients used estrogen/progestin combination drugs.
Her study results will be presented on April 30 during the American Academy of Neurology 2014 Annual Meeting in Philadelphia, Penn.
“We then investigated the exposure-use of oral contraceptives-through a linkage with the pharmacy records. Every case was then matched with 10 controls, on age, race/ethnicity, and membership characteristics,” said Dr. Hellwig, post-doctoral research fellow, Kaiser Permanente Southern California, Department of Research & Evaluation. “We took into account confounders such as smoking and parity in the three years prior to diagnosis and adjusted for these factors in our statistical model.”
“This study clearly establishes a link between the use of oral contraceptives in the three years prior to symptom onset and developing the first symptom of MS that cannot be explained by other factors that could influence the choice to use oral contraceptive pills like age, pregnancies, smoking, and obesity,” she said. “But the overall effect is relatively small-only 30% increased risk-and we did not measure other factors associated with the lifestyle of a modern woman that might also be able to explain the results. Our overall results show that the use of oral contraceptives may partly explain the rising incidence of MS in women-among others such as obesity and smoking.”
Thus, the results should be viewed with caution and require replication, Dr. Hellwig said. “The findings from this study do not warrant any change in oral contraceptive prescribing practices. We do not recommend that women stop using oral contraceptives because women who take oral contraceptives do not know if they will develop MS or not, later in life. After all, MS is a rare disease and only about every 1,000th person will develop MS.”