Research Activities, September 2013
Women with polycystic ovary syndrome taking combined oral contraceptives have greater risk of blood clots
Polycystic ovary syndrome (PCOS) affects as many as 15 percent of women of reproductive age. Treatment consists of combination oral contraceptive therapy. Oral contraceptives, however, are known to increase the risk for blood clot (venous thromboembolism) and cardiovascular disease in women without PCOS. A recent study found a twofold increased risk of blood clots in women with PCOS taking combined oral contraceptives compared to women without PCOS taking combined oral contraceptives. Even women with PCOS not taking oral contraceptives still had a 1.5-fold increased risk of venous thromboembolism compared to women without PCOS.
Using managed care claims, the researchers identified 43,506 women with PCOS aged 18 to 46. All were taking combined oral contraceptives. This group was matched to a second group of 43,506 women without PCOS who were taking combined oral contraceptives and had similar baseline coexisting conditions. Another random sample of 2 million women not taking combined oral contraceptives was used to determine the risk for blood clots among women with PCOS who were not using combined oral contraceptives.
The incidence of venous thromboembolism in women with PCOS taking combined oral contraceptives was 23.7 per 10,000 person-years. Among the matched control women taking combined oral contraceptives but without PCOS, the incidence was 10.9 per 10,000 person-years. This amounts to a twofold increased risk in women with PCOS being treated with oral contraceptive therapy. The incidence was 6.3 per 10,000 person-years in women with PCOS not taking oral contraceptives.
The researchers suggest that physicians be vigilant about the increased risk for venous thromboembolism in women with PCOS taking combined oral contraceptives. The study was supported in part by AHRQ (HS19516).
See "Risk of venous thromboembolism in women with polycystic ovary syndrome: A population-based matched cohort analysis," by Steven T. Bird, Pharm.D., M.S., Abraham G. Hartzema, Ph.D., Pharm.D., James M. Brophy, Ph.D., M.D., and others in the February 5, 2013, Canadian Medical Association Journal 185(2), pp. E115-E120.