(HealthDay News) – For women with polycystic ovary syndrome (PCOS), the risk of venous thromboembolism is increased for non-users of oral contraceptives, and further increased for users of combined oral contraceptives, according to a study published online Dec. 3 in CMAJ, the journal of the Canadian Medical Association.

Steven T. Bird, PharmD, from the U.S. Food and Drug Administration in Silver Spring, MD, and colleagues developed a population-based cohort from the IMS LifeLink Health Plan Claims Database, including 43,506 women aged 18–46 years taking combined oral contraceptives who had a claim for PCOS. These cases were propensity-score matched to the same number of controls taking oral contraceptives.

The researchers found that the incidence of venous thromboembolism was 23.7 per 10,000 person-years for women with PCOS using combined oral contraceptives, compared with 10.9 per 10,000 person-years for controls, representing a relative risk of 2.14 for venous thromboembolism. For women with PCOS not taking oral contraceptives, the risk of venous thromboembolism was 6.3 per 10,000 person-years, compared with an incidence of 4.1 per 10,000 person-years for matched controls, representing a relative risk of 1.55 for women with PCOS not taking oral contraceptives.

“Physicians should be aware of a potentially synergistic increase in venous thromboembolism risk in women with PCOS taking combined oral contraceptives,” the authors write.

One author disclosed financial ties to Pfizer and the Observational Medical Outcomes Partnership.

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