Venous thromboembolism associated with cyproterone acetate in combination with ethinyloestradiol (Dianette): observational studies using the UK General Practice Research Database.

PURPOSE: To derive risk estimates for venous thromboembolism (VTE) in women prescribed cyproterone acetate combined with ethinyloestradiol (CPA/EE), a drug licensed in the UK for the treatment of women with acne or hirsutism. CPA/EE provides a treatment option for women with polycystic ovary syndrome (PCOS). CPA/EE has been associated with an increased risk of VTE.
METHODS: Using the General Practice Research Database, we conducted cohort and case-control analyses in all women aged 15-39 and then nested in a population of women of the same age with acne, hirsutism or PCOS.
RESULTS: The incidence rate ratio (IRR) for VTE in women exposed to CPA/EE versus conventional combined oral contraceptives (COCs) was significantly raised (all women: 1.92; 95% CI: 1.22,2.88; nested: 2.51; 95% CI: 1.07,5.75). Using exposure to conventional COCs as the reference, the adjusted odds ratio (ORadj) for VTE associated with CPA/EE was 1.45 (95% CI: 0.80,2.64) in all women and 1.71 (95% CI: 0.31,9.49) in women with acne, hirsutism or PCOS.
CONCLUSIONS: The risk of VTE associated with CPA/EE use does not differ significantly from that associated with the use of conventional COCs. These data are reassuring and together with knowledge of the risks associated with other treatments for acne, in particular, should influence prescribing practice.