Absolute and attributable risk of venous thromboembolism in women on combined cyproterone acetate and ethinylestradiol.

OBJECTIVE

To achieve absolute risk estimates of venous thromboembolism (VTE) among women on cyproterone acetate plus ethinylestradiol (CPA/EE), and among women on combined oral contraceptives (COCs).

METHODS

From the Danish National Register of Patients (NRP), 1996 to 1998, the records of 1.1 million Danish women, ages 15 to 44 years, were searched for evidence of VTE. COC use was ascertained through mailed questionnaires. Sales statistics of COCs and CPA/EE were provided through Danish Drug Statistics.

RESULTS

During the time frame of the study, 330 women were found to have had VTE while on COCs. Of these women, 67 were on levonorgestrel-containing COCs. Eleven were on CPA/EE. The corresponding absolute risk of VTE was 3.4 (range, 3.1-3.8) per 10 000 women years among the women on COCs, 4.2 (range, 3.2-5.2) per 10 000 women years among women on levonorgestrel-containing COCs, and 3.1 (range, 1.3-4.9) per 10 000 women years among the women on CPA/EE.

CONCLUSION

Our results suggest the absolute risk of VTE among Danish women on COCs is similar to that among women taking CPA/EE.