Combined hormonal contraceptive (CHC) – chiormadinone acetate/ethinylestradiol Slightly increased risk of venous thromboembolism in women using chlormadinone acetate and ethinylestradiol containing combined hormonal contraceptives.

Summary

• The Retrospective Cohort Study RIVET-RCS concluded that women taking combined hormonal contraceptives containing chlormadinone/ethinylestradiol may have a 1.25-fold increased risk of venous thromboembolism (VTE) compared to those taking levonorgestrel. Based on these results, the annual risk of VTE in women taking chlormadinone acetate with ethinylestradiol is estimated at 6-9 VTE cases per 10,000 women.
• This compares to an annual incidence of 5-7 VTE cases in 10,000 women who are using low risk combined hormonal contraceptives that contain levonorgestrel, norethisterone, or norgestimate, and to 2 VTE cases per 10,000 women who are not using a combined hormonal contraceptive.
• In most women, the benefits of using a combined hormonal contraceptive will outweigh the risk of serious side effects. However, the decision to prescribe a combined hormonal contraceptive should take into consideration the individual woman’s current risk factors, particularly those for VTE, and how the risk of VTE compares with other combined hormonal contraceptives. The risk is highest during the first year of using any combined hormonal contraceptive or upon re-starting combined hormonal contraceptives after a break of 4 or more weeks.
• Prescribers should raise awareness of the signs and symptoms of VTE and arterial thromboembolism (ATE), which should be described to women when a combined hormonal contraceptive is prescribed and should regularly reassess individual risk factors. Prescribers are reminded that a significant proportion of thromboembolisms are not preceded by any obvious signs or symptoms.