HRT : oral estrogen and norpregnanes derivatives, a thrombogenic risk

Estrogen orally and norpregnanes derived progestins used in hormone replacement therapy ( HRT) is associated with a fourfold increase in the risk of venous thromboembolism in postmenopausal women , confirm the results of the French ESTHER study , published in the journal " circulation " .
Results of this study on the risk of thromboembolism depending on the route of estrogen administration had already been published and the results on the same risk depending on the type of progestin used were submitted to European Days of the French Society of Cardiology ( SFC ) .

These data , however, had not changed the recommendations of the French Agency for the Safety of Health Products (AFSSAPS ) at its focus.

The published results concerning the first 271 consecutive cases of venous thromboembolism in postmenopausal women 45 to 70 years and 610 matched controls based on the establishment where they were treated , age and date of admission.

The study confirms the risk of venous thromboembolism multiplied by 4.2 in users of oral estrogen compared with non-users of hormone replacement therapy (HRT ), while the risk to users of the transdermally is not increased compared to non-users.

It also shows a 3.9 -fold increase in the risk of venous thromboembolism when norpregnanes derivatives are associated with estrogen , compared with non-users of HRT , while the risk is not increased with micronized progesterone or with the pregnane derivative .

In this study, 26.0 % and 29.9% of controls used transdermal estrogen and 17.4 % and 6.5% of controls used oral estrogens.

In addition, only 5.5 % and 6.7% of controls were treated with estrogen alone . 7.4 % and 10.4% of controls using micronized progesterone , 15.1 % and 13.1% of the controls pregnanes and 15.5 % and 6.1% of the controls norpregnanes derivatives .

"Our data highlight the importance of the route of administration of estrogen and progestin choice in determining the risk-benefit profile of hormone therapy ," the authors conclude.

They suggest that the effect of transdermal estrogen associated with different types of progestins on health is studied in randomized trials . They point out that their study is observational and can therefore be biased .