Hormonal contraception and venous thromboembolism.

BACKGROUND

New studies about the influence of hormonal contraception on the risk of venous thromboembolism (VTE) have been published.

AIM: To evaluate new epidemiological data and to propose clinical consequences.

DESIGN

A literature survey.

METHODS

Studies assessing the risk of specific types of hormonal contraception were evaluated, compared and set into a clinical perspective.

RESULTS

The majority of newer studies have demonstrated a threefold increased risk of VTE in current users of medium- and low-dose combined oral contraceptives (COCs) with norethisterone, levonorgestrel (LNG) or norgestimate compared with non-users. The same studies have demonstrated a sixfold increased risk of VTE in users of combined pills with desogestrel, gestodene, drospirenone or cyproteroneacetate, and in users of the contraceptive vaginal ring, compared with non-users. The rate ratio of VTE between users of COCs with newer progestogens compared with users of COCs with LNG was 1.5-2.8 in seven studies and 1.0 in two studies. Progestogen-only contraception did not confer an increased risk of VTE in any study. The incidence rate of VTE in non-pregnant women aged 15-49 years using non-hormonal contraception is three per 10 000 years.

CONCLUSIONS

For women starting on hormonal contraception, we recommend medium- or low-dose combined pills with norethisterone, LNG or norgestimate as first-choice preparations. For the many women who are users of COCs with newer progestogens, although the absolute risk of VTE is low, a change to combined pills with norethisterone, LNG or norgestimate may halve their risk of VTE. Finally, we recommend COCs with 20 μg estrogen combined with the older progestogens to be launched in the Scandinavian countries. Women at an increased risk of VTE should consider progestogen-only contraception or non-hormonal contraception.