Comparing VTE risks of various hormone formulations

Women who use oral contraceptives (OC) or hormone replacement therapy (HRT) have a two- to sixfold increased risk of a venous thromboembolic event (VTE) compared with nonusers, according to a recent review of available data. Users of OCs containing desogestrel or gestodene, as opposed to levonorgestrel, are at slightly higher risk. And users of OCs or HRT who carry an inherited hypercoaguable state are at exponentially higher risk.

Of the combination OCs, those containing 35 µg or less of ethinyl estradiol and a second-generation progestin are associated with the lowest risk of VTEs. But the safest option, in terms of lowest risk of VTE, may be progestin-only contraceptives and transdermal HRT.

Interestingly, the true VTE risk associated with norethindrone and norgestimate-among the most commonly used progestins in the US-is essentially unknown.