Does the route of administration for estrogen hormone therapy impact the risk of venous thromboembolism? Estradiol transdermal system versus oral estrogen-only hormone therapy.

The aim of this retrospective matched-cohort study was to quantify the magnitude of risk reduction for venous thromboembolism (VTE) events with transdermal estradiol therapy system (ETS) compared to oral estrogen-only hormone therapy. A total of 27,018 ETS users were matched with an equal number of oral estrogen-only users. Overall, both unadjusted and adjusted results of this study consistently indicated a significant risk reduction for VTE associated with ETS compared with oral estrogen-only therapy.