20 February, 2017:
One of the main issues discussed in relation to postmenopausal hormone therapy (HT) is the risk for venous thromboembolic (VTE) events. In fact, this safety aspect of HT use is probably the only significant one in healthy women younger than 60 or during the first decade of use. A history of VTE usually deters physicians from prescribing HT as these women have anyway a higher risk for recurrent VTE in the future. Is this true also for women who were already using HT when the index VTE occurred?
Kiconco and colleagues investigated the outcomes in women whose initial VTE event was hormone-related and compared them to women whose initial event had no obvious cause . Their cohort utilized the Clinical Practice Research Datalink linked to Hospital Episode Statistics data from England. The investigators selected 4170 women aged between 15 and 64 years who were diagnosed with a first VTE event between 1997 and 2011, and treated for a while with anticoagulants, which were then discontinued. The median follow-up time after stopping anticoagulation was around 2 years. Recurrent VTE events were higher in non-users than in users of hormones (15.3% vs. 9.5%; 51 cases per 1000 vs. 37 cases per 1000). Further to the significant difference in the absolute number of events in each subgroup, hormone users had 29% lower recurrence risk than non-users (adjusted HR = 0.71; 95% CI 0.58–0.88), a relationship which existed both in women aged 15–44 years (predominantly oral contraceptive users) and those aged 45–64 years (predominantly HT users). The conclusion was that having a hormone-associated VTE was associated with a lower recurrence risk than that related to unprovoked VTE after cessation of both the hormone-containing preparation and the subsequent anticoagulation. Furthermore, if this is the case, then prolonged anticoagulation may be unjustified in such women.