Menopause news

HRT and blood clot risk

2004

A study published in the Journal of the American Medical Association [ref 21] has confirmed the association between use of HRT and increased risk of blood clot (venous thrombosis) and investigates whether other factors contribute to this risk. The report outlines further information from the Women's Health Initiative (WHI) trial and showed that of 16,608 postmenopausal women aged between 50 and 79 years, 167 women who were taking oral oestrogen plus progestogen (combined HRT) developed venous thrombosis (3.5 cases per 1000 women per year) compared to 76 women who took placebo (1.7 cases per 1000 women per year), i.e. the HRT used in this trial conferred an extra 1.8 cases per 1000 women per year. This gives an overall increased risk ratio with HRT of 2.06. When the women were divided further by age and weight, the increased risk with HRT was more apparent for the older age group, particularly for those aged 70 to 79, and for the overweight and obese. Women in the trial were screened for blood clotting factor abnormalities and those who were positive for Factor V Leiden, (a condition which increases the risk of blood clot), had a 6.69-fold increased risk if taking HRT compared to those taking placebo.

Comment

The increased risk of venous thrombosis associated with HRT in this study has previously been reported . As with other reports from the WHI trial, results have to be viewed in context and regard must be given to the fact that women in the WHI trial were generally much older than women who usually take HRT in the UK. It is likely that different types and routes of HRT confer different risk and there is evidence that transdermal HRT may not confer the same increased risk [ref 22]. HRT is well established as a very effective treatment for control of menopausal symptoms and still has a role to play in the prevention/treatment of osteoporosis (treatments of osteoporosis). For all women considering HRT, risks and benefits should be balanced for that individual, taking into account their indication for HRT, past and family history and general health. Older women, those who are overweight or obese, and those with Factor V Leiden, appear to be particularly vulnerable to the increased risk of venous thrombosis with HRT.

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