Concerns about risks of HRT - WHI study
July 17, 2002
Recent concerns have been expressed about risks of HRT after the Women's Health Initiative (WHI) study reported increased risks of coronary heart disease, stroke, pulmonary emboli and breast cancer in women taking HRT. The study, reported in the July 17 issue of the Journal of the American Medical Association, (JAMA), was designed to assess the major health benefits and risks of the most commonly used hormone preparation in the United States on healthy, asymptomatic postmenopausal women.
The WHI is a randomised controlled primary prevention trial that was planned to last 8.5 years but the oestrogen/progestogen part of the trial was stopped after 5.2 years because of health safety concerns. In total, 27,000 women were enrolled between 1993 and 1998. 16,608 postmenopausal women aged 50-79 years with an intact uterus were randomised to HRT versus placebo. The combined oestrogen/progestogen used was 0.625mg conjugated equine oestrogen (CEE)and 2.5mg medroxyprogesterone acetate(MPA) daily. Conjugated equine oestrogen only was given to women who had had a hysterectomy, and this part of the trial is being continued, the planned end of this trial being March 2005.
For women taking combined CEE and MPA there was a 29% increased rate of coronary heart disease events, 41% increase in stroke rates, double rates of venous thromboembolism, 26% increase in breast cancer rates, and 22% increase in total cardiovascular disease. Benefits included 37% reduction in colorectal cancer rates, one-third reduction in hip fracture rates and 24% reduction in total fracture rates.
The absolute risk of harm to an individual woman is small. In women taking this CEE/MPA combination, per 10,000 women there were 7 more coronary heart disease events, 8 more strokes, 8 more pulmonary emboli and 8 more breast cancers, with 6 fewer colorectal cancers and 5 fewer hip fractures. Overall, health risks were increased in women taking HRT but the overall rates of deaths and all cancers were not increased with combined HRT.
The study was released early on the JAMA website www.jama.com because of the importance of the findings.
So where are we now?
For several years we have been aware of an association between long term HRT use and increased risk of breast cancer, and of increased risk of venous thromboembolism and HRT use. The increased risk of coronary heart disease and stroke contradicts the findings of some previous studies, though the American Heart Association recently recommended that HRT should not be used for presumed cardiovascular benefit because of uncertainty as to the effect. The type of combined HRT used in the WHI is not currently available in the UK and the findings from this study should not be extrapolated to other HRT products not containing the same components.
HRT does have benefits, particularly for control of menopausal symptoms which can be distressing, and for treatment and prevention of osteoporosis in women who have, or are thought to be at risk of osteoporosis. These are currently seen as the main indications for use of HRT. The CSM noted that the balance of risks and benefits of HRT for its licensed indications remains favourable.
As health professionals, we should help women to balance risks against benefits, individualise type and duration of treatment, and use HRT appropriately with arrangements for adequate review - the risk/benefit analysis should be an ongoing process.
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