Women’s Health Initiative – estrogen plus progestin three-year follow up: Women’s Health Concern’s statement on the results

The Women’s Health Initiative (WHI) in the USA was a series of clinical trials involving thousands of women, one of which compared the effects of HRT against placebo (dummy treatment). The preliminary results from the oestrogen-progestogen HRT arm were published in 2002 after the study had been stopped, claiming that HRT caused an increase in heart attack, stroke, blood clots and breast cancer.

Widespread alarm because of these findings caused almost half of UK HRT users to abandon the treatment. But subsequent, more detailed analyses showed that most of these concerns were not justified.

Benefits were seen for women starting on HRT below the age of 60 or within 10 years of menopause and risks were minimal, but in the elderly women starting on HRT such benefits were not seen.

Results of a three-year observational follow-up

Now the WHI investigators have just presented the findings of a three-year follow-up of the women who had previously taken part in the trial.

Comparisons were made between those who had previously taken HRT and those who had taken the placebo. The preliminary results are again being presented as showing adverse effects in the previous HRT users, even when the differences from the previous placebo users are not statistically significant (such differences could have arisen by chance rather than due to any previous treatment effects). In fact, the only significant difference between the two groups of women during the follow-up period is a higher incidence of all cancers in the previous HRT users. This is not due to a difference in breast cancer between the groups, but appears to be due to an increase in a whole variety of cancers. It is unconvincing, and has probably arisen by chance.

Again, it is difficult to draw any firm conclusions from these new results, as they have not been fully analysed. Thus, the age effect, which was so important in the clinical trial findings, has not been taken into account – nor is any information given as to what subsequent therapies the women might have taken, which could influence their health during the follow-up.

The vast majority of postmenopausal women in the UK that start on HRT do so within 10 years of their menopause. For these women, HRT will bring more benefits than risks, they can be reassured that this remains the case, and can continue on the treatment under the supervision of their GP should they wish to do so.

This new information should not alter the position for HRT use in the UK.

John C Stevenson MB BS, FRCP, FESC, MFSEM

Chairman of Women’s Health Concern and Member of the Women’s Health Concern Medical Advisory Panel

If you have renewed concerns about HRT, please do consult your GP. 

You can also ring our

Telephone advisory service.

See our leaflet entitled ‘HRT – What you should know about the risks and benefits’ in the WHC factsheets and other helpful resources section.

A more detailed scientific statement regarding the three-year observational follow up to the WHI clinical trial can be seen on the British Menopause Society’s website:

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2016-11-19T10:05:18+00:005 March 2008|