Hormone replacement therapy should not be prescribed to older women who are many years past menopause because it likely to increase rather than reduce their risk of heart disease, experts say in the online version of this week’s British Medical Journal.

Significantly, however, the authors support the view that HRT is a safe, short-term treatment for younger women in early menopause to relieve symptoms and improve quality of life.

In 2002, the Women’s Health Initiative trial found that postmenopausal women taking HRT had more heart attacks and strokes than non-HRT users. The trial was halted early and millions of women around the world stopped taking HRT. But scientists now believe that these risks may only apply to older women who do not normally use HRT.

In 1999, another trial (WISDOM) began to assess the long-term risks and benefits of HRT after the menopause. This trial was stopped prematurely after the first WHI results appeared. But some findings that did emerge from the WISDOM study are published today, and provide new insights about HRT when it is initiated in older postmenopausal women.

Received WISDOM

The WISDOM team studied 5,692 healthy women registered at general practices in the UK, Australia and New Zealand with an average age of 63 years, 15 years after the menopause. Women received either a daily dose of combined hormone therapy (oestrogen and progestogen) or a placebo pill. Those who had had a hysterectomy were split between combined hormone treatment, oestrogen only and a placebo. All women were monitored for an average of 12 months and main outcomes such as cardiovascular disease, osteoporotic fractures, breast cancer and deaths, were recorded.

There was a significant increase in the number of major cardiovascular events (angina, heart attack or sudden coronary death) and blood clots (venous thromboembolisms) in the combined hormone therapy group compared to the placebo group. Rates for cerebrovascular disease, breast or other cancers, fractures and overall deaths were not significantly different in these two groups.

Nonetheless, the results found no overall disease prevention benefit, and some potential risk, for women who start hormone replacement therapy many years after menopause. However, the authors stress that these results cannot necessarily be applied to younger menopausal women starting hormone replacement therapy to relieve symptoms such as hot flushes and night sweats. For these women, recent studies suggest there may even be cardiovascular benefits of taking HRT around the time of menopause.

In order to assess conclusively the long-term benefits and risks among these women, lead researcher Professor Alastair MacLennan of the Women’s and Children’s Hospital, Adelaide, said that a long term, randomised, placebo-controlled trial of hormone replacement therapy from menopause was still needed. But she said this presented “great problems in terms of funding, compliance, and continuance, especially in symptomatic women”.

In an accompanying editorial, Dr Helen Roberts at the University of Auckland said HRT had now “come full circle” with the evidence suggesting that its use be limited to the short-term relief of symptoms such as hot flushes, night sweats. She said: “Healthy women in early menopause are unlikely to face substantially increased risks when using hormones for a few years." However, she agreed that long-term use of HRT should not recommended.