Hormone replacement therapy does not protect post-menopausal women against cardiovascular disease, and may even cause an increased risk of stroke, according to a systematic review of the current evidence.
The Cochrane review looked at the latest evidence on the effects of using hormone therapy for at least six months and involved more than 40,000 women across the world.
The length of time women were took the treatment varied from seven months to just over 10 years.
“The findings of this Cochrane review need to be carefully considered”
Overall, the results showed no evidence that hormone therapy provided any protective effects against death from any cause, and specifically death from cardiovascular disease, non-fatal heart attacks or angina, either in healthy women or women with pre-existing heart disease.
Instead, the findings showed a small increased risk of stroke for post-menopausal women, the study authors said.
They also explored the effect of starting HRT earlier, finding some evidence that women who began treatment within the first 10 years of menopause seemed to have a small protection against death and heart attacks – but the risk of deep vein thrombosis increased.
Review author Dr Henry Boardman, from the department of cardiovascular medicine at Oxford University, said the harms and benefits of hormone therapy varied according to the age of the woman, when they started their treatment.
“The evidence we have provides some support for the so-called ‘timing hypothesis’, but we should bear in mind the size of this effect,” he said.
Dr Boardman said the review suggested that if 1,000 women aged under 60 started HRT, there would be six fewer deaths, eight fewer cases of heart disease and five extra blood clots over seven years, compared to a 1,000 similar women who did not start hormone therapy.
“The findings of this Cochrane review need to be carefully considered,” he said. “This is a complicated health issue, where the same treatment offers benefits in some women, but harms in others.”
“Hormone therapy remains a valid treatment option for women who are significantly troubled by menopausal symptoms, however the risks and benefits of such treatment vary according to age and medical history,” he added.
Maureen Talbot, senior cardiac nurse at the British Heart Foundation, said: “This study supports what we already know and indicates a possible increased risk of stroke or formation of a blood clot in some women.
“It is important that women have a full understanding of the risks and benefits of HRT,” she said.