Specific types of HRT found to raise risk of heart disease and blood clots

WOMEN taking certain types of hormone replacement therapy (HRT) drugs containing both oestrogen and progesterone could be at higher risk of heart disease, a new study has found.

HRT is used to relieve symptoms of menopause, including hot flushes and night sweats – symptoms usually improve after a few days or weeks of taking it.

Previous research has suggested a link between menopausal hormone therapy and an increased risk of cardiovascular disease, but information on the risks of different types has been lacking.

The new study from Sweden, published by the British Medical Journal (BMJ), set out to assess the effect of HRT on the risk of cardiovascular disease according to how it was administered and the combination of hormones.

The researchers analysed data on 920,000 menopausal women from 138 studies and found women taking HRT tablets containing both oestrogen and progesterone were more likely to develop ischemic heart disease and rare but serious blood clots known as venous thromboembolism.

An HRT tablet called tibolone was associated with an increased risk of heart disease, heart attack and stroke.

Lead author Therese Johansson, of Uppsala University, said: “These findings highlight the diverse effects of different hormone combinations and administration methods on the risk of cardiovascular disease.”

The women in the study were aged 50-58 between 2007 and 2020 and had not used hormone therapy in the previous two years.

They excluded women with a history of heart disease, stroke, narrowed arteries, or cancer, and who had undergone surgery to remove their ovaries, a hysterectomy, or sterilisation.

Using monthly prescription records, the women were assigned to one of eight menopausal hormone treatment groups – oral combined continuous (taking oestrogen and progesterone every day without a break), oral combined sequential, oral unopposed oestrogen, oral oestrogen with local progestin, tibolone, transdermal unopposed estrogen, or now menopausal hormone therapy.

Hospital records were then used to track cardiovascular events over two years.

Compared with not starting menopausal hormone therapy, starting oral combined continuous therapy or tibolone was linked to an increased risk of ischemic heart disease.

The increased risk for both types of HRT was shown to be the same as 11 new cases of ischaemic heart disease per 1,000 women who take the drugs over the space of a year.

No increased risk of cardiovascular disease was found for transdermal treatments, which include skin patches, gels and creams.

But an increased risk of blood clots was also found for oral combined continuous, oral combined sequential, oral unopposed oestrogen, and transdermal combined therapy.

The authors wrote: “If 1,000 women started each of these treatments and were observed for a year, we would expect to see seven new cases of venous thromboembolism across all groups.”

Tibolone was linked to an increased risk of stroke and heart attack, but not blood clots.

Benefits and risks of HRT

The benefits of HRT usually outweigh the risks, with recent evidence saying the risks of serious side effects are very low.

The main benefit is symptom relief, but it could also prevent osteoporosis (thinning of the bones) and help maintain muscle strength.

HRT can slightly increase your risk of breast cancer – if you’ve had breast cancer you’ll usually be advised not to take it.

The NHS also advises HRT tablets can increase the risk of blood clots, although the risk is still very low.

And HRT tablets could slightly increase the risk of stroke.

If you’re thinking about taking HRT, speak to your GP who can help you decide.