'No risk of blood clots' from HRT patches
Publication Date:23/05/2008
Using hormone replacement therapy (HRT) in the form of skin patches does not seem to increase the risk of blood clots, unlike HRT tablets, according to a large review of the research.
What do we know already?
HRT is used to reduce symptoms of the menopause, such as hot flushes, night sweats and vaginal dryness. It contains the hormone oestrogen, either alone or combined with another hormone called progestogen. The production of these hormones slows down as women reach the menopause.
There’s been lots of research on HRT, and you’ve probably read about some of this. Although it has benefits, HRT has been linked with some important risks. It increases the risk of breast cancer, and may also increase the risk of heart disease and stroke.
Previous research has also linked HRT with an increased risk of blood clots in the veins, called deep vein thrombosis or DVT. If one these blood clots breaks away and blocks blood flow in the lungs, it can be fatal.
For most women, these increased risks are small, but they are important to know about if you are taking HRT, or are considering taking it.
This is first time researchers have looked at whether HRT tablets and patches carry different risks of blood clots.
What does the new study say?
The new study found that women who take HRT tablets were between two and three times more likely to have a blood clot than those who didn’t use HRT. The risk was highest in the first year of taking HRT. It was also much higher for women who were very overweight (obese), and for those who had a problem with blood clotting to start with.
The researchers calculated that an extra one to two women out of 1,000 will get a blood clot each year because of taking HRT tablets.
Women who used HRT patches, or who had taken HRT in the past, were no more likely to get blood clots than women who didn’t take HRT.
Tell me more about the study’s findings
The study also found that it doesn’t seem to matter what kind of HRT tablets you take. Taking oestrogen and progestogen together has the same risk of blood clots as taking oestrogen on its own.
The researchers say that the difference between HRT tablets and patches may be due to the way oestrogen is absorbed into the blood. Tablets enter the digestive system and are processed by the liver, and this might upset the balance of chemicals in the blood that are responsible for clotting.
Where does the study come from?
The study was done by researchers from universities in Paris and the Royal Infirmary in Glasgow. It was published in the British Medical Journal (BMJ).
How reliable are the findings?
This was a good study. However, there was far more research on HRT tablets than patches. Out of 17 studies altogether, only four looked at the effect of patches. And the studies on patches were not the best type of studies.
The researchers say that the findings from this study on patches need to confirmed in better-quality studies. More studies are also needed to look at whether the different types of oestrogens and progestogens used in HRT differ in their effect on the risk of blood clots.
What does this mean for me?
If you’re taking HRT or considering it, this study has important findings for you. It suggests that, if you take HRT as patches rather than tablets, there is no additional risk of blood clots. The risk of blood clots from HRT tablets is greatest in women who are very overweight (obese) or who have inherited genes that make the blood more prone to clotting. These women in particular should avoid HRT tablets, say the researchers.
What should I do now? Blood clots are just one of the risks linked with taking HRT, and if you’re taking or considering taking HRT, you need to be aware of all the possible benefits and risks of this treatment. Bear in mind that, for other risks, we still don't know if there is any difference between HRT patches and tablets.
While HRT can reduce the symptoms of the menopause, it also slightly increases your chances of having a stroke and of getting breast cancer. If you are 60 or older it also increases the risk of heart disease. For most women, the risks are small, but you need to discuss them with your doctor before starting treatment.
The government's Committee on Safety of Medicines says that HRT is helpful for treating symptoms of the menopause, but that women should take the lowest dose that works for them for the shortest amount of time. When you talk to you doctor you may also like to discuss whether it’s better for you to take HRT as patches.
If you're taking HRT, you should review your treatment with your doctor every year.
From:
Canonico M, Plu-Bureau G, Lowe, professor GDO, et al. Hormone replacement therapy and risk of venous thromboembolism in postmenopausal women: systematic review and meta-analysis. Online first at www.bmj.com
To learn more about the menopause and how it is treated, see our information on the menopause.
News Archive
© BMJ Publishing Group Limited ("BMJ Group") 2007. All rights reserved
This information does not replace medical advice. If you are concerned you might have a medical problem please ask your Boots pharmacy team in your local Boots store, or see your doctor.
