The risk reduction for peripheral artery disease, or PAD, was found even though the group of women on HRT were more likely to have conditions such as high cholesterol and high blood pressure, the researchers reported.
"We found that patients who had used HRT were about 20% less likely to have PAD," said study author Dr Caron Rockman, an associate professor of surgery at the NYU Langone Medical Center in New York City.
PAD is a narrowing of the peripheral arteries, usually those in the legs and pelvis. Most often, the symptoms are cramping, pain or tiredness in the leg or hip muscles noticed while walking or climbing stairs. PAD increases the risk of heart attack or stroke.
Risks and benefits of HRT
The risks and benefits of HRT have long been debated. In 2002, results from the large-scale Women's Health Initiative were issued. Those researchers concluded then that the therapy did not protect the heart and the risk-benefit ratio did not favor using it to prevent chronic disease.
More recently, however, the International Menopause Society issued a review stating that HRT remains effective for treating hot flashes and other menopausal symptoms. When individualized, the therapy may have benefit for heart health, those experts said, in women under age 60 when taken short-term.
While previous research has looked at the effect of HRT on PAD, the association is not yet clear, Rockman said. In her study, she looked at a large database of women who underwent vascular screening for PAD.
In all, she evaluated almost 848,000 women; about half reported having used HRT and half had not.
Women who used HRT were more likely to be white, to have smoked cigarettes and to have high blood pressure and high cholesterol. In addition, those on HRT were slightly older (about 64.7 years old on average) than those who were not on HRT (about 64.3 years old).
HRT and heart risks
The investigators also found that those who took HRT were also less likely to have PAD, even with their increased vascular risk factors. While 3.3% of those on HRT had PAD, 4.1% of those not on HRT had it, they reported.
When Rockman controlled for other factors that could have explained the decreased PAD risk, she found that HRT was linked independently with the reduced risk.
The study has limitations, Rockman noted. "We don't know what type of HRT these patients took and for how long," she said. The patients were also self-referred, or women who chose to undergo screening. So something about a self-referred group could have affected the findings.
While the exact mechanism of the link between HRT and reduced risk of PAD isn't known, Rockman said other research has shown that HRT may dilate peripheral blood vessels.
However, the benefit of reducing PAD risk should not at this time be the sole reason for giving HRT, said another expert, Dr John Stevenson, of Imperial College London. He reviewed the study but was not involved in it.
"The finding would be yet another benefit to explain to women contemplating starting HRT for other reasons, and especially if they had a family history of peripheral vascular disease," Stevenson said. "But I think we would need a randomised clinical trial to make prevention of peripheral arterial disease a sole indicator for giving HRT."
Rockman agreed that the pros and cons of HRT need to be put in perspective. "We are certainly not saying that HRT should be given to all to prevent PAD," she said, pointing out that there are potential risks with HRT use.
According to the International Menopause Society review, those who take both oestrogen and progesterone do have a slightly increased risk of breast cancer, for instance. But those who do not have a uterus can expect reduced risks of breast cancer and heart disease if the therapy is short term and individualised, said the experts.
Because Rockman's study was presented at a medical meeting, the data and conclusions should be viewed as preliminary until published in a peer-reviewed journal.
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