In a new study involving over 100,000 women of 45 years and above published recently in the journal Hypertension, the researchers said that they have found that the type of oestrogen-based menopausal hormone treatment for women had different impacts on developing high blood pressure.
According to the researchers, swallowing oestrogen in pill form may be related to an increased risk of high blood pressure, when compared to transdermal and vaginal oestrogen.
The study found that when compared to transdermal oestrogen creams, oral oestrogen was associated with a 14% higher risk of high blood pressure and a 19% higher risk of high blood pressure when compared to vaginal oestrogen creams or suppositories.
A woman's body generates less oestrogen and progesterone after menopause, which may increase her risk for cardiovascular disorders such as heart failure say experts of the American Heart Association.
To relieve menopausal symptoms in women, sometimes hormone therapy is prescribed, and according to findings of previous research, some hormone therapies may reduce cardiovascular disease risk in menopausal women under 60 years old or who have had menopause for less than 10 years.
While high blood pressure is a modifiable risk factor for cardiovascular disease, the possible effects of different types of hormone therapy on blood pressure in menopausal women remain unknown, according to the study's authors.
Lead study author Cindy Kalenga, an M.D. & PhD candidate at the University of Calgary in Canada’s Alberta said, “We know oestrogens ingested orally are metabolised through the liver, and this is associated with an increase in factors that can lead to higher blood pressure,” said.
Pointing out that post-menopausal women have an increased risk of high blood pressure when compared to pre-menopausal women, she added, “Furthermore, previous studies have shown that specific types of hormone therapy have been associated with higher rates of heart disease.”
“We chose to dive deeper into factors associated with hormone therapy, such as the route of administration (oral vs. non-oral) and type of oestrogen, and how they may affect blood pressure,” she further added while explaining the rationale of the study.
Involving over 112,000 women, ages 45 years and older, who had requisitioned at least two consecutive prescriptions (a six-month cycle) for oestrogen-only hormone therapy, as identified from health administrative data in Alberta, between 2008 and 2019, the researchers looked for high blood pressure through health records.
First, the researchers looked into the link between the method of oestrogen-only hormone therapy delivery and the likelihood of acquiring high blood pressure at least one year after commencing the treatment.
Hormone therapy was administered in three ways, namely, orally, trans-dermally, and vaginally. Researchers said that they also looked at the oestrogen formulation and the likelihood of developing high blood pressure.
Evaluating the medical records of women who received oestrogen-only hormone therapy for this study, the researchers found that the two most common forms of oestrogen used by study participants were estradiol and conjugated equine oestrogen.
According to the researchers, their analysis revealed that women who used oral oestrogen medication had a 14% higher risk of getting high blood pressure than those who used transdermal oestrogen and a 19% higher risk of developing high blood pressure than those who used vaginal oestrogen creams or suppositories.
Their analysis also showed that conjugated equine oestrogen was related to an 8% greater risk of developing high blood pressure than estradiol.
The scientists found that using oestrogen for longer periods or at a higher dose could increase the risk of high blood pressure.
The study's findings, according to Kalenga, show that if menopausal women undergo hormone therapy, other forms of oestrogen may reduce cardiovascular risks.
“These may include low-dose, non-oral oestrogen, like estradiol, in transdermal or vaginal forms, for the shortest possible period, based on individual symptoms and the risk–benefit ratio, Kalenga said.
Pointing out that these may also be associated with the lowest risk of hypertension, she added, “Of course, this must be balanced with the important benefits of hormone therapy, which include treatment of common menopausal symptoms.”
However noting that their study had several limitations, including that it was based only on medical records and inclusion of oestrogen-only therapy in this study, which is most often prescribed for women who have had their uterus removed surgically, whereas, women with an intact uterus may receive a combination of oestrogen and progestin, another type of hormone.
According to the authors, this suggests that these data should only be considered for women receiving oestrogen-only hormone therapy.
The researchers stated that they would conduct additional research into combined oestrogen and progestin, as well as progestin-only formulations of hormone therapy and their impact on heart and kidney diseases.