New research discovers link between high blood pressure and menopausal hormone therapy

A new medical study by the University of Western Sydney has found that hormone therapy used by women to combat the effects of menopause is associated with increased chances of developing high blood pressure, particularly among younger postmenopausal women.

It also found that the longer a woman uses menopausal hormone therapy, the higher her odds of having high blood pressure.

Conducted by the UWS School of Medicine, the research investigated the relationship between the use of menopausal hormone therapy (MHT) and the prevalence of high blood pressure in 43,405 Australian postmenopausal women who were aged 45 years and over.

Data for the research was drawn from the 45 and Up Study – a large scale study of healthy ageing involving over 250,000 men and women in NSW, and the largest study of its kind in the southern hemisphere.

The UWS School of Medicine study was recently published by PLoS ONE, an international peer-reviewed scientific journal by the Public Library of Science.

Key findings from the research reveal:

• 2,536 (20 per cent) of the 12,442 women in the study who had used MHT during their menopause reported having high blood pressure. This compares with 5,149 (17 per cent) of the 30,962 women who had never used MHT and who reported high blood pressure.
• Women who had used MHT were first diagnosed with high blood pressure on average 2.8 years earlier than women who had never used MHT.
• Women who had used MHT for longer time periods had increased odds of high blood pressure, irrespective of when the MHT began relative to menopause, and the number of years since stopping treatment.
• For women in the study who were aged 45-55 years and who had used MHT for longer than ten years, 29 per cent of them were being treated for high blood pressure, compared with 12 per cent of women who had never used menopausal hormone therapy.
• Menopausal hormone therapy users in the 45-55 age group had 1.56 times higher odds of having high blood pressure compared with women of the same age who had never used MHT.
• These odds diminished as women aged. For women aged 71 years or older and who had used MHT for longer than 10 years, there was no difference in the odds of having high blood pressure, compared with women who had never used MHT.

Researcher and senior lecturer in molecular biology and genetics, Dr Joanne Lind from the UWS School of Medicine, says the research findings add an important new dimension to the existing research surrounding the use of menopausal hormone therapy.

She says previous studies looking at the relationship between MHT and cardiovascular health have yielded various, sometimes contradictory, results, with a number of studies advocating the use of MHT in reducing the chances of cardiovascular diseases, while others have shown it to increase risk.

“This is the first study that shows longer use of menopausal hormone therapy is associated with having high blood pressure,” says Dr Lind.

“Even when we took into account potentially contributing factors such as family history and lifestyle – such as physical activity and BMI, history of smoking, drinking alcohol ¬– we still found an association between the use of MHT and having high blood pressure.

“The risk associated with the long-term use of MHT and its impact on a woman’s health, particularly cardiovascular health, has been a common concern among doctors.

“These findings add another piece to the puzzle, and we hope that further research can explore in more detail the causal links between MHT and increased odds of high blood pressure.”

Dr Lind says it is important that high blood pressure is conveyed as a potential health risk for women considering using menopausal hormone therapy.

“Hopefully this research will add to the discussion between women and their physicians. If women have any questions or concerns, it’s advisable to talk to their doctors first.”

A full copy of the journal article can be viewed here.

Ends 

12 July 2012

Contact: Danielle Roddick, Senior Media Officer