The benefits and risks of hormone replacement therapy (HRT- usually a combination of estrogens and progestins) in menopausal women continue to be a subject of debate because of lack of conclusive evidence in many areas. The subject has recently been reviewed (October 1999) by Dr. Sally McNagny, on which our summary is based.

The evidence is classified as “Strong” if it is based on randomized controlled clinical trials, which are the most conclusive way of showing if a treatment works or not. It is classified as “Inconclusive” if it is based on observational studies, where we cannot be certain if the treatment is itself responsible for the observed benefit. An example of this is the finding that women who take estrogens tend to have less heart disease than those who don’t, but they also tend to have a healthier lifestyle, so we can’t be sure that it’s the estrogens which are responsible for the lower rate of heart disease. “No effect” means that there is good evidence that the condition is unaffected by HRT one way or the other.

Prevention of hot flashes Evidence Strong

HRT produces a 70% reduction of hot flashes, which commonly occur at the time of the menopause, but is usually not needed for more than five years.

Prevention of osteoporosis Evidence Strong

HRT reduces the rate of vertebral bone fractures by about 60%.

Prevention of hip fracture Evidence Inconclusive

Observational studies suggest that women using HRT have a 25% lower risk of hip fracture.

Improvement in blood lipids Evidence Strong

Several studies have shown that HRT lowers LDL (Bad) cholesterol and triglycerides by about 10%, and rises HDL (good) cholesterol by 10%, but these effects are smaller after three years or so. The effects on HDL are less if combined estrogen and progestin treatment are sued.

Prevention of heart disease Evidence Inconclusive

Although women who use HRT tend to have less heart disease, so far no randomized trial has reported on whether or not it is the HRT that is responsible.

Prevention of a second heart attack No Effect

The only randomized trial of HRT in women with known heart disease (called HERS) found no evidence for protection from a second heart attack. HRT is therefore not currently recommended for preventing heart disease.

High blood pressure No Effect

Several studies have found that in general HRT does not affect blood pressure.

Risk of deep vein thrombosis or pulmonary embolism Evidence Strong

HRT triples the risk of blood clots forming in veins (and occasionally leading to a pulmonary embolism). However, this is very rare in healthy active women (because the risk is so low to begin with), but can be a problem in older women.

Prevention of dementia Evidence Inconclusive

Although several small studies have suggested that estrogens may improve brain function, the only randomized trial (published in February 2000) did not show any improvement in women with mild Alzheimer’s.

Prevention of colon cancer Evidence Inconclusive

Women who use HRT have a 31% lower risk of colon cancer.

Risk of uterine cancer No Effect

While estrogen alone can increase the risk of uterine (endometrial) cancer, combined HRT has no effect.

Increased risk of breast cancer Evidence Inconclusive

This risk has not been documented in randomized trials, but observational studies have shown that there is probably no effect with use of up to five years, but a 35% increase in risk after that.

Cholecystitis Evidence Strong

There is a 40% increase in the risk of cholecystitis (inflammation of the gall bladder) with HRT.

Further information can be obtained from the National Women’s Health Information Center: http://www.4women.org

Source:

SE McNagny. Prescribing hormone replacement therapy for menopausal women. Annals of Internal Medicine 1999;131: 605.