In Some Women, Postmenopausal Hormone Use Increases Short-Term Risk for Heart Disease, but Decreases Risk in the Long Term

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The summary below is from the full report titled "Postmenopausal Hormone Use and Secondary Prevention of Coronary Events in the Nurses' Health Study. A Prospective, Observational Study." It is in the 3 July 2001 issue of Annals of Internal Medicine (volume 135, pages 1-8). The authors are F Grodstein, JE Manson, and MJ Stampfer.

What is the problem and what is known about it so far?

Sorting through the potential benefits and harms of postmenopausal hormone use can be confusing. For example, established benefits include less osteoporosis (thinning of the bones) and fewer menopausal symptoms. Harms include small increases in the risk for breast and ovarian cancer. For many years, the use of postmenopausal hormones has been believed to decrease heart disease. However, a recent careful study showed that among women with known heart disease, hormone use for 1 to 3 years did not decrease repeated episodes of heart disease and did increase chances of having blood clots in the legs and lungs. However, more information is needed about the harms of taking hormones over an increasing number of years.

Why did the researchers do this particular study?

To describe how often heart disease recurs in postmenopausal women who take hormones for different lengths of time.

Who was studied?

The study included 2489 postmenopausal nurses with known coronary artery disease (narrowing of the arteries that supply blood to the heart), who were observed from 1976 to 1996. No women with stroke or cancer were studied.

How was the study done?

Every 2 years, the women answered questions about hormone use and major health problems. The researchers also reviewed the women's medical records and a national registry to identify deaths among these women and the causes of death.

What did the researchers find?

Compared with women who never took hormones, women who took hormones for less than 1 year had a 25% increase in risk for recurrent coronary heart disease. However, women who took hormones for 2 years or longer had decreased risk for recurrent heart disease. Longer duration of use was associated with lower risk. These effects of hormone use were seen after other risk factors, such as age, smoking, blood pressure, and body weight, were accounted for and regardless of whether the hormones used consisted of estrogen alone or estrogen combined with progestin.

What were the limitations of the study?

Self-reports of hormone use, as were used in this study, may not be totally accurate. More important, women who take hormones for a long time may differ in many ways from those who do not; for example, they might be more physically active or have healthier diets. It can be difficult to sort out whether the differences in heart disease that accompany postmenopausal hormone use are due to the hormones or something else.

What are the implications of the study?

Risk for recurrent coronary heart disease in postmenopausal women with known heart disease is increased with short-term (up to 1 year) use of hormones. Risk for recurrent coronary disease decreases with longer hormone use.