Effects of Hormone Replacement Therapy on Cholesterol Levels in Elderly Women

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The summary below is from the full report titled "Effects of Hormone Replacement Therapy on Serum Lipids in Elderly Women. A Randomized, Placebo-Controlled Trial." It is in the 1 May 2001 issue of Annals of Internal Medicine (volume 134, pages 754-760). The authors are EF Binder, DB Williams, KB Schechtman, DB Jeffe, and WM Kohrt.

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

Coronary heart disease (CHD) is caused by blockage of blood vessels in the heart and is the most common cause of death among older women. Anything that reduces the risk of blood vessel blockage may decrease death from CHD in this group. Higher levels of "good cholesterol," known as HDL (high-density lipoprotein), protect blood vessels against blockage by fatty deposits, while "bad cholesterol," known as LDL (low-density lipoprotein), worsens fatty deposits. Previous studies indicate that in postmenopausal women younger than 75 years of age, hormone replacement therapy (HRT) is associated with a lower rate of death from CHD.

Why did the researchers do this particular study?

The researchers wanted to know whether HRT use increases HDL levels and decreases LDL levels in women older than 75 years of age.

Who was studied?

Fifty-nine women 75 years of age or older with mild to moderate physical frailty were included in the study.

How was the study done?

At the beginning of the study, all participants had tests of fat levels in the blood (HDL, LDL, total cholesterol, and triglycerides) and completed a survey about diet habits. They were randomly assigned to take either HRT pills (consisting of the hormone estrogen) or placebo pills for the next 9 months. Women with a uterus who were assigned to the HRT group were also given progesterone (another hormone) to avoid overgrowth of uterine tissue that could become cancerous, while those in the placebo group received placebo pills. Thirty-nine women received active HRT, and 20 women received placebo. Nine months after the study began, fat levels in the blood were tested again.

What did the researchers find?

Two women receiving placebo and 9 receiving HRT dropped out of the study because of side effects, including breast discomfort, bloating, or vaginal bleeding; personal inconvenience; or chronic medical conditions not related to the medication. Three others in each group did not provide blood samples at the 9-month follow-up. Fifteen women in the placebo group and 27 women in the HRT group were evaluated. Significant increases in HDL cholesterol levels and decreases in LDL cholesterol levels were found in the HRT-treated women compared with women who received placebo. Serum triglyceride levels were unchanged.

What were the limitations of the study?

Because the study group was small and the participants had to meet many criteria to be in the study, the results may not apply to all women older than 75 years of age. For example, since all the women in the study were mildly to moderately frail, the results may not apply to physically fit or severely frail women. The side effects that contributed to a 19% drop-out rate may limit usefulness of this therapy for many women. Finally, the study did not follow women to see whether HRT actually prevented CHD.

What are the implications of the study?

HRT can favorably affect cholesterol levels (increasing HDL and decreasing LDL) in elderly women.