The Pharmaceutical Journal
Vol 272 No 7296 p500
24 April 2004

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Oestrogen hormone therapy increases stroke and DVT risk

Unopposed oestrogen therapy increases the risk of stroke and deep vein thrombosis in post menopausal women with prior hysterectomy, a large, multi-centre trial has shown. The data provide further evidence of the risks associated with long-term hormone replacement therapy (PJ, June 7, 2003, p783).

The study, part of the US Women’s Health Initiative trial, also found that the hormone did not reduce the risk of coronary heart disease. In addition, it did not significantly affect the risk of breast or colorectal cancer but did reduce the risk of hip and other fractures.

Conjugated equine oestrogen should not be recommended for chronic disease prevention in postmenopausal women, the authors conclude. (The conjugated equine oestrogen Premarin was the agent used in the trial.)

The study was stopped early because of the findings regarding stroke and CHD. However, there was no increased risk for total mortality with the hormone.

“We believe the findings support current Food and Drug Administration recommendations that hormone therapy only be used to treat menopausal symptoms and that it be used at the smallest effective dose for the shortest possible time,” said Barbara Alving, acting director of the US National Heart Lung and Blood Institute, which sponsored the study.

WHI project officer Jacques Rossouw added: “The results make clear that hormone therapy does not protect women against coronary heart disease and increases their risk for stroke. This may be especially true for older women, such as those aged 60 and older in this study.”

The trial involved 40 clinical centres in the US and over 10,000 generally healthy postmenopausal women aged 50–79 years. They took either Premarin 0.625mg daily or placebo and were followed for an average of 6.8 years.

On average, for every 10,000 women each year, oestrogen use resulted in 12 extra cases of stroke (fatal and non-fatal) and six extra cases of venous thrombosis (JAMA 2004;291:1701).

The NHLBI adds that a separate report on the effect of oestrogen on dementia and cognitive function will be published soon.

In a statement, Premarin manufacturer Wyeth pointed out: “The risk of stroke seen with oestrogen in the WHI is consistent with information in the existing product label.”

It added that the report addresses the use of oestrogen as a long-term preventive agent and does not take into account the benefits of oestrogen therapy for the relief of moderate to severe menopausal symptoms.