In Summary, for those who took the hormone replacement therapy:

Benefits in NNT

  • 100% saw no benefit
  • 0% were helped by preventing a heart problem or death
  • 0% were helped by preventing a heart attack (non-fatal)
  • 0% were helped by preventing a stroke (non-fatal)
  • None were helped (cardiovascular problem prevented)

Harms in NNT

  • 1% were harmed by developing a blood clot in the leg or lung (non-fatal)
  • 1 in 100 were harmed (blood clot in the leg/lung)

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Source: Gabriel Sanchez R, Sanchez Gomez LM, Carmona L, Roqué i Figuls M, Bonfill Cosp X. Hormone replacement therapy for preventing cardiovascular disease in post-menopausal women. Cochrane Database of Systematic Reviews 2005, Issue 2. Art. No.: CD002229

Efficacy Endpoints: Heart attack, stroke, death

Harm Endpoints: Development of a blood clot, death

Narrative: Hormone replacement therapy ('HRT') was believed for many years to potentially restore cardiovascular hormonal balance for women after menopause, thus reducing heart attacks, strokes and death. While this therapy has been shown to reduce hot flashes,1 before the past ten years there were no major trial results to answer the question of whether or not HRT works to prevent heart problems and strokes.

This review examined the highest quality randomized trials that tested HRT for preventing heart attacks, strokes, and death among women who have already had a heart attack or stroke, and included over 5000 subjects from trials. The results were very surprising for many scientists and physicians who had been recommending HRT for years, because HRT did not prevent any important cardiovascular problems or deaths, and overall it did increase blood clots in the legs and lungs. The numbers of stroke and heart attacks were just slightly higher in the group on HRT, but this wasn't a large enough difference to be considered 'statistically significant'. It is also important to note that despite the increases in heart attacks, strokes, and blood clots there was no increase in deaths due to HRT.

Caveats: The results in this review come from trials that are of a decent, but not very large, size. It is likely that larger trials asking the same question would show a 'significant' increase in heart attacks and strokes due to HRT. It is also important to note however, that there are benefits of HRT as well, including reduced hot flashes and small reductions in colon cancer and fractures, and it may be worth integrating all of these in making a decision about whether or not HRT is right for a given patient.

Author: David Newman, MD

Published/Updated: July 8, 2011

  1. The Title Bar

    The title bar is color-coded with our overall recommendation.

    • Green: Benefits outweigh risks.
    • Yellow: Unclear risk/benefit profile.
    • Red: Benefits do not outweigh risks.
    • Black: Obvious harms, no clear benefits.
  2. Tip content...