Benefits in NNT

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

Harms in NNT

  • 0.4% were harmed by having a heart attack (non-fatal)
  • 0.5% were harmed by having a stroke (non-fatal)
  • 1% were harmed by developing a blood clot in the leg or lung (non-fatal)
  • 1 in 250 were harmed (heart attack due to HRT)
  • 1 in 200 were harmed (stroke due to HRT)
  • 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: Heart attack, stroke, death, development of a blood clot

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, and included about 20000 subjects from a variety of trials. The results of these trials were very surprising for many scientists and physicians who had been recommending HRT for years, because HRT did not prevent deaths, and overall it did increase heart attacks and strokes among those who had never had a previous heart attack or stroke. It is also disturbing that blood clots in the legs and lungs were increased, although it is 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 almost entirely from a single trial. This was a very large and well done trial, but whenever one trial is the only source for results there is the possibility that those involved in the trial may be slightly different than other populations. It would be reassuring to see another trial with a different group confirm these results, although for now these data seem good enough to use for decisions about whether to use 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...