Letters

Impact of postmenopausal hormone therapy on cardiovascular events and cancer

BMJ 1997; 315 doi: http://dx.doi.org/10.1136/bmj.315.7109.676 (Published 13 September 1997) Cite this as: BMJ 1997;315:676

More women are excluded from treatment arm of such trials because of cardiovascular events

  1. Stephen Singleton, Director of public healtha,
  2. Kathryn Bailey, Public health scientista
  1. a Northumberland Health Authority, Morpeth, Northumberland NE61 2PD
  2. b Department of Public Health Medicine, East Surrey Health Authority, Epsom, Surrey KT19 8PH
  3. c Unit of Health-Care Epidemiology, Department of Public Health and Primary Care, University of Oxford, Institute of Health Sciences, Oxford OX3 7LF
  4. d Brent and Harrow Health Authority, Harrow, Middlesex HA1 3EX
  5. e Leicester University School of Medicine, Leicester LE2 7LX
  6. f New England Medical Center, NEMC #302, 750 Washington Street, Boston, MA 02111, USA
  7. g National Research and Development Centre for Welfare and Health, Health Services Research Unit, PO Box 220, 00531 Helsinki, Finland

    Editor—Elina Hemminki and Klim McPherson studied the impact of postmenopausal hormone therapy on cardiovascular events and cancer.1 Meta-analysis has both potential and limitations,2 and the authors comment on bias introduced when data are pooled from clinical trials designed to measure something different. Data on cardiovascular events and cancer “were given incidentally,” mostly as “reasons for dropping out.” The authors conclude that pooled data do not support the notion that hormone replacement therapy prevents cardiovascular events, but a more honest interpretation is surely that a much higher proportion of women are excluded because of cardiovascular events from the treatment arm of such trials. Given the difficulty of blinding patients and the culture connecting hormones with blood clotting, this is not surprising.

    The best information we have on the relation between hormone replacement therapy and mortality comes from the nurses' health study.3 In this study of over 120 000 women followed up since 1976, over 3600 women died, each of whom was matched with 10 controls. After adjustment for confounding variables, current hormone users had a lower risk of death; indeed, current hormone users with coronary risk factors had the largest reduction in mortality (relative risk 0.51; 95% confidence interval 0.45 to 0.57). While benefit decreased with long term use and was reversed more than five years after therapy (probably due to the increased risk of breast cancer and the “catching up” of postponed deaths), the overall impact of hormone replacement therapy on mortality was positive.

    We calculated the numbers of deaths in two cohorts of 1000 women from age 55 (the average menopausal age), one of which took hormone replacement therapy for 10 years and was followed up for 10 more years, and the other of which did not take hormone replacement therapy. We used Northumberland's age specific …

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