HRT - "the old days"

The Nurses' Health Study was one of the largest studies ever done by the medical community. It was initiated in 1976, and initially included married nurses aged 30-55 (in that year). Its initial objective was to investigate the long term consequences of the use of oral contraceptives, and subsequently broadened its objectives. For a detailed history, Click Here. In 1996, the New England Journal of Medicine (vol 335, p453), published results derived from this study concerning the protective effect of HRT among women taking estrogen and progestin (a synthetic form of progesterone). They concluded that the relative risk of major coronary disease (compared to nurses not taking hormones) was 0.39, a dramatic reduction in risk! The Margin of Error, is large - it spans the range between 0.19 and 0.78! So the reduction in risk could be anywhere between 22% (0.78) and more than a factor of 5 (0.19). For use of estrogen alone, the reduction in risk is not quite so large - 0.60, still very significant, although the error interval is between 0.43 and 0.83. Three years after stopping the medication, the risk reduction is decreased significantly.

The authors of the study state clearly that "Women who take hormones are a self-selected group and usually have healthier lifestyles with fewer risk factors than women who do not take hormones. In general-population samples, hormone users, as compared with nonusers, have more years of education, are leaner, drink more alcohol, and participate in sports more often, even before starting to use hormones." Because of this, the analysis included an adjustment for the many known risk factors.

The obvious conclusion from this study was that HRT offers significant protection against coronary disease. Consequently, women were encouraged to utilize post-menopausal HRT even if their symptoms did not require it. Subsequent studies did not show similarly beneficial results, and currently, HRT is not recommended for protection.