Hormone replacement therapy: to use or not to use?

To the Editor: The randomised controlled trial associated with the Women’s Health Initiative (WHI) found that long-term hormone replacement therapy (HRT) with combined oestrogen–progestin causes net harm.1 Both the article by Baber and colleagues on HRT2 and a previous editorial by Patel and colleagues3 imply that the method used to calculate the confidence intervals in the WHI report is questionable. Baber et al suggest that “a trial such as this, with multiple endpoints, should use adjusted rather than nominal confidence intervals to test individual endpoints for significance”.2 It is important that this issue is clarified.

In the WHI report in JAMA, Table 2 shows both nominal and adjusted confidence intervals for the primary and secondary outcomes.1 Nominal confidence intervals are appropriate for the preselected primary outcomes of the trial — breast cancer, coronary heart disease and the composite global-index score.4 Confidence intervals adjusted for multiple comparisons are possibly appropriate for the multiple secondary endpoints in the study, but are not advocated by all statisticians.5 In any case, the decision of Baber and colleagues to concentrate on adjusted confidence intervals for the preselected primary outcomes is not valid.4

The purpose of confidence intervals is to assess the effects of random variation or chance. It is not sensible to suggest that the extra harm that occurred in the combined HRT arm of the WHI study could be due to chance. Moreover, 42% of women in the HRT group stopped taking the drug, and 11% of women in the placebo group started taking it.1 Therefore, the reported findings of the intention-to-treat analysis underestimated the true harm to individual women taking long-term HRT. Also, if duration of treatment is important (as appears the case with breast cancer risk), and because compliance decreased over time, 5-year results underestimated longer-term treatment harm.4

The aim of the WHI trial was to assess whether long-term HRT is a useful preventive intervention for postmenopausal women. It did not assess the short-term use of HRT to relieve severe hot flushes. As Sackett points out, curative and preventive medicine are absolutely and fundamentally different in their obligations and implied promises to the individuals whose lives they hope to modify.6 As a long-term preventive intervention, HRT causes more harm than good. Although the absolute risks were small, millions of women were prescribed this treatment worldwide, causing harm to thousands. Billions of dollars were spent on an ineffective preventive intervention.6 The thousands of Australian women who stopped taking HRT on learning the results of the WHI trial made a sensible decision.