WHI Study: No increased all-cause mortality with menopausal hormone therapy

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Menopausal hormone therapy with conjugated equine estrogens (CEE) plus medroxyprogesterone acetate (MPA) did not increase all-cause mortality and disease specific mortality in participants of Women’s Health Study(WHI) after nearly 2 decades of follow-up says the results of new data analysis published online in JAMA.

This study is specifically important because earlier studies have never looked into disease specific and all-cause mortality of women receiving hormone therapy. Menopausal hormone therapy is debated since decades, and the interest in prescribing HT waxes and wanes as new data is published.

The researchers analyzed data from two studies:  the first study was estrogen with progestin trial and the second was estrogen only trial published in JAMA in 2002 and 2004 respectively.

The researchers conducted an extended follow-up of women included in this trial for 18 years. The combined trial included 16,608 women with a uterus while the estrogen only trial included 10,739 women with a history of hysterectomy.

In the estrogen+ progesterone group, 8506 women were randomized to receive HT and 8102 were given placebo for a median of 5.6 years. In estrogen only group, 5310 women took estrogen and 5429 were placed on placebo for a median 7.2 years.

For the current analysis, the researchers pooled the data from these 2 studies, amounting to a total of 27,347 women, with ages between 50 to 79 years and 80.6% being white. These women were followed up for 18 years. There were 7489 deaths through December 31, 2014, including 1088 during the trial and 6401 since the trials ended.

All-cause mortality did not defer between the two study arms, it was 27.1% in the hormone therapy group vs 27.6% in the placebo group (hazard ratio [HR], 0.99 [95% CI, 0.94-1.03]) in the overall pooled cohort. The figures were similar for cardiovascular and cancer mortality.

The only difference in mortality was observed for breast cancer, with estrogen+ progesterone group facing a 44% increased risk relative to placebo while estrogen was protective against breast cancer and reduced the risk by 45%. 

Both the earlier trials were stopped early when it became clear that HT did not improve the CVD outcomes as for both trials the primary outcome was prevention of chronic diseases and not to gauge the effectiveness of HT in managing menopausal symptoms.

Hence, the results of the study are especially important as they reassure the physician and patient that HT can be safely used for management of menopausal symptoms with a positive risk/benefit profile.

At the same time, it should also be noted that HT increases risk of stroke and breast cancer and decreases risk of endometrial and uterine cancer and hip fractures.

Still, the results of the study cannot be applied in every situation and for all women. Women who are at high risk for blood clots and breast cancer, the added increased risk may outweigh the benefit of alleviating menopausal symptoms individually.

The article is accompanied by an editorial by Melissa McNeil, MD, MPH, from the University of Pittsburgh in Pennsylvania which highlights the complexity of the issue. She writes, "Although the long-term data on total and cause-specific cumulative mortality of pooled data for hormone users vs nonusers is both compelling and reassuring, several questions remain. Perhaps the most challenging question involves the issue of whether there is a difference in overall mortality by age and menopausal status at the time of initiation of hormone therapy."

"This reduction in mortality...thus remains suggestive but not definitive," Dr McNeil further added. 

"Other questions that remain include the optimal duration of hormone therapy and if an even earlier initiation of hormone therapy, such as within 2 years of the menopausal transition, would provide additional benefits."

So, the takeaway from the study results is: HRT can be prescribed to treat menopausal symptoms with a positive risk-benefit profile without increasing all cause, cardiovascular and cancer mortality. It however should not be prescribed for prevention of  CVD and other chronic conditions.

The authors have disclosed no relevant financial relationship.