On February 15, 2010 the NIH issued a news release about a new analysis reported in the Annals of Internal Medicine on data from the Women's Health Initiative (WHI). The study reevaluated whether or not combination hormone therapy (estrogen+progestin) increases the risk of heart disease in healthy postmenopausal women. Researchers from the National Heart, Lung, and Blood Institute (NHLBI) and the Harvard School of Public Health reanalyzed data from the WHI, comparing the effects of hormone therapy (HT) on heart disease risk among women who began hormone therapy within 10 years of menopause to women who began therapy more that 10 years after menopause. Recently, there has been a lot of debate among clinicians and researchers whether or not the time between the start of menopause and the initiation of hormone treatment affects the cardiovascular risk. Some believed that the risk may not be present in women who start HT shortly after they go into menopause. In this new study, the researchers compared women who started combination hormone (estrogen+progestin) treatment within 10 years of menopause to women who began therapy more than 10 years after menopause and examined the impact on heart disease over time (up to eight years). The new study did not include women who took estrogen only.
The researchers reported a trend toward a possible increased risk of heart disease in the first two years among the women who started hormone therapy within 10 years after menopause and the increased risk persisted in this group an average of 6 years, after which those in the treatment group appeared to have a lower risk of heart disease compared to similar women who were not on combination hormone therapy. In contrast, women who started hormone therapy 10 years or more after menopause were nearly 3 times more likely to develop heart disease within the first two years of treatment compared to women on placebo. These women continued to be at increase risk of health disease throughout the 8 years of follow-up.
Jacques E. Rossouw, MD, chief of the NHLBI Women's Health Initiative Branch and a coauthor of the paper, added, "Although the number of recently menopausal women who would be expected to suffer a heart attack during the first years of combination HT is small, the risk is likely to be real." In the NHLBI press release, acting director, Susan B. Shurin, MD, said, "Today, most women who take hormone therapy for menopausal symptoms begin therapy shortly after menopause. Based on today's study, even these women appear to be at increased risk of heart disease for several years after starting combination hormone therapy." This new data reinforces the need for women to discuss their potential risk for cardiovascular disease and for other conditions like stroke and breast cancer with their doctors when considering combination HT.
So what have we learned from this study? Women who start combination HT to treat the symptoms of menopause within 10 years of menopause, should not expect the treatment to protect them from heart attacks, and may even have a possible slight increase in risk. As with many studies, the statistical significance of the women in the study may not be sufficient to make this the final word on the topic but it is unlikely that additional information on the scale of this study will be available in the near future.