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Hormone Hell
By Melissa Hendricks
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Some consumer health advocates go a step further. They blast drug companies, which they say plied doctors with misleading information about hormone therapy, inflating its virtues. "They preyed on women's fears of aging and age-related diseases," says Amy Allina, program director for the National Women's Health Network. "Health care decision making needs to be based on science and not on marketing and hope."
But by law, drug companies are not allowed to make claims other than those approved by the FDA. Even if the companies' marketing was aggressive, defenders say, it was in keeping with then-current medical opinion.
What has changed is medical opinion. And the WHI study is only the most dramatic example of this change. Researchers now realize, for example, that while estrogen does indeed shift cholesterol toward healthier levels, the hormone also raises triglycerides—which increases the risk of heart disease. Further, researchers now recognize several shortcomings in earlier studies. That research involved observational studies, a type of experiment in which researchers watch people who are already taking a drug or practicing a particular behavior. Observational studies are commonly used in medical research, and are an invaluable tool for developing hypotheses. But they cannot prove cause and effect.
For example, scientists originally observed that women who used HRT had lower rates of heart attack, broken bones, Alzheimer's disease, depression, and incontinence. But in more recent studies, researchers have discovered striking differences between women who decide to use HRT and those who decide to forgo it. "Out in the real world, women who take estrogen tend to be healthier than women who don't," explains Susan Johnson, an obstetrician-gynecologist who directs the Menopause Clinic at the University of Iowa Hospital. They also tend to be thinner, have better access to medical care, know more about health, and more faithfully follow doctors' orders. All this makes interpreting observations tricky. Which deserved credit for the good health of women taking HRT: hormones or health-conscious behavior?
The latest research on hormone therapy has used a more rigorous, more costly approach called evidence-based medicine. Its gold standard is the placebo-controlled, randomized clinical trial in which researchers divide a comparable set of volunteers into two groups, give a drug to one group and a placebo to the other, and look for any differences in outcome.
As we now know, the results of clinical trials of HRT have contradicted several of the conclusions drawn from observational studies. The first large, randomized clinical trial of HRT for heart disease was the Heart and Estrogen/Progestin Replacement Study (HERS). The 20-center trial involved 2,763 postmenopausal women with heart disease who were followed for an average of four years.
In 1998, HERS scientists reported that the women taking HRT had a 50 percent higher risk of heart attack and related events during their first year on the therapy than the women taking the placebo. The researchers were so surprised by the finding that they had the pills tested to make sure they had not accidentally switched the hormones and the placebo. But they had not reversed the pills.
Along with HERS, other clinical studies indicated that long-term use of HRT carried risks, ranging from blood clots to gallbladder surgery. But nothing has drawn the attention of women, doctors, and the media as much as the results of the WHI study of combination therapy.
The largest clinical trial of HRT, the WHI study involved 16,608 healthy postmenopausal women ages 50 to 79, half of whom were given estrogen and progestin therapy. Scientists say the research finally offers definitive evidence that the risks of long-term combination therapy outweigh its benefits. And there were benefits: Women on HRT had fewer hip fractures and a lower rate of colorectal cancer. But the risks—of breast cancer, heart attack, blood clots, and stroke—tipped the balance. The scientists found a 29 percent increase in heart attacks, 41 percent increase in strokes, 26 percent increase in breast cancer, and doubling in the rate of blood clots.
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