Chance News 15
More on medical studies that conflict with previous studies
Humans, being what they are, it is only natural that when a study's consequences seem plausible there is no need to look too closely. On the other hand, when the outcomes go against what was expected, a great deal of inspection is called for. See this previous discussion.
The Wall Street Journal of February 28, 2006 details possible reasons for why the Women's Health Initiative might have had design flaws leading to "murky results." In summary, the WSJ reported:
Calcium/Vitamin D study
Message: Supplements don't protect bones or cut risk of colorectal cancer.
Problem: Those in placebo group also took supplements in many cases.
Low-fat diet study:
Message: Doesn't cut risk of breast cancer.
Problem: Few met the fat goal.
A 22% drop in risk for women who cut fat the most got little emphasis.
Message: No benefit, possible increased cancer and heart risk.
Problem: Most in study were too old for this to apply to menopausal women.
More generally, according to the WSJ, "Design problems in all of the trials mean the results don't really answer the questions they were supposed to address. And a flawed communications effort led to widespread misinterpretation of results by the news media and public."
In particular, in order to reduce the number of participants for the studies, "more than half [of the women] took part in at least two of them, and more that 5,000 were in all three trials." As might be imagined, "Among problems this posed was simple burnout" which "contributed to compliance problems that plagued all three and hurt the reliability of their results."
Another problem was the difficulty of double blinding for the hormone study since any hot flashes would indicate to the patient (and to her physician) that she was in the placebo arm; to get around this impediment, the vast majority of the women recruited were well past menopause, thus biasing the results against the benefits of hormone replacement.
So where are we after 68,132 female participants, "fifteen years and $725 million later"? More than likely, the Women's Health Initiative study will be in and out of the news for some time to come because of its ambiguity.
Submitted by Paul Alper