How to Make Sense of Medical Headlines and Studies
How should you respond when you hear or read medical headlines that are either sensational or confusing?
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This kind of thing happens often in medical science. Did you know that heavy coffee drinkers have higher rates of lung cancer than those who don’t drink any coffee? But before you sell all your stock in Starbucks, let me tell you one more fact: heavy coffee drinkers are much more likely to be smokers than those who don’t drink coffee.
Experiments Must Confirm Hypotheses
To prove that one thing causes another takes a lot more work than just noting that they happen together. Experiments need to be performed to test the hypothesis. Tape the mouth of the rooster shut and see if the sun still rises. Go to a place without roosters and see if the sun rises. Compare smokers who drink lots of coffee with those who do not. Have heavy coffee drinkers switch to decaf and see if the cancer rate goes down. All hypotheses must be thoroughly tested before they can be relied on.
Error 2. Science Does Not Equal Fact
The second error people make is to equate science with fact. A scientist makes a finite number of observations and draws conclusions from them. But often the best sounding theories--the ones that seem obvious--are knocked flat when put to the test.
Often the best sounding theories--the ones that seem obvious--are knocked flat when put to the test.
A good example of this is the theory that post-menopausal women should have hormone replacement therapy. When I first started in practice, it was believed that women should get estrogens after menopause. That belief came from the observation that prior to menopause, women have a low rate of heart attacks and a low rate of bone loss that could lead to osteoporosis, but after menopause heart attacks and osteoporosis rates went way up. The belief that post-menopausal women should take hormones was bolstered by a study that looked at a huge number of women retrospectively and found that those who had taken hormones had lower rates of heart disease.
But retrospective studies (ones that look back at populations looking for trends) are unreliable, and so scientists did a prospective study to prove the benefits of hormones. They took a large number of women and put half of them on hormones and gave the other half a sugar pill, or placebo, and watched to see what happened. To the dismay of the hormone manufacturers, the women who got hormones had an increase in heart attacks, not a decrease. That made us all do a 180 and take all the women to whom we have been pushing hormones off of them.
Were we wrong to push hormones? No, the best information we had at the time said that it helped; but when the better information came along we had to change what we were saying. This is the nature of science: it changes. Scientific theories should always be questioned; the more questions they stand up to, the more solid the theory.
Error 3: Groups Don’t Equal Individuals
The third big mistake people make is to assume that science on a group must apply to them individually. There are several ways this can go wrong.