PRESCRIPTIONS
Some medical studies better than others
By Landis Lum
I was at Turtle Bay last month, where Kaiser was hosting a conference on "evidence-based medicine." What is it, and why should you care? It's medicine that's based on well-conducted studies, not on anecdotal information.
Frustrating, isn't it, when you're told one thing, then new research appears and you're told the opposite?
For example, we all used to think that estrogens protected women against heart disease. After all, when estrogen levels drop at menopause, the risk of heart attacks rise. Estrogens improve good (HDL) cholesterol.
In 1985 the New England Journal of Medicine published "a prospective study of postmenopausal estrogen therapy and coronary heart disease" which studied 32,000 women and found that those on hormones had 50 percent less heart disease than those who were not, even accounting for obesity, smoking, hypertension, cholesterol and diabetes.
So by replenishing one's estrogen to the same levels as in our youth, we'd keep our hearts, brains, and bones young forever. (Doesn't this sound suspiciously like the present pushers of DHEA and growth hormone?) But now we have studies that show that estrogens actually increase heart disease (as well as breast cancers and dementia). Why should we believe them?
It's because these are much more accurate studies known as randomized controlled trials, while the 1985 one was a weaker "observational" study that followed two groups of women forward through time — those who had decided to take estrogen, and those who had not.
It turns out that the women who took the estrogen in these studies were different than those who chose not to do so: They exercised more, ate more healthful diets and got better medical care. These are called confounding factors, and were the real reasons these women had fewer heart attacks.
With observational studies, you can never be sure you've discovered all the confounders, nor that you have eliminated the power of suggestion by doctor or patient.
In randomized controlled trials, patients are randomly assigned to two groups in which one takes the drug and the other takes a fake drug (placebo). Neither the doctors nor the patients know which group they're in — this is the "double-blinding" method. You again follow both groups forward in time to track any differences in disease or cure rate between those taking the drug or having the procedure and those who do not. Only randomized controlled can eliminate confounders and bias, and show the true effects of our potions.
I was actually one of the tutors at Turtle Bay, where doctors learned how to judge the quality of research studies. Nearly all the quick cures for obesity, energy, arthritis, etc. in stores and on the Internet are based on bad or even nonexistent research. Go to sources such as medlineplus.gov to get the real scoop!
Dr. Landis Lum is a family-practice physician for Kaiser Permanente and an associate clinical professor at the University of Hawai'i's John A. Burns School of Medicine.
Send your questions to Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Honolulu, HI 96802; fax 535-8170; or write islandlife@honoluluadvertiser.com. This column is not intended to provide medical advice.
