Posted on: Saturday, February 26, 2005

PRESCRIPTIONS
Reconsider toasting moderate-drinking study

Bu Dr. Landis Lum

Q. I'm a man, but read that women who were moderate drinkers (up to one drink a day) had better cognitive performance than nondrinkers. Shall I start drinking wine — and help my heart, too?

A. This came from the Nurses Health Study in the Jan. 20 New England Journal of Medicine. But remember how we all thought that estrogens reduced heart disease? Estrogens improve good (HDL) cholesterol, and when hormone levels drop at menopause, heart attacks rise.

In 1985, the journal published another article from this same Nurses Health Study: "A prospective study of postmenopausal estrogen therapy and coronary heart disease." It studied 32,000 women and found those on hormones had 50 percent less heart disease than those who were not, even accounting for obesity, smoking, hypertension, cholesterol and diabetes.

But now we know estrogens increase heart disease. Why should we believe these latest studies?

It's because these are much more accurate studies known as randomized controlled trials, while the Nurses Health Study is a weaker "observational" study that followed two groups of women — those who decided to take estrogen, and those who didn't.

The women who took estrogen were different from those who chose not to: They exercised more, ate better 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 or neutralized the power of suggestion by doctor or patient.

In randomized controlled trials, patients randomly are assigned to two groups: one takes the drug and the other takes a fake drug (placebo). Ideally, neither the doctors nor the patients know which group they're in — so-called "double-blinding."

You follow both groups to uncover any differences in health. Only RCT's can eliminate confounders and bias, and show the true effects of our potions.

There are no RCT's of the effect of alcohol on either cognition or heart disease. Too bad. Like the women who didn't take estrogen, nondrinkers may be sicker than you think.

Dr. George Vaillant of Harvard studied males from their teens into adulthood, and found that 33 percent of lifelong abstainers had poor physical health in childhood versus 14 percent of moderate drinkers.

And while 35 percent of moderate drinkers came from warm childhood homes, only 16 percent of nondrinkers did. And ill people may stop drinking. So if nondrinkers have a disproportionate share of sickies with poor memory or weak hearts, then observational studies like the Nurses Health Study would erroneously find moderate drinking improves memory or reduces heart disease when in fact the opposite may be true.

I wouldn't pop the champagne quite yet.

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.