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UCSF points out flaw in studies tying alcohol to heart health
- Sabin Russell, Chronicle Medical Writer
Thursday, March 30, 2006
With all the contradictory claims made these days about the health
benefits of low-fat diets, the harm of hormone replacements and the
dangers of pain relievers, at least we still know that a drink or two
a day is good for the heart.
Well, maybe not.
Researchers at UCSF pored through more than 30 years of studies that
seem to show health benefits from moderate alcohol consumption, and
concluded in a report released today that nearly all contained a
fundamental error that skewed the results.
That error may have led to an erroneous conclusion that moderate
drinkers were healthier than lifelong abstainers. Typically, studies
suggest that abstainers run a 25 percent higher risk of coronary heart
disease.
Without the error, the analyses shows, the health outcomes for
moderate drinkers and non-drinkers were about the same.
"This reopens the debate about the validity of the findings of a
protective effect for moderate drinkers, and it suggests that studies
in the future be better designed to take this potential error into
account,'' said Kaye Fillmore, a sociologist at the UCSF School of
Nursing and lead author of the study.
The common error was to lump into the group of "abstainers" people who
were once drinkers but had quit.
Many former drinkers are people who stopped consuming alcohol because
of advancing age or poor health. Including them in the "abstainer"
group made the entire category of non-drinkers seem less healthy in
comparison.
This type of error in alcohol studies was first spotted by British
researcher Dr. Gerry Shaper in 1988, but the new analysis appears to
show that the problem has persisted.
Fillmore and colleagues from the University of Victoria, British
Columbia; and Curtin University, in Perth, Australia, analyzed 54
different studies examining the relationship between light to moderate
drinking and health. Of these, only seven did not inappropriately
mingle former drinkers and abstainers.
All seven of those studies found no significant differences in the
health of those who drank -- or previously drank -- and those who
never touched the stuff. The remaining 47 studies represent the body
of research that has led to a general scientific consensus that
moderate drinking has a health benefit.
Fillmore's team of researchers took their initial finding one step
further, and introduced the error into the data compiled in the seven
studies and, voila, the results changed to show drinkers had better
health than abstainers.
"We are not proving anything,'' Fillmore insisted. "But the results
are certainly suggestive.''
The UCSF study appears today in an online edition of the journal
Addiction Research and Theory.
Kaiser Permanente cardiologist Dr. Arthur Klatsky, who led some of the
largest studies showing a protective effect for moderate alcohol
consumption, said his first study in 1981 contained the flaw, but
subsequent studies took it into consideration.
"Without question, it is a serious flaw, which we have readily
admitted,'' he said. He contends, however, that Fillmore's analysis
mistakenly attributes the same mistake to later research.
"The evidence is still pretty compelling that there are likely to be
benefits'' from moderate drinking, he said. In addition, he said,
studies show that alcohol raises the level of HDL -- the so-called
good cholesterol -- and also has anti-clotting effects, which can
reduce the risk of heart attack.
Klatsky said that there are inherent weaknesses in all the
epidemiological studies of alcohol and heart health. What is needed,
he said, is a randomized trial in which a group is assigned to consume
one or two drinks a day and another abstains, and their comparative
health is assessed over a period of years.
Dr. Tim Naimi, a physician who works for the National Center for
Chronic Disease at the Centers for Disease Control and Prevention in
Atlanta, said "the whole field of 'moderate drinking' studies is
deeply flawed,'' because of the lack of randomized trials.
In a study published in May 2005 in the American Journal of Preventive
Medicine, Naimi and other CDC colleagues found that the comparatively
higher risk of heart disease in abstainers could be explained by
socioeconomic factors rather than lack of protection from alcohol
consumption.
Non-drinkers, for example, tended to be poorer than drinkers, had less
access to health care, and had less healthy diets.
"Anyone who suggests that people should begin drinking, or drink more
frequently, to reduce the risk of heart disease is misguided,'' he
said.
E-mail Sabin Russell at srussell@sfchronicle.com.
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