Division of Biostatistics, Washington University Medical School, St. Louis, MO 63110
On the basis of health examinations in a large cohort, Klatsky et al. (1) reported that the frequency of wine drinking was independently related to lower mortality risk, especially for coronary disease and respiratory deaths. The findings of this study are important, yet several unaddressed problems remain.
First, this study did not clearly relate the age of the subjects to the beneficial effect of alcohol. A study in England and Wales reported that net alcohol-attributable deaths were significantly different for different age groups (2). These authors concluded that the net beneficial effect of alcohol intake was negative for those aged less than 55 years but was positive for those aged greater than 55 years. Since the average age of subjects (40.6 years) and the average age of subjects who later died (60.8 years) in the study by Klatsky et al. (1) were below and above 55 years of age, respectively, Klatskys results would be more solid if the beneficial effect of wine in the different age groups could be analyzed.
In addition, although the drinking habits of all subjects were derived from 19781985 health examinations of 128,934 adults in San Francisco and Oakland, California, the analysis of relative mortality occurred in December 1998, about 20 years later. Subjects drinking habits might have changed in the long interval of this study. For example, it has been reported that former drinkers might relapse into drinking again under severe psychosocial stressors (3). It is also possible that some drinkers could have stopped drinking and become former drinkers. Did any subjects change their drinking habits during those 20 years? If the ratio of subjects who have changed their drinking habits is significant, the results of Klatsky et al. will be questionable.
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