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Critique 220: An unusual analysis relating alcohol intake to mortality – October 16, 2018

The authors of this treatise on alcohol consumption and mortality combined, for an unclear reason, results from two, very different studies: one from the Veterans’ Health Administration, based on outpatient clinical medical records, and the other from a national survey in the USA [The National Health Interview Survey (NHIS)]. Unfortunately, the VA data did not adjust for tobacco use or other important lifestyle habits, and are not useful in judging the effects of alcohol consumption on mortality.

While the NHIS survey included data on potential confounding, both it and the VA study based their analyses on a single estimate of alcohol consumption. The authors then created a variable that they stated was associated with the lowest risk of mortality and compared results from such alcohol intake with data from subjects reporting less or more alcohol. They combined data on all subjects reporting 1 to 2 drinks/week, so did not have the ability to provide a precise estimate of the association between low levels of intake and mortality risk. They did not comment on the effects that under-reporting of alcohol would have on their studies (and most investigators agree that the self-reported level of alcohol consumption is usually an under-estimate of actual consumption). Further, they did not point out the very much higher risk of mortality of non-drinkers, compared with moderate drinkers, demonstrated in their data.

To the extent that people accurately reported their past drinking status (never vs former), this study should put to rest concerns that protective associations of drinking versus non-drinking arise from inclusion of former drinkers into non-drinking groups. Never drinkers had higher risk of mortality than former drinkers in this study.

There are considerable data from many well-done cohort studies that have repeated assessments of alcohol intake over many decades and the subsequent risk of mortality. Such studies provide very clear and consistent results indicating a J-shaped curve: lower risk of mortality for light and moderate drinkers than for non-drinkers (even lifetime abstainers) and some increase in risk for heavy drinkers. These are the studies that can provide reliable information upon which drinking guidelines for different individuals and populations can be based. Reference: Hartz SM, Oehlert M, Horton AC, Grucza RA, Fisher SL, et al. Daily Drinking Is Associated with Increased Mortality. Alcoholism: Clin & Experimental Research 2018; pre-publication.

DOI: 10.1111/acer.13886

For the full critique of this paper by members of the International Scientific Forum on Alcohol Research, please click here.

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