Moderate Alcohol Use and Reduced Mortality Risk: Systematic Error in Prospective Studies and New Hypotheses

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We have provided recent evidence suggesting that a systematic error may be operating in prospective epidemiological mortality studies that have reported “light” or “moderate” regular use of alcohol to be “protective” against coronary heart disease. Using meta-analysis as a research tool, a hypothesis first suggested by Shaper and colleagues was tested. Shaper et al suggested that people decrease their alcohol consumption as they age and become ill or frail or increase use of medications, some people abstaining from alcohol altogether. If these people are included in the abstainer category in prospective studies, it is reasoned that it is not the absence of alcohol elevating their risk for coronary heart disease (CHD) but, rather, their ill health. Our meta-analytic results indicate that the few studies without this error (i.e., those that did not contaminate the abstainer category with occasional or former drinkers) show abstainers and “light” or “moderate” drinkers to be at equal risk for all-cause and CHD mortality. We explore the history of this hypothesis, examine challenges to our meta-analysis, and discuss options for future research.

Introduction

The objectives of our paper consist of, first, providing a brief summary of the history of research efforts surrounding a hypothesis originally articulated by Shaper, Wannamethee, and Walker in 1988 (1), who hypothesized that a systematic misclassification error was present in most prospective studies assessing associations between alcohol use and coronary heart disease (CHD). This history laid the groundwork for testing the hypothesis using a meta-analysis of prospective studies that reported the associations between alcohol use and mortality risk from all causes and CHD (2). Second, challenges to the findings from this meta-analysis are evaluated. Third, options for future research are discussed.

Section snippets

Brief History of the Shaper, Wannamethee, and Walker Hypothesis

Shaper and colleagues suggested that the error of including persons terminating or decreasing their alcohol consumption to very occasional drinking in the abstainer category biased the findings toward making drinkers appear to be less vulnerable to CHD and abstainers more vulnerable in prospective studies. As people age and become ill or frail or increase use of medications, their alcohol consumption decreases, some abstaining altogether. If these people are included in the abstainer category,

Arguments Challenging our Meta-Analysis Findings

We turn attention to what we perceive to be arguments challenging our analyses.

Where do we go from here?

Our analyses have a number of weaknesses. However, we believe the major weakness is reflected in the nature of the studies themselves, primarily the dominance of inadequate and imprecise measurement of the major explanatory variable. Quite obviously, better study designs with well-articulated questions describing drinking patterns over long periods are in order. As well, the morbidity and case-control literatures in this domain require careful scrutiny for measurement error, and attention

Discussion

The often used term “moderate drinking” may be inappropriate for at least two reasons. First, its meaning varies across culture and time. Second, the operational definitions of “moderate” drinking vary enormously (62) Such imprecision should be unacceptable to the scientific community. It has been suggested that a more useful term may be “nonharmful”

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    Disclosure: The majority of funding for research performed by Dr. Fillmore has been derived from the National Institutes of Health (NIAAA). She has received a minor amount of seed money from NordAN, a collection of Scandinavian groups interested in the control of the accessibility of alcohol, and a minor amount of money from the International Center for Alcohol Policies to support an in-house paper on the nature of contemporary alcohol-related research and has received travel expenses from the same group at an earlier time. She has consulted for NIAAA and for the World Health Organization (WHO, Geneva and Europe). Dr. Stockwell periodically conducts consulting work for WHO and Health Canada on alcohol and other drug research issues. He is in receipt of funding from the Centre for Addictions Research of British Columbia, the British Columbia Ministry of Health, WHO, and the Canadian Institutes for Health Research. He has previously received travel expenses from the International Center for Alcohol Policies but has not received personal fees or research funds from alcohol or tobacco manufacturers or from pharmaceutical companies. Dr. Chikritzhs has received all of her research funding from the National Drug Strategy Commonwealth, Department of Health and Aging, Australia, through competitive grants with no links to the alcohol beverage industry. She has performed minor consulting to the health department in Western Australia. Dr. Bostrom has received the majority of his funding from the NIAAA and has performed statistical consulting for pharmaceutical companies and other industries, none connected with the alcohol beverage industry. The majority of work performed by Dr. Kerr has been derived from the NIAAA.

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