Risks associated with alcohol consumption may be exaggerated

A research letter from Mary C. Vance; Tanner J. Caverly and Rodney A. Hayward published online in JAMA Internal Medicine raises the issue of how systematic measurement error can bias estimates of the population mean (eg, biased estimates of average alcohol use). They highlight that the consequences of systematic measurement error on the associations between risk factors and outcomes are often overlooked.
A recent example is a 2016 study, published in the Lancet, which found that any level of alcohol consumption was associated with increased risks for adverse health conditions. This led to widely publicised reports of no safe level of alcohol consumption. The study did not account for potential misclassification owing to underreporting of alcohol use. Systematic underreporting of alcohol use could result in overestimating the association between a low amount of alcohol consumption and the risk of adverse health outcomes, especially given evidence that heavy drinkers underreport their true levels of alcohol consumption by up to 40% to 65%.
Vance and colleagues conducted a quality improvement study to assess the potential implications of systematic underreporting of alcohol use on the observed results in that recent, well-publicized study. The research focused on two types of drinking: at-risk drinking, which was defined as having three to five drinks per day, and heavy drinking, defined as having six or more drinks each day. The researchers assumed two types of underreporting occurred in the previous studies — one in which at-risk drinkers underreported by one to two drinks per day, and another in which heavy drinkers underreported their actual consumption dramatically to hide their drinking problems.
Vance and colleagues found that, if 30% of those who consumed at least three drinks each day had downplayed their alcohol consumption, then the observed RRs of those who reported one to two drinks per day were about the same as the risks observed in the Lancet study. If 40% of at-risk and heavy drinkers underreported their alcohol consumption, the observed RRs began to exceed those observed in the study.
Vance and colleagues added that “the present analysis demonstrates the importance of considering how systematic underestimation of a risk factor can overestimate the consequences of low exposure to the risk factor.”
Source: Underappreciated Bias Created by Measurement Error in Risk Factor Assessment—A Case Study of No Safe Level of Alcohol Consumption. Vance MC, Caverly TJ, Hayward RA. J MA Intern Med. Published online December 09, 2019.