The majority of epidemiologic studies have shown that both the positive and negative health effects of alcohol consumption are modified by the socio-economic status (SES) of individuals, with truly moderate drinkers who are from higher SES strata having better health outcomes and fewer adverse effects from alcohol than lower-SES subjects supposedly consuming similar amounts. One potential explanation for this has been that higher SES subjects (those with higher education, income, job status, etc.) are more likely to be regular moderate drinkers, more likely to be wine drinkers, and to drink primarily with meals, while lower SES subjects are more likely to binge drink (mainly beer or spirits), not with food, and may tend to under-report their alcohol intake. However, there are limited scientific data on the specific mechanisms by which such differences occur.
The authors of the present paper have used data on alcohol intake collected in the Scottish Health Surveys from more than 50,000 subjects to investigate whether the harmful effects of alcohol differ by socioeconomic status when accounting for a number of SES factors. They had very good measures of SES based on education, income, social class (professionals, skilled manual labor, unskilled labor, etc.), and a “measure of deprivation” of the geographic area of the subject (based on multiple measures of deprivation from government administrative data). Their health outcome measures were based on public records for deaths, admissions, and prescriptions; their primary outcome was alcohol-attributable admission or death. Their data show that, even without considering alcohol consumption, lower SES subjects were at much greater risk for poor health outcomes. And, while risks associated with increasing amounts of alcohol were present in all SES groups, they were much greater in the lower groups.
Forum members considered this to be a well-done study, but pointed out that there was limited information on the pattern of drinking and no data on the type of alcoholic beverage consumed or whether or not it was consumed with food. There was no dietary information or genetic information available, and little data on access to health care. While the study showed very marked differences in adverse health outcomes according to SES, the authors found that the factors they considered explained little of the health effects seen. They concluded: “Disadvantaged social groups have greater alcohol-attributable harms compared with individuals from advantaged areas for given levels of alcohol consumption, even after accounting for different drinking patterns, obesity, and smoking status at the individual level.”
Forum members agree that there may be many other lifestyle factors associated with poverty that scientists are unaware of, or unable to adequately control for, in their analyses. Differences by SES in the assessment of alcohol intake remains as a potential factor (especially given that higher SES subjects are usually found to consume alcohol regularly and moderately, less in binges, more often consuming wine with food, etc.). The authors of the present paper have evaluated a number of factors (including smoking status and obesity) as potential explanations for the poorer outcomes among lower SES subjects, and still found large differences in health effects despite adjusting for a number of such lifestyle factors. Thus, the specific reasons why lower SES subjects have worse health overall and poorer effects after alcohol consumption remain unclear.
Reference: Katikireddi SV, Whitley E, Lewsey J, Gray L, Leyland AH. Socioeconomic status as an effect modifier of alcohol consumption and harm: analysis of linked cohort data. Lancet Public Health 2017. Online publication May 10, 2017. http://dx.doi.org/10.1016/S2468-2667(17)30078-6