The link between per capita alcohol consumption and alcohol‐related harm in educational groups
Introduction and Aims
There is a large body of research documenting a strong link between various forms of alcohol‐related harm rates and per capita alcohol consumption.
The relation between per capita alcohol consumption and a large number of outcomes thus seems to be well substantiated in studies of the general population.
However, an important issue is whether the relation is valid also across various sub‐populations, for example with different socioeconomic status (SES) – which is the focus of the present study. One reason for why this cannot be taken for granted is that SES‐groups may differ in their vulnerability to alcohol (usually referred to as differential vulnerability). This refers to the notion that lower SES‐groups tend to be more susceptible to the negative effects of alcohol and builds on the alcohol harm paradox, that is the observation that less privileged groups experience a disproportionally large share of alcohol‐related harm, although they tend to consume less alcohol, or at least not more, than other social strata.
Research based on individual‐level data suggests that the same amount of alcohol yields more harm in low‐socioeconomic status (SES) groups than in high‐SES groups. Little is known whether the effect of changes in population‐level alcohol consumption on harm rates differs by SES‐groups.
The aim of this study was to elucidate this issue by estimating the association between per capita alcohol consumption and SES‐specific rates of alcohol‐related mortality.
Design and Methods
Per capita alcohol consumption was proxied by Systembolaget’s alcohol sales (litres 100% alcohol per capita 15+).
Quarterly data on mortality and alcohol consumption spanned the period 1991 Q1 – 2017 Q4.
The researchers used two outcomes:
- alcohol‐specific mortality (deaths with an explicit alcohol diagnosis); and
- violent deaths.
SES was measured by education.
The researchers used three educational groups:
- low (<10 years);
- intermediate (10–12 years); and
- high (13+ years).
The researchers applied error correction modelling to estimate the association between alcohol and alcohol‐specific mortality, and seasonal autoregressive integrated moving average‐modelling to estimate the association between alcohol and violent deaths.
The estimated associations between per capita consumption and the two outcomes were positive and statistically significant in the two groups with low and intermediate education, but not in the high education group.
The SES‐gradient is especially strong for alcohol‐specific mortality
There was a significant gradient in the level of association between alcohol consumption and alcohol‐related harm by educational group; the association was stronger the lower the educational group.
Numerous studies suggest the presence of The Alcohol Harm Paradox, that is, that the same amount of alcohol gives rise to more harm in low‐SES groups than in high‐SES groups. No study has examined whether a corresponding phenomenon exists also at the population level.
The study’s findings, based on Swedish quarterly data, spanning the period 1991 to 2017, suggests that this is indeed the case.
The researchers found a statistically significant SES‐gradient in the alcohol effect on alcohol‐specific mortality and violent deaths; that is, a 1‐l increase in per capita consumption was associated with more alcohol‐related deaths (in absolute terms) in the low‐educated group than in the high‐educated group.
These findings suggest that the association between per capita consumption and alcohol‐related harm was stronger the lower the educational group.
There may be two, not mutually exclusive, explanations of this pattern of findings:
- differential relations between consumption level and risk of harm; and
- differential consumption changes.
The research findings that alcohol‐related harm rates are affected by changes in total alcohol consumption have provided a strong argument for maintaining a restrictive alcohol policy.
The present study adds a socioeconomic dimension to the understanding of the population level association between alcohol and related harm by revealing a social gradient in the alcohol effect implying that an increase in per capita consumption is associated with a larger increase in alcohol‐related mortality in the low‐educated groups than in the high‐educated group.
Moreover, we found a substantial social gradient in alcohol‐specific mortality, with rates that were around six times higher in the low compared to the high‐educational group. This finding is line with previous research showing that the social gradient in alcohol‐attributable mortality tends to be larger than for other major health outcomes, for example all‐cause mortality.
Considering the increased emphasis on decreasing social inequality in ill‐health, including alcohol‐related harm, it becomes increasingly important to explore which alcohol policy measures are effective for reducing or preventing social inequalities. The study’s findings indicate that population‐based policy measures that effectively regulate per capita alcohol consumption, not only will result in decreased rates of alcohol‐related harm, but also have the potential to narrow the large social inequalities of this outcome.