Table 3.

Thematic table of explanations for the AHP extracted from included papers with information on type of study design and population.

Domain	Theme	Explanation	Definition	Study design	Population
Individual	Biological	Biological characteristics [3,34,40]	SEP groups have a different biological or genetic make-up related to ethnicity or due to experiencing inequality which leaves them more susceptible to harm	Systematic review, discussion paper, cohort	General population
		Behavioural-related alterations [21,40,46,85,102]	Engaging in multiple risk behaviours has a biological impact: (i) nutritional deficiencies and metabolic consequences which alter protein and vitamin absorption, (ii) an adverse effect on the immune system and (iii) they interact with live enzymes, all leading to greater risk of disease (e.g. liver disease) and harm	Cross-sectional, cohort, commentary, report	General population
	Psychological	Stress [3,4,34,46,52,76,81]	Low SEP groups experience more psychological stress and a greater number of stressful events: (e.g. marital breakdown, dangerous environment, immigrant status, unemployment and living in poverty). This is thought to reduce resilience to disease	Systematic review, cohort, discussion paper, meta-analysis, cross-sectional	General population
		Coping [8,30,33,34,42,52,56,58,78,80,88,89,93,98]	Differences in coping strategies: low SEP groups use alcohol as a coping strategy which can lead to alcohol dependence. They are also more likely to use resigned acceptance as a coping strategy and are less likely to use cognitive avoidance and emotional discharge which independently negatively impact wellbeing	Cross-sectional, discussion paper, cohort, qualitative	General population, men, young people, military conscripts, patient
		Stereotypes/stigma [61,80,81,88,89,96]	Lower SEP groups experience more labelling and discrediting which leads to social rejection and exclusion. This could result in a self-fulfilling prophecy, whereby members of that group enact the behaviours they are expected to possess. This could also increase group and individual tensions which find an outlet via harmful drinking. This may also lead to fewer social resources, increasing psychological vulnerability	Discussion paper, cross-sectional, cohort, review	General population
		Attribution [8,83]	There are a higher number of abstainers in low SEP groups, therefore the alcohol problems faced by those who do drink in this group may seem worse by comparison. This only holds true for subjective measures of alcohol-related harm	Cross-sectional	General population
	Health and wellbeing	Physical health [8,9,32,34,35,41,47,62,63,74,76,93,94,96,98]	There is a higher prevalence of pre-existing physical health conditions, poorer general health, multi-morbidities or being overweight/obese in low SEP groups which could explain disproportionate effects of alcohol	Cross-sectional, cohort, review, case–control, meta-analysis, qualitative, report	General population, patient, men, adults with long-term conditions
		Mental health [8,22,34,41,47,48,50,53,63,76,93,96,98]	Low SEP individuals tend to be more psychologically vulnerable and have a greater prevalence of pre-existing mental health conditions, mental distress, or psychological symptoms (e.g. nervousness, irritability, helplessness, loneliness) which could exacerbate the effects of alcohol. There is also an independent association between poor wellbeing and worse health outcomes	Cross-sectional, review, cohort, report, meta-analysis, qualitative	General population, patient, adults with long-term conditions, young adults
Life-style	Risk behaviour	Drinking patterns [1,3,4,8,10,14,18,21,22,30,32,34,39,41,45–47,49,51–54,59,60,62–64,71,73,79,81,83,85,86,91,94,95,98–100,103]	Although overall or average alcohol consumption may be similar, or lower for low SEP groups, they consume greater quantities of alcohol per drinking occasion	report, systematic review, meta-analysis, cross-sectional, cohort, review, commentary, discussion paper	General population, men, patient, young adults
		Clustering of health behaviours [3,4,10,18,21,22,37,40–44,46,47,53,59,63,64,72,74,76,81,90,95,103]	Those in low SEP groups engage in multiple health risk behaviours for example smoking, poor diet, a lack of exercise and concurrent drug use which exacerbate the impact of alcohol	Systematic review, meta-analysis, cross-sectional, cohort, case–control, report, discussion paper	General population, adults with long-term conditions, young adults, male patients, patient
		Type of beverage [4,10,18,21,32,47,86,90,93,102]	Beers, ciders and spirits are more commonly consumed by low SEP, while wine is often associated with higher SEP. The quality and price of alcohol consumed may impact harm outcomes	Cohort, systematic review, meta-analysis, cross-sectional, commentary, qualitative, report	General population, patient
		Drinking history/future drinking [4,21,22,60,62,77,103]	Drinking is temporal and may change throughout the life-course. Although those of low SEP may have reduced consumption upon measurement, increased susceptibility to harm could be due to previous drinking. There are several reasons why people may reduce consumption (e.g. developing an illness). This explanation was extended to an increase in consumption in the future, as some studies only measure consumption at baseline and outcomes in following years	Cohort, cross-sectional, commentary, report	General population, men
	Drinking practices	Norms [51,53,75,78,85,87,92,96,101]	Group and neighbourhood norms including drinking pattern, expected volume, how to drink certain beverages (e.g. shot a spirit) and norms around the permissibility of excessive alcohol use differs by SEP	Cohort, report, qualitative, review	Young adults, patient
		Culture [75,78,88,96]	Drinking culture attached to certain places of employment or neighbourhoods may lead to poorer health and difficulties maintaining employment, which could then exacerbate stress and increase consumption	Report, qualitative, cohort, review	Young adults, general population
	Health-consciousness	Health literacy [21,37,77,93,94,97]	Engagement with health promotion campaigns and preventative services. It was proposed that low SEP may not make use of available services or are slower to access these services	Cross-sectional, cohort, commentary, qualitative, report	General population, patient, men
		Healthy behaviours [9,34,37,76,85]	Those of a high SEP adopt healthy behaviours (e.g. good diet and exercise) which may protect against negative impacts of drinking	Cohort, review, meta-analysis, commentary	General population
Contextual	Social	Social support [9,18,34,35,45,51–53,55,73,75,76,89,93,96,101–103]	Social support may buffer the negative impacts of alcohol consumption. Those of high SEP have a wider ‘social margin’ which insulates them from the negative consequences of their actions while low SEP lack social support and are often socially isolated	Systematic review, meta-analysis, report, cross-sectional, review, cohort	General population, young adults
		Social exclusion [1,75,76,88,96]	The marginalization of low SEP groups is greater due to several factors including a higher number of abstainers, stigmatization that comes with having an alcohol use disorder and intersections between multiple minority status (e.g. ethnic, refugee, homeless and LGBT+)	Report, meta-analysis, cohort, review	General population
		Peer influence [9,53,75,96,101,102]	Negative influence from peers and family in low SEP groups may impact harm outcomes. There is evidence that men of high SEP are more likely to be married and therefore long-term partners may be an important agent of social control for excessive drinking. Not only would a partner provide social control but also additional financial support via combined income and this influence was extended to others in their social network	Cohort, report, review	General population
	Drinking context	Dangerous environment [1,9,18,36,48–50,78,84,98,102]	Low SEP are more likely to drink in dangerous environments with a lack of policing and safety, which may lead to a higher risk of violence, police encounters and unintentional injury	Report, systematic review, meta-analysis, cohort, discussion paper, cross-sectional, qualitative, commentary	General population, young adults, patient
		Exposure [102]	Drinking in public places is common among the most deprived groups (e.g. the homeless). This leaves them exposed to certain infectious diseases (e.g. TB and HIV) which may compound harm	Report	NA
	Place	Neighbourhood deprivation [10,18,44,46,50,53,79,81,84,89,102]	A lack of resources, treatment facilities or preventative/educational programs, an increased police presence, neighbourhood disorder, low educational ethos and a lack of community institution negatively impact harm outcomes	Systematic review, meta-analysis, cross-sectional, report, case–control, cohort, commentary	General population, patient, young adults
		Alcohol outlet/advertising density [3,53,54,59,71,75,81,87,89,96,102]	Increased outlet density has an impact on patterns of drinking and harmful consequences. The density of alcohol advertising in deprived areas was also considered to potentially influence the excess harm experienced by those of a low SEP	Systematic review, report, cross-sectional, cohort, commentary, review	General population
Disadvantage	Intersectionality	Multiple minorities [44,52,76,80,81,92,96,101]	The impact of belonging to multiple minority groups (e.g. SEP, race, gender, and sexuality), and how experiencing multiple aspects of disadvantage may amplify inequalities in alcohol-related harm	Case–control, cohort, meta-analysis, cross-sectional, review, report	Patient, general population
	Life-course	Cumulative effects [9,37,44,52,55,58,74,84,96,102]	The accumulation of negative/stressful life events over time or additive effects of prolonged risky health behaviours which negatively impacts health and potentially employment itself	Cohort, case–control, commentary, review, report	General population, patient, military conscripts
		Early risk factors [9,50,55,58,75,96,103]	The experience of ACE’s in childhood, childhood household dysfunction and a disadvantaged start in life (including prenatal factors) perpetuates a vicious cycle of poverty and poor health which impacts on social participation, wellbeing, their ability to cope and access to available support or treatment	Cohort, cross-sectional, report, review	General population, young adults, military conscripts
		Family influence [55,81,102]	Limited family income restricts material resources and creates stress given the inability to meet basic needs. Family history of alcohol problems could impact alcohol consumption and health in later life. Parental education is shown to negatively impact on health literacy and children’s employment aspirations, opportunities, and adulthood income	Cohort, cross-sectional, report	General population
	Material	Material resources [1,4,14,49,51,55,73,74,93,96]	A lack of resources could negatively impact on harm due to the inability to protect themselves from the experience of a problem or stressful life event and could exacerbate poor health through poor housing conditions, homelessness, and unemployment	Report, cohort, cross-sectional, case–control, qualitative, review	General population, young adults, patient
	Neo-materialist	Access, quality and barriers [1,3,10,14,18,21,38,44,46,52,53,55,64,75,76,87,93,96,98,102,103]	Depending on geographical distribution, services in disadvantaged areas may be fewer and more difficult to access or of a lower quality. Low SEP groups face several potential barriers when attempting to access health-care including cost, transport, availability (in terms of opening hours), mobility issues and stigma which may deter them from using services. Dependent on country there were additional considerations for example the cost of health insurance	Report, systematic review, cohort, meta-analysis, qualitative, review, cross-sectional, case–control	General population, patient
Upstream	Structural	Economic [1,16,33,45,53,56,75,87,96,97,102]	Trickle-down effects of the economy were thought to contribute to excess harm. Economic stressors (e.g. economic downturns or recession) are more closely associated with morality in the lowest SEP groups. Gross national income and changes in minimum or disposable income has increased the buying power of low SEP groups, which has led to an equalization of alcohol consumption	Report, review, cross-sectional, cohort	General population
		Socio-political [38,44,46,75,80,84,96]	The attitudes and decision making of residents and policymakers. Politicians focusing on individual behaviours rather than tackling the social determinants of health which increases inequalities. Political context is extremely important, as countries with poor minimum living standards, limited public investment in social goods (particularly in deprived areas) and worse social system responses are likely to worsen health outcomes for low SEP groups	Cross-sectional, case–control, cohort, report, commentary, review	General population, patient
		Alcohol policy [41,61,75,87,96]	The mutually beneficial economic relationship between the state and the alcohol industry shapes policy decisions. Although it is hoped that this is counterbalanced by ‘helping professions’ it is also in their interest to continue the expansion of treatment and this is deflected by each entity casting blame on the another. Additionally, a lack of policy that aims to reduce harmful consumption, alcohol availability, pricing and promotion, and global market liberalization (changes in affordability), production, importation, distribution, and pricing of alcohol were hypothesized to contribute to the AHP	Cohort, discussion paper, report, review	Adults with long-term conditions
		Corporate influence [61]	The alcohol industry funds alcohol research which may misinform policy decision-making. Privately owned media was also argued to play a role via diffusing true or false information	Discussion paper	NA
		Employment [9,14,43,52,74,75,81,96]	There were several mechanisms through which employment could worsen alcohol-related harms for low SEP groups. This included the working conditions or occupational exposures faced by low SEP individuals. Job type, low wages and inflexible employment, and job alienation, stress and low satisfaction are all thought to negatively impact harm outcomes. Those from more deprived backgrounds with insecure employment may also be less able to take time off work when they become ill, compounding the problem. This contrasts with the idea that high SEP individuals may get more support from their employers, whereby employers are more willing to invest energy in solving their alcohol problems. Relatedly issues of unemployment were also discussed including the issue of receiving additional help of benefits related to a long-term condition or disability which may discourage some people from getting better as they would lose this additional help as a result	Cohort, report, case–control, cross-sectional, review	General population, male patients
		Power [61]	Dominant groups in society may suppress subordinate groups via different means (e.g. variable wages, segmented social status), therefore fragmenting groups. These subgroups would then experience greater discrimination and stigma, while the status quo is maintained by the dominant groups having individualistic beliefs. This coupled with social control: the idea that the most powerful individuals have an interest in subordinate groups adopting deviant or socially problematic behaviour which in turn is defined by the powerful, facilitates a ‘revolving door’ system by which the same individuals pass through a multitude of institutions including hospitals, jails, and clinics	Discussion paper	NA
		Broad determinants [45,46,85,90]	Other broad factors, such as social and commercial determinants of health, are the causal factors associated with low SEP which may explain the AHP	Cohort, commentary	General population
Artefact	Downward drift	Reverse causation [1,4,21,45,53,57,74,81,85]	Heavier drinkers are more likely to lose their job or move to deprived areas due to their heavy drinking. The existence of an alcohol problem is the driving force behind low SEP, rather than low SEP having an independent association with increased harm	Report, cross-sectional, cohort, report, case–control, commentary	General population
	Methodological	Under-reporting/measurement error [3,14,42,44,47,59,60,64,71,74,90,94,103]	The use of self-report measures allows the opportunity for response bias and memory limitation to impact the results. Measures which rely on binge drinking beyond a threshold instead of individual units is not accurate at capturing differences in the proportions of non-drinkers between SEP groups	Systematic review, meta-analysis, report, cohort, case–control, cross-sectional, commentary	Young adults, patient, general population
		Unmeasured factors [44]	Not all confounders are measured. For example, the way cigarette smoke is inhaled or the type of cigarette could have an impact on harm	Case–control	Patient
		Study Design [46]	Need to use more longitudinal data when investigating the AHP particularly to account for time-dependent effects	Cohort	General population
		Under-representation [3,14,21,85,94]	The heaviest drinkers in deprived areas are often under-represented in studies. This is a potential confounder for cross-sectional studies using aggregate data, as once the heaviest drinkers are accounted for higher rates of harm are no longer paradoxical	Systematic review, meta-analysis, report, commentary	NA

SEP = socio-economic position; LGBT = lesbian, gay, bisexual, transgender; NA = not applicable; TB = tuberculosis.