This study was the first to quantify alcohol-attributable mortality in South Africa by SES, thereby adding an important dimension to previous analyses of mortality and health burden associated with alcohol use [
14,
41]. Furthermore, this study included deaths from HIV/AIDS, which has not been taken into account in previous analyses.
As expected, a lower SES was associated with a clearly elevated mortality rate from alcohol-attributable causes of death. Given the distribution of the race groups across socioeconomic strata, the elevated mortality burden in the low and middle SES groups was largely experienced by black African as well as other non-white population groups.
For deaths from infectious diseases such as HIV/AIDS, tuberculosis, and lower respiratory infections, the socioeconomic differences in the alcohol-attributable mortality rates were particularly wide. These findings are in line with the results of a recent review and meta-analysis investigating the associations between alcohol-attributable morbidity and mortality and SES [
42]. Further, a recent study from South Africa also found a higher contribution of alcohol use to socioeconomic differences for self-reported diagnoses of tuberculosis and a relatively lower contribution to diagnoses of diabetes, stroke, or cancer [
43].
AAFs were overall elevated for people of low and middle SES, particularly among men. The socioeconomic differences were much less pronounced (and even inverted among women) in the youngest age group (15–34 years). This reflected more similar drinking patterns between persons of low, middle, and high SES in younger ages. Overall, the elevated AAFs for persons of low and middle SES arose from the higher prevalence of binge drinking and higher levels of alcohol use as compared to the prevalence of current drinking per se. The latter was consistently higher among people of high SES. The findings regarding the SES distribution of drinking patterns were in line with other recent evidence from South Africa [
9].
Previous research using individual data on SES, exposure to alcohol use, and cause-specific morbidity or mortality showed that persons of lower SES carry a higher risk for alcohol-attributable harm even after adjusting for patterns of alcohol use [
44] as well as other risk behavior [
45]. The phenomenon that persons of lower SES often carry a higher health burden despite lower levels of alcohol consumption [
46‐
49] has become known as the ‘alcohol harm paradox’ [
50]. As SES-specific risk functions were not taken into account in the present study (with the exception of HIV/AIDS for which interaction effects between SES and alcohol use were accounted for [
25,
26]), the reported estimates can, overall, be seen as conservative with respect to the socioeconomic differences in AAFs.
The estimate of about one in ten deaths being attributable to alcohol in South Africa in 2015 was higher than the estimate from a previous analysis from South Africa (~7% of all deaths in 2000) [
14] as well as the current estimate of the Global Burden of Disease study (~6% of all deaths in 2015) [
41]. This can be explained by the inclusion of additional causes of death, most prominently HIV/AIDS, as well as the use of a mortality envelope (i.e., deaths from all risk factors have to add up to the total deaths observed) in the Global Burden of Disease study.
Strengths and limitations
This study applied a rigorous methodology using the most up to date data available to estimate nationally representative alcohol-attributable mortality rates for all major causes of death known to be causally attributable to alcohol use by age, sex, and SES.
A main limitation of the study relates to the assessment of alcohol exposure in each sociodemographic subgroup. Even though binge drinking and heavy alcohol use are known to be highly prevalent in South Africa [
51‐
53], estimates of over 60 g of pure alcohol per day, on average, are very high. The high levels of consumption among current drinkers could have resulted from a low coverage of alcohol use that has been observed for all major, nationally representative surveys in South Africa in recent years [
36]. The triangulation technique, used to estimate the ‘true’ exposure to alcohol, relied on nationally representative estimates of the prevalence of alcohol use in each subgroup and relative levels of alcohol use between subgroups [
37]. Consequently, a underestimation of the prevalence of current alcohol use based on the survey data could have led to an overestimation of the levels of alcohol use among current drinkers.
Underreporting and denial of alcohol use due to stigma or memory bias, a high prevalence of heavy and irregular drinking patterns, systematic non-observation of heavy alcohol use due to the sampling frame, and selective non-response were identified as potential causes of the low coverage [
54‐
58]. Recent research estimated that 93% of the alcohol used in Pretoria, South Africa, was consumed in heavy drinking occasions, a drinking pattern that likely contributed to the low coverage [
59]. The latter study also used a much more elaborate assessment of alcohol use, which led to considerably higher levels of consumption among current drinkers compared to the assessment in large nationally representative surveys [
53].
As a consequence of the low coverage, AAFs could have been overestimated for some causes of death such as cardiovascular diseases [
60], liver cirrhosis [
61], or pancreatitis [
62], with risk functions that are sensitive to high levels of consumption. At the same time, the potential underestimation of the prevalence of current alcohol use could have led to an underestimation of AAFs for causes of death with flatter risk curves and an elevated risk at low levels of consumption such as cancers [
63] or lower respiratory infections [
64].
As nationally representative cause of death data including reliable information on the SES of the deceased are not available, HRs were used to split the deaths into the three SES groups. Using the projected asset score relied on the assumption that the population of the DSA was representative of the rural and periurban population in Kwazulu-Natal as assessed in the nationally representative survey.
The HRs used for splitting deaths by SES were not age and sex specific, but rather adjusted for age and sex. However, previous studies did not find systematic sex differences in the socioeconomic gradients of cause-specific mortality that could have led to an over- or underestimation of deaths in a specific sociodemographic group [
65].
Uncertainty of all estimates was estimated using a Monte Carlo approach. While this is in line with current standards, the intervals depend on the assumed distributions. An alternative approach for future research could be a systematic analysis of the variation in the resulting point estimates when using plausible extreme values of the lowest level parameters similar to a Latin Hypercube approach [
66].
Implications
There are a series of effective policy measures to prevent alcohol-attributable harm such as limitations of availability and affordability of alcohol, restrictions of alcohol-marketing, and improvement of the healthcare system [
67‐
69]. However, such broad brushed measures might fail to address the causes of death found to be most relevant as well as the high risk groups identified in the current study.
When considering alcohol policies in South Africa, it should be taken into account that approximately 23% of the total alcohol consumed in South Africa in 2015 was unrecorded [
70]. It is likely that the lion’s share of unrecorded alcohol is consumed by people of lower SES [
71]. This means that policies and interventions targeting the consumption of unrecorded alcohol might be more suitable for reducing alcohol-attributable harm in people of low SES than the national alcohol policies listed above. Furthermore, policies could address drinking venues frequented by people of low SES, such as unlicensed alcohol outlets, also called
shebeens [
72]. Even when selling recorded alcohol,
shebeens often operate outside the legal market, and policy measures to restrict availability and hours of sales do not reach unlicensed
shebeens or their customers.
There have been attempts to integrate
shebeens into the legal market; however, the owners are often not able to afford license fees and related taxes or apply the required changes to adhere to the guidelines or they are situated in areas not zoned for business use [
73,
74]. The current political strategy seems to focus on police raids, confiscations of liquor, and closing down of unlicensed outlets [
73,
74]. However, this practice fails to acknowledge the economic and social importance
shebeens have for owners and customers [
72]. Drivdal and Lawhon [
74] proposed a plural regulation of
shebeens based on a concerted effort of community leaders,
shebeen owners, and residents, which could be the first step towards enforcement of closing hours, prevention of sales to minors and intoxicated people, and reduction of violence in and around
shebeens [
75].
Targeted interventions on HIV transmissions under the influence of alcohol are another approach to prevent alcohol-attributable mortality and related socioeconomic differences. Alcohol-related HIV risk-reduction interventions, targeted at drinkers in under-resourced areas, have been shown to be effective in reducing unprotected intercourse under the influence of alcohol [
76]. Alternatively, HIV/AIDS risk reduction counseling and brief interventions could be targeted at drinkers in sexually transmitted infections clinics and more broadly in primary healthcare clinics and trauma units [
77].
Apart from interventions that address alcohol use and drinking environments of people of low SES, socioeconomic differences can be addressed on a structural level [
4]. Healthy communities require living environments with affordable housing, clean water, sanitation and electricity, infrastructure and public transit, access to education and healthcare, and safe opportunities to spend leisure time [
78,
79]. Marmot et al. suggested that “
health and health equity might not be the aim of all social and economic policies, but they will be a fundamental result” ([
79], p. 1661). Therefore, all policies should be evaluated with respect to their potential effects on health and its respective inequalities.