A Prospective Analysis of the Interrelationship between Physical Intimate Partner Violence and Alcohol Use: A Post-Hoc Analysis of Young Women Involved in the Stepping Stones and Creating Futures Trial in South Africa

Reducing harmful alcohol use and intimate partner violence (IPV) are both targets of the Sustainable Development Goals (SDG) (SDG 3.5 alcohol and SDG 5.2 IPV), as individually and together these have multiple negative impacts on health and development (Degenhardt et al., 2018; Ellsberg et al., 2008). In South Africa, high rates of both IPV and alcohol misuse have been reported (Davis et al., 2017; Machisa et al., 2011; Norman et al., 2010; Peltzer et al., 2011). This is particularly the case in urban informal settlements where overlapping factors of poverty, limited state support and engagement, sparse social networks, gender inequalities and generalised community violence have led to a particularly acute confluence of IPV and harmful alcohol use (Davis et al., 2017; Gibbs et al., 2018; Ndungu et al., 2020; Zembe et al., 2013). These two public health issues may have a syndemic relationship, whereby they overlap with one another, as well as being mutually reinforcing (Gilbert et al., 2015).

There is consistent evidence from high-income countries on the relationship between women’s experience of IPV and subsequent increases in alcohol use. A recent systematic review exploring the health impacts of IPV identified 10 longitudinal studies all showing positive relationships (Bacchus et al., 2018). Eight studies were from the USA and two further studies were from New Zealand (Bacchus et al., 2018). More recent research from high-income settings yielded similar findings. In Australia, a 9-year study found that women who experienced IPV by age 21 had significantly more alcohol use disorders, across a range of different forms of IPV during the follow-up period (Ahmadabadi et al., 2019).

There is mixed evidence on the impact of women’s alcohol use as a potential driver of experience of IPV, and all prospective studies are from high-income countries. An early systematic review and meta-analysis on three prospective studies from high-income countries found a significant positive association between alcohol use and subsequent experience of IPV (Devries et al., 2014). A more recent meta-analysis found seven longitudinal studies and presented two meta-analyses, where alcohol was treated as either a continuous or binary exposure variable (Bacchus et al., 2018). These meta-analyses found that while alcohol was associated with an increase in experience of IPV, this association was not statistically significant (Bacchus et al., 2018). In low- and middle-income countries, some existing evidence shows a significant relationship between alcohol and IPV (Davis et al., 2017; Greene et al., 2017; Russell et al., 2014), but none of these analyses are prospective.

In low- and middle-income countries, patterns of alcohol use, and the relationships between alcohol use and IPV, may differ from high-income countries. In some settings, alcohol use among women is limited, and this may be particularly true where social norms look unfavourably on young women’s drinking (Hlomani-Nyawasha et al., 2020; Sommer et al., 2019). Additionally, it may be that women tend to consume alcohol only if male partners are paying, given the high levels of poverty and reliance on men for survival (Zembe et al., 2013). Many low- and middle-income countries have high rates of community violence, and thus high prevalence unresolved trauma (McDonald & Richmond, 2008; Mmari et al., 2014), which may increase background rates of substance use, and thereby dilute or wash out any relationship between alcohol with IPV. It is therefore critical to expand the global evidence base on the relationships between alcohol and IPV to lower- and middle-income countries.

There has been substantial research on the inter-relationship between alcohol and IPV in South Africa. Broadly, South Africa has high rates of alcohol related harm, with the cost of alcohol harm estimated at 10–12% of Gross Domestic Product (GDP) (Matzopoulos et al., 2014). Many cross-sectional studies have highlighted the association between alcohol and women’s experiences of violence (Minnis et al., 2015; Ndungu et al., 2020; Pitpitan et al., 2013; Selin et al., 2019). Qualitative studies have emphasised how the centrality of informal drinking establishments (shebeens) in shaping the relationship between alcohol and IPV (Wojcicki, 2002; Zembe et al., 2013), as well as how alcohol becomes embedded in everyday conflict in intimate relationships (Backe et al., 2021), and how these are experiences are patterned by broader issues of poverty, and gendered expectations in relationships (Zembe et al., 2013).

To address the paucity of research on the temporal relationship between women’s use alcohol and experience of IPV outside high-income countries, we conducted a post-hoc longitudinal analysis of data collected as part of a cluster randomised controlled trial of the Stepping Stones and Creating Futures programme in urban informal settlements in South Africa (Gibbs et al., 2017). The primary aim of the main trial was to assess the effectiveness of the intervention in preventing IPV over a 24-month follow-up (Gibbs et al., 2020); alcohol use was included as a secondary outcome. The intervention did not impact either outcome for women. In the analyses presented here, we first examine whether changes in women’s experience of past-year physical IPV between baseline and endline has an effect on alcohol use at endline. Second, we look at whether changes in women’s alcohol use between baseline and endline impacted their experience of physical IPV in the past 12 months as reported at endline.

The study received ethical approval from the South African Medical Research Council’s Ethics Committee and the Biomedical Research Ethics Committee at the University of KwaZulu-Natal. All participants provided written informed consent prior to participation, and local community leadership provided letters of support.

At baseline, 677 women were enrolled in the study, with overall retention of 80.5% (n = 545) at 24 months. The 545 women who provided data at both timepoints, had a mean age 24.0 years at baseline, two-thirds (67.3%) had a current relationship, but did not live with their partner and a fifth (18.2%) reported no current relationship (Table 2). Half reported moderate food insecurity and nearly a third (30.5%) severe food insecurity, while only a quarter (25.1%) had worked in the past month. Three-quarters (77.6%) reported past year emotional IPV experience, half reported past year economic IPV experience and 28.1% past year sexual IPV experience. Nearly half (44.6%) scored with likely depression on the CES-D, and a fifth (19.6%) scored with potential PTSD. At baseline over half (58.5%) reported past year physical IPV and a quarter (23.9%) past year problem alcohol use. At 24 months, there were only slight changes, with slightly improving food insecurity (from severe to moderate), an increase in past month work, a borderline increase in economic IPV experience and an increase in depressive symptoms.

Supplementary Table 1 shows LTFU in the overall sample. Baseline characteristics associated with LTFU were being in the intervention group, being married or living with partner and higher mean relationship control scores. Supplementary Table 2 shows baseline and endline factors associated with missing data on the AUDIT score data at 24 months. Baseline characteristics associated with this were greater food insecurity, problem drinking and probable depression and PTSD. Endline characteristics associated with missing alcohol data were greater food insecurity, probable depression, PTSD and higher mean scores of controlling behaviour and we tested these as potential confounders, including in models those which impacted on the outcome models.

In a sample of young women living in urban informal settlements in eThekwini Municipality, South Africa, facing multiple overlapping challenges of poverty, high levels of background violence and limited social and state support, there was a clear and consistent finding whereby women who experienced increasing amounts of physical violence from partners over time were more likely to subsequently report greater harmful alcohol use, and similarly, women reporting increasing alcohol use over time were more likely to report past year physical IPV at endline. There was no evidence that decreases in alcohol use were associated with reductions in physical IPV, or that reduced IPV experience led to decreased alcohol use.

Our analysis strongly supports the finding from high-income countries that women’s experience of physical IPV is a driver of their subsequent alcohol use (Bacchus et al., 2018; Devries et al., 2014), and extends the evidence base through locating this in urban informal settlements in South Africa. In urban informal settlements, access to social support, psychosocial care and health care in general is limited, as are availability and use of legal strategies to deal with violence in relationships. As such, it is highly likely that increased alcohol use in response to increasing IPV experience is a form of self-medication (Hawn et al., 2020; Kaysen et al., 2007). IPV experience is strongly associated with worse mental health outcomes, including depression and post-traumatic stress (Bacchus et al., 2018; Devries et al., 2013), and there is clear evidence that alcohol is often used to self-medicate for these unresolved mental health issues where formal care is unavailable (Hawn et al., 2020; Kaysen et al., 2007). This hypothesis, around self-medication, gains support from our analyses: when we included depressive symptoms in the model, the overall association between physical IPV increasing and alcohol use was clearly attenuated, although it remained significant. It is important that alcohol use and poor mental health are acknowledged to have similar underlying drivers, and that interventions actively address this. Similarly, interventions to address IPV, and especially those that support survivors and/or seek to prevent recurrence of IPV, should recognize the importance of addressing alcohol use and depression.

In this analysis there was also evidence that where women increased their alcohol use, they were more likely to experience physical IPV. Global evidence on this point has been varied, with prospective studies from high-income countries showing mixed outcomes (Bacchus et al., 2018; Devries et al., 2014), and current evidence from low- and middle-income countries being cross-sectional only. The potential pathways through which increasing alcohol use may increase women’s experience of IPV may include increased arguments with a partner, either because women’s alcohol use breaks social norms on women’s behaviour (Wechsberg et al., 2013) or because alcohol use increases disinhibition (Babor et al., 1983). In the UK, studies on couples’ use of substances and violence highlighted the importance of arguments about access to substances (though more often hard drugs) as a driver of violence (Gilchrist et al., 2019). Other analyses (Martino et al., 2005) have demonstrated a reciprocal relationship between violence and alcohol use, and it may be that in this cohort, young women’s increasing alcohol use and IPV experience tracked closely together, and we cannot clearly disentangle the exact relationship between these two.

There was no evidence that decreasing experience of physical IPV reduced alcohol use, or that reductions in alcohol use reduced subsequent IPV experience. The reason for the lack of association is unclear. For both physical IPV and alcohol use, the proportion of women in this study who reported a decrease was similar to, or greater than, the proportion reporting an increase, so it is unlikely to be a question of simple statistical power. It may be that there are other factors which jointly impact on both that were not meaningfully changing during this time period, for instance, food insecurity or generalized experiences of community level-violence and trauma. It may also be that the impact of decreasing IPV and/or alcohol on the cycles of reciprocal causality has a reduced effect size compared to the increases we did observe, or that any benefits of reduced IPV/alcohol only appear over a longer time horizon than our 24 months of follow-up. Additional research with longer follow-up and a greater number of observations will be needed to unpack these questions.

In both analyses, increasing depressive symptoms were associated with increased likelihood of physical IPV experience and harmful alcohol use at endline. While studies in high- and low-income settings have previously described the prospective association between depression and IPV experience (Devries et al., 2013; Tsai et al., 2016), there remains limited prospective evidence about the impact of depression on women’s experience of IPV and women’s alcohol use in low-income settings. Without adequate treatment and support for depression, alcohol may become a form of self-medication, particularly in contexts of ongoing trauma, often starting from early childhood.

This study has several limitations. The population self-selected into an intervention trial, and is thus not representative of the general population; however, it is unclear how this would affect associations. Furthermore, the population consisted entirely of young women who all self-identified as ‘Black’, and we assumed heterosexual relationships, thus limiting generalization further. All measures were self-reported, and this could have led to under-reporting of either IPV or alcohol use, which would likely attenuate the association between the two. In addition, we did not ask about male partners’ alcohol consumption at either timepoint; this is strongly associated with women’s IPV experience and women’s alcohol use, and should be included as a potential confounder in future research. While we modelled changes in both physical IPV and alcohol use, we could not model these as reciprocal relationships. In addition, as the two timepoints were approximately 24 months apart, there could have been changes at 12 months not captured in our measures (which were both past 12 months). It is unclear how this would have affected our analysis. There was missing data at 24 months on a primary outcome – alcohol use – caused by faults in cellphone software, which was associated with potential drivers of alcohol use. To address this limitation, we used multiple imputation to verify the main analysis, which showed consistency in the relationships. We also modelled the relationships in multiple ways, and these too showed the same associations as in our primary analysis. We also only examined the associations between alcohol and physical IPV, rather than multiple forms of IPV, as we wished to disentangle this specific relationship and there remains little clarity on how to model multiple different forms of often overlapping IPV experience simultaneously.

Our analysis has several important implications for effective interventions to address alcohol use and IPV experience among young women living in challenging contexts. First, efficacious interventions need to address alcohol use and IPV simultaneously, given that they clearly exacerbate one another. Second, reflecting other recent analyses on effective IPV prevention (Kerr-Wilson et al., 2020), our analysis suggests addressing alcohol and IPV together, is unlikely to be successful without also addressing other shared underlying causes of these two issues. While many effective alcohol reduction and IPV prevention interventions are strongly focussed on addressing poor mental health (Murray et al., 2020), poverty is also an important driver of both alcohol use and IPV experience and deserves attention (Lund et al., 2010). As such, in low-income settings, addressing multiple drivers of alcohol use and IPV, including structural drivers, is critical for an effective response. Third, women’s alcohol use often occurs with male partners (Greene et al., 2017), and it may be that women are more vulnerable to violence when drinking with partners (Wechsberg et al., 2013). There is some evidence that interventions addressing alcohol and IPV have stronger outcomes when they work with couples, rather than individual women (Minnis et al., 2015). In this population of young women in urban informal settlements, the concept of ‘couple’ may not resonate with their lived experiences, particularly as women do not often reside with male partners (Gibbs et al., 2018). Developing effective ways of working with couples on the interlinked issues of alcohol reduction and violence remains an important priority, but given the complex relationships young women often had (Willan et al., 2019), also how to address these issues for individuals. Fourth, the separation between IPV prevention and response strategies is not clear cut, with many prevention interventions preventing ongoing violence in relationships (Chatterji et al., 2020), and requiring significant focus on the residual traumas of violence manifested in alcohol use, and concurrent depression, needing to be a focus of interventions in highly traumatized populations. Broadly, therefore, addressing the interlinked issues of alcohol use and experience of IPV among young women with multiple overlapping risk factors needs to address the shared risk factors, as well as these two issues directly if they are likely to be successful.

We would like to thank the participants who provided their time and information. We also acknowledge the fieldwork team involved in the project and the team of researchers who also contributed to the main study.