The syndemic effects of intimate partner violence, substance use, and depression on HIV risk among Indonesian women who inject drugs: findings from the Women Speak Out study

Background: Women who inject drugs face vast disparities in health outcomes relative to their counterparts in the general population, most notably in HIV. Intimate partner violence (IPV) victimisation has a detrimental individual effect on women’s HIV risk behaviour. Furthermore, IPV often co-occurs with substance use and poor mental health among women in high-income countries, but little is known about the cumulative and interactive effects of these conditions on women’s HIV risk behaviour in low- and middle-income countries. This thesis applied an ecological approach guided primarily by syndemics theory to understand influences on women’s HIV behavioural outcomes. It examined associations and mechanisms linking IPV, substance use, and depression, with HIV sexual and injecting risk outcomes in the first quantitative study of Indonesian women who inject drugs, the Women Speak Out study. Methods: This study combined community-based participatory approaches and extensive formative research with quantitative survey methods. 731 women, ≥18 years of age, and injecting illicit drugs in the preceding year were recruited using respondent-driven sampling (RDS) from urban settings in Greater Jakarta and Bandung, Indonesia. Network characteristics of the sample were assessed using the RDS software package for Stata 14. Data were analysed using multivariate logistic regressions, marginal effects models, and interaction analyses on the additive and multiplicative scales. The study was conducted in collaboration with the Indonesian Drug User Network. Results: Paper 1: Past-year IPV victimisation doubled the odds of engaging in one or more sexual HIV risk behaviours. Several covariates were associated with higher odds of sexual risk behaviour: HIV-positive status, non-injection crystal methamphetamine (crystal meth) use, low educational attainment, younger age, and being single. Co-occurrence of psychological, physical and/or injurious, and sexual forms of IPV had cumulative effects: sexual risk behaviour was reported by 62% of women who did not experience any form of IPV, but increased to 89% among those exposed to all three forms. Paper 2: Past-year IPV elevated women’s odds of receptive syringe sharing. These effects remained after controlling for socio-demographic confounders. Two covariates, injecting illicit pharmaceuticals (vs heroin only) and housing instability and/or homelessness, remained associated with receptive syringe sharing in multivariate analyses. Paper 3: More than 1 in 4 women experienced concurrent IPV, depressive symptoms, and crystal meth use. All three exposures had independent negative effects on HIV sexual risk outcomes. The co-occurrence of all three factors produced a 4-fold increase in rates of survival sex work, 5-fold increase in STI symptomatology, and a 7-fold increase in inconsistent condom use. The joint effect of depressive symptoms and crystal meth use together was greater than the product of the estimated effects of each exposure alone on STI symptomatology, indicating an interaction on the multiplicative scale. Statistically-significant positive additive interaction was detected between IPV victimisation and crystal meth on inconsistent condom use; depression and crystal meth on STI symptomatology and on survival sex work; and IPV and depression on STI symptomatology and survival sex work. Conclusion: This thesis provides new evidence of the individual and cumulative effects of IPV, methamphetamine use, and depression on HIV risk outcomes among Indonesian women who inject drugs. The interaction analyses are the first to empirically test the assertion that these co-occurring conditions interact synergistically to increase drug-using women’s HIV risk. This thesis furthers our understanding of how syndemics function within women who inject drugs to produce health disparities, and contributes to the problem theory for HIV risk behaviour in this population. The findings of this study have great public health significance and important implications for future longitudinal research, interventions, and policy.