Research paperThe complex interplay of social networks, geography and HIV risk among Malaysian Drug Injectors: Results from respondent-driven sampling
Introduction
With over 36.7 million people infected worldwide and 1.1 million deaths in 2015 alone, the HIV pandemic is the one of the most significant public health challenges of the 21st century (Joint United Nations Programme on HIV/AIDS (UNAIDS), 2016). Many countries struggle with developing and implementing effective HIV prevention and treatment strategies that target high-risk and hidden populations, including people who inject drugs (PWID), sex workers, transgender women and men who have sex with men (MSM). Illicit drug use, in particular, has a profound effect on the global burden of disease: among the 12 million PWID globally (United Nations Office on Drugs and Crime (UNODC), 2016), injection drug use as a risk factor for HIV accounts for 2.1 million Disability Life Adjusted Years (DALYs) (Degenhardt and Hall, 2012, Degenhardt et al., 2013). Even in concentrated HIV epidemics, where total HIV prevalence in the population is <1%, effective prevention strategies are needed due to the salience of the “bridging ties” that create opportunities for HIV transmission from high-risk individuals to the lower-risk general population, increasing the odds that the HIV epidemic may become generalized (Doherty, Shiboski, Ellen, Adimora, & Padian, 2006).
Bio-behavioural surveillance studies are often used to assess HIV prevalence and risk-behaviours in high-risk, hidden populations, and typically rely on either respondent-driven sampling (RDS) or time-space venue-based sampling (Kendall et al., 2008; Magnani, Sabin, Saidel, & Heckathorn, 2005) recruitment strategies. Each method, however, is fraught with challenges that undermine its ability to represent the intended population. Such limitations include non-response and selection bias due to differential recruitment (Amber & Gile, 2011), homophily (Mills et al., 2012), variability in geographical location (Bazazi, Crawford et al., 2015, McCreesh et al., 2012, Toledo et al., 2011), and seed selection (i.e. who is initially recruited) (Heimer, 2005). Despite these methodological limitations, RDS remains a primary recruitment strategy for PWID by international public health authorities due to its efficiency in reaching hidden populations (Centers for Disease Control and Prevention, 2007, Goel and Salganik, 2010, Malekinejad et al., 2008).
Malaysia, a polycultural Southeast Asian country with a population of over 30 million, is home to an estimated 200,000 PWID, most of whom inject opioids (Bachireddy et al., 2011; United Nations Office on Drugs and Crime (UNODC), 2016). HIV was primarily concentrated in PWID and HIV prevention and treatment efforts first focused on the introduction of needle/syringe exchange programs (NSPs) and in 2006 opioid agonist therapies (OAT) with buprenorphine and methadone (Kamarulzaman, 2009; Reid, Kamarulzaman, & Sran, 2007). Though there is nascent evidence of an emerging transitional epidemic, including transmission from PWID to their heterosexual partners (Ministry of Health Malaysia, 2014; UNGASS, 2010), the majority of people living with HIV (PLH) are PWID. Yet, HIV prevention and treatment in Malaysia remains inadequately scaled to need (Degenhardt et al., 2014, Kamarulzaman, 2009) with preventive measures reaching only a small fraction of the most-at-risk populations (Reid et al., 2007). Based on recent 2013 surveillance data, Malaysia had a cumulative number of more than 100,000 HIV cases, including more than 85,000 PLH and more than 16,000 deaths related to HIV/AIDS (Ministry of Health Malaysia, 2014).
In 2010, we conducted a bio-behavioural surveillance study in greater Kuala Lumpur using RDS to recruit opioid-dependent PWID (Bazazi, Crawford et al., 2015, Bazazi, Zelenev et al., 2015). We analysed how the spatial proximity of PWID to their peer network, influence HIV status and HIV risk behaviours in order to: (a) inform improvements in sampling methods and (b) guide the discussion for designing more optimal prevention strategies. Previous studies have demonstrated the importance of networks (Friedman, Curtis, Neaigus, Jose, & Des Jarlais, 2002; Friedman et al., 1997; Latkin, Forman, Knowlton, & Sherman, 2003; Mustanski, Birkett, Kuhns, Latkin, & Muth, 2014; Rothenberg et al., 2000) for HIV transmission and geography for recruitment of populations most-at-risk for HIV (Jenness, Neaigus, Wendel, Gelpi-Acosta, & Hagan, 2014; Rothenberg, Muth, Malone, Potterat, & Woodhouse, 2005; Toledo et al., 2011), yet none of these studies have accounted for the influence of the network formation process, which can induce a non-causal pattern of observed correlations in the HIV outcomes. Findings from these analyses are relevant for future interventions that aim to target individuals most-at-risk and explore the potential for incorporating network, structural and spatial strategies in reducing HIV transmission.
Section snippets
Study design and recruitment
Recruitment methods have been previously described (Bazazi, Zelenev et al., 2015). In brief, from July to October in 2010, 460 PWID were recruited using RDS to examine a cross-sectional assessment of drug use behaviours, risk factors and health outcomes associated with drug use. Eligibility criteria included: (1) age ≥18 years; (2) residing in greater Kuala Lumpur; (3) drug injection in the previous 30 days, confirmed by physical examination of injection track marks and/or knowledge of drug
Geography of HIV and recruitment networks
Table 1 contains a summary of the sample. Most PWID were Malay men in their late 30’s, who on average injected 3 times per day, primarily with heroin. Most respondents had stable housing (82%) but were not involved in a stable relationship (69.3%). Compared to HIV-seronegatives, HIV-infected PWID were more likely to be homeless (31.5% vs 14.5%, p < 0.01), have more prior incarcerations (5.2 vs 3.4, p < 0.01), have fewer recent injection partners (2.4 vs 5.4, p < 0.01), be less likely to use clean
Discussion
Our analysis of the interaction between the first and second degree social ties and geographical distances, underscores how a compact geospatial area can increase the risk of HIV transmission by facilitating close contact between HIV-infected PWID. We demonstrated that there is a gradient to spatial proximity depending on the type of relationship (peer vs neighbour). An increase in physical distance between social acquaintances is associated with a decline in HIV transmission risk, while, all
Conclusions
The clustering of HIV infections across networks and space in Kuala Lumpur underscores the importance of closely integrating surveillance and prevention strategies. RDS can be applied to identify injection network structures and this provides an important mechanism for improving public health surveillance, accessing high-risk populations, and implementing risk-reduction interventions to slow HIV transmission.
Funding
This research was supported by NIH career development (K01 DA037826 for AZ, K24 DA017072 for FLA and F30 DA039716 for ARB), research (NIDA R01 DA025943 for FLA), and training (T32GM07205, T32MH020031 for ARB) grants as well as University of Malaya’s High Impact Research Grant (E-000001-20001; AK) and the Yale Downs Fellowship (ARB). OraSure Technologies, Inc. provided discounted rapid HIV tests. Funders had no role in study design; in the collection, analysis and interpretation of data; in the
Conflict of interest
All authors declare that they do not have any conflict of interests.
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