Faculty Bibliography

Discussions of drug policy tend not to consider whether the stated goals of policies are an accurate statement of what they are meant to do and also may not consider the fact that what benefits some people may harm others. We explore these issues and present an agenda for research in this area that, while not eliminating these difficulties, both illuminates them and can help guide actors toward more effective action.

Many long-term injection drug users (IDUs) engage in planning strategies. In this pilot study, we examine the relation of one planning strategy to IDUs' engaging in safer injection practices. Sixty-eight IDUs were recruited in 2010 from a New York City (NYC) needle exchange program and referrals to participate in an innovative Staying Safe Intervention that teaches strategies to stay HIV/HCV uninfected. Responses to a baseline 185-item survey were analyzed using correlations and odds ratios. Planning ahead to have steady access to clean equipment was correlated with both individually based and networks-based safety behaviors including storing clean needles; avoiding sharing needles, cookers, and filters with other injectors; and providing clean needles to sex partners. Implications related to resilience in IDUs are discussed and the study's limitations have been noted.

BACKGROUND:HIV transmission among injecting and non-injecting drug users (IDU, NIDU) is a significant public health problem. Continuing propagation in endemic settings and emerging regional outbreaks have indicated the need for comprehensive and coordinated HIV prevention. We describe the development of a conceptual framework and calibration of an agent-based model (ABM) to examine how combinations of interventions may reduce and potentially eliminate HIV transmission among drug-using populations. METHODOLOGY/PRINCIPAL FINDINGS/RESULTS:A multidisciplinary team of researchers from epidemiology, sociology, geography, and mathematics developed a conceptual framework based on prior ethnographic and epidemiologic research. An ABM was constructed and calibrated through an iterative design and verification process. In the model, "agents" represent IDU, NIDU, and non-drug users who interact with each other and within risk networks, engaging in sexual and, for IDUs, injection-related risk behavior over time. Agents also interact with simulated HIV prevention interventions (e.g., syringe exchange programs, substance abuse treatment, HIV testing) and initiate antiretroviral treatment (ART) in a stochastic manner. The model was constructed to represent the New York metropolitan statistical area (MSA) population, and calibrated by comparing output trajectories for various outcomes (e.g., IDU/NIDU prevalence, HIV prevalence and incidence) against previously validated MSA-level data. The model closely approximated HIV trajectories in IDU and NIDU observed in New York City between 1992 and 2002, including a linear decrease in HIV prevalence among IDUs. Exploratory results are consistent with empirical studies demonstrating that the effectiveness of a combination of interventions, including syringe exchange expansion and ART provision, dramatically reduced HIV prevalence among IDUs during this time period. CONCLUSIONS/SIGNIFICANCE/CONCLUSIONS:Complex systems models of adaptive HIV transmission dynamics can be used to identify potential collective benefits of hypothetical combination prevention interventions. Future work will seek to inform novel strategies that may lead to more effective and equitable HIV prevention strategies for drug-using populations.