Modeling the impact of the Mexican drug law reform on HIV incidence among people who inject drugs (PWID) in Tijuana, Mexico. Add other affiliations for Leo and Natasha Annick Bórquez, Leo Beletsky, Daniela Abramovitz, Steffanie A. Strathdee, Claudia Rafful, Peter Vickerman, MC Boily, Natasha K Martin Division of Global Public Health, UCSD Lisbon Addictions, 10/24/2017

Conflict of interest None to declare

Drug law reform: Mexico “Reforma de Narcomenudeo” depenalizes possession of a selection of drugs for personal consumption1,2 => decrease incarceration rates and police harassment and mandates drug treatment at 3rd apprehension => increase treatment rates To be enforced from 2012 but so far, no substantial changes observed.1,2 Limited enforcement could generate a misleading message regarding the effectiveness of reform Crucial to produce scientific evidence of its potential impact 1. Mackey TK et al. Mexico's "ley de narcomenudeo" drug policy reform and the international drug control regime. Harm reduction journal 2014; 11(1): 31. 2. Werb D. et al. Mexico’s drug policy reform: cutting edge success or crisis in the making? International Journal of Drug Policy 2014;. Availability of concrete outcomes can serve as a motivation to policy makers and promote accountability. Size of prison population over time in mexico and proportion incarcerated due to drug offences

Tijuana, as case study Major transit route where drugs trafficked into US Large PWID population (5,000- 10,000) Among PWID, HIV prevalence is 3.5%, HIV incidence is 1-2%/year “Proyecto El Cuete IV”: cohort study following 734 PWID in Tijuana bi- annually from 2011-2020 HIV test self-reports of sexual and drug- using behaviors, policing, incarceration, and access to harm reduction following 734 PWID in Tijuana bi-annually from 2011-2020 HIV test self-reports of sexual and drug-using behaviors, policing, incarceration, and access to harm reduction

Exposures among PWID in Tijuana Incarceration 85% and 59% of male and female PWID have ever been incarcerated 5 (SD: 4.6) and 3 (SD: 2.7) times on average since starting injecting, respectively 80% of incarcerations approx. associated with drug use => No changes observed since 2011 Syringe confiscation by the police in past 6 months 11% reported having syringes confiscated by the police at baseline => Declined to 0% from 2011 to 2015 Drug treatment Non evidence-based treatment (religious, 12 steps, mutual help) Very limited access to opioid agonist therapy (OAT)

Aims Use mathematical modeling to: 1) Estimate the contribution of incarceration and police harassment to the HIV epidemic among PWID assuming no drug law reform from 2012-2030; 2) Predict the potential impact of the Narcomenudeo reform under different enforcement scenarios from 2018-2030.

Methods Log-binomial regression to measure the relative risk of receptive syringe sharing associated with exposures of interest, controlling for duration of injection, using data at baseline (2011-2012) Dynamic, deterministic compartmental model of HIV transmission among PWID Injecting and sexual transmission Varied parameters associated with demography, incarceration/syringe confiscation patterns and HIV transmission Fitted to data on HIV prevalence and incidence using Latin Hypercube Sampling and resampled best fitting simulations Disaggregated by sex, incarceration stage, syringe confiscation exposure, drug treatment and HIV stage

Model diagram On OAT or *In prison, no syringe confiscation by the police occurs as there is no interaction with the police. In the red square, involuntary treatment or opiate agonist therapy (OAT) instead of incarceration as alternative scenarios of the drug law reform implementation

Any receptive needle sharing Relative risk of receptive syringe sharing by type of exposure among PWID in Tijuana Any receptive needle sharing Past 6 months Relative risk 95%CI p-value Incarceration Recent vs. None 1.40 1.21 1.63 <0.0001 Not recent vs. None 1.11 0.99 1.26 0.07 Syringe confiscation Recent vs. Not 1.16 1.03 1.29 0.01 Involuntary treatment Ever vs. Never 1.14 1.00 1.30 0.04

Modeling Analysis: Never incarcerated Prison 2012 2030 Baseline Never incarcerated Prison Recently incarcerated (< 6 months ago) Previously Incarcerated (> 6months ago) Number of new HIV infections Reproduce observed trends Simplified cohort model used to estimate: -Proportion ever incarcerated when starting injecting -Primary incarceration rate RR HIV RR HIV

Contribution of incarceration and syringe confiscation to HIV incidence among PWID 2012-2030 Mean: 25.3% Mean: 22.8% Mean: 16.1% Mean: 7.9% Mean: 4.3% Between 2012 and 2017, observed decline in syringe confiscation by the police resulted in a 2% (95% CrI: 0.3%-3%)reduction in the number of new HIV infections

Proportion of new infections averted 2018-2030 under different Narcomenudeo reform enforcement scenarios

Conclusions Incarceration contributes substantially to HIV incidence among PWID in Tijuana (PAF=23% between 2012-2030).  Missed opportunity of drug law reform to prevent infections Reducing syringe confiscation and incarceration rates among PWID would have an impact on the epidemic  Not sufficient to curb it Involuntary treatment in non-evidence based centers would potentially increase HIV incidence among PWID  If improperly implemented this public health oriented reform could have negative health consequences for PWID Referral to evidence based drug treatment as mandated in the Narcomenudeo reform would potentiate the epidemic decline (20% reduction in incidence) among other positive outcomes.  Need to scale up of OAT services in Tijuana

Acknowledgments Thank you! Funding: -NIDA U.S.-Mexico drug abuse prevention research fellowship -UC-MEXUS CONACyT postdoctoral fellowship -UC San Diego Center for AIDS Research (NIAID P30 AI36214) -NIDA grant R01 DA0 19829 -NIDA grant R01 DA037773-01A1 Patty González Zúñiga Kenya Lazos All the participants of El Cuete study Thank you! Pictures from “Tomorrow is a long time: Tijuana’s unchecked HIV/AIDS epidemic” by John Cohen and Malcom Linton

Extra slides

Limitations and future work Self reported behaviors Need to establish causality Model’s capacity to reproduce epidemic dynamics Future work should examine: Cost-effectiveness Bayesian sensitivity

Model fitting: