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Modeling the contribution of incarceration to HIV incidence among people who inject drugs in Tijuana, Mexico Annick Bórquez, Natasha K Martin, Daniela Abramovitz, Steffanie A Strathdee Division of Global Public Health, University of California San Diego In collaboration with: Leo Beletsky, Peter Vickerman, Patricia González-Zúñiga, Gudelia Rangel, Matthew Hickman #AIDS2016 | @AIDS_conference Drug law reform: Mexico • Amendments to Single Convention on Narcotic Drugs being implemented by countries as criminalization has not reduced burden1,2. • “Ley de Narcomenudeo” depenalizes possession of a selection of drugs for personal consumption3,4. To be enforced from 2012 but so far, no substantial changes observed3,4 • Limited enforcement could generate a misleading message regarding the effectiveness of reform Crucial to produce scientific evidence of its missed impact 1. Moore L. and Elkavich A. Who’s using and who’s doing time. Incarceration, the war on drugs and public health. American Journal of Public Health, May 2008, Vol 98, No. 5 2. Beyrer C, et al. Prisoners, prisons, and HIV: time for reform. The Lancet, July 14 2016 3. 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. 4. Werb D. et al. Mexico’s drug policy reform: cutting edge success or crisis in the making? International Journalof Drug Policy 2014;. #AIDS2016 | @AIDS_conference Tijuana case study • Major transit route where drugs trafficked into US • Among PWID, HIV prevalence is 3.5%, HIV incidence is 1% • “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 #AIDS2016 | @AIDS_conference Aims • Describe incarceration patterns and associated behaviors among PWID in Tijuana, Mexico • Use mathematical modeling to: – Estimate contribution of incarceration to the HIV epidemic among PWID since start of drug reform to date (2012-2016) – Estimate potential impact of stopping incarceration or HIV transmission in prison on cumulative incidence among PWID from 2012 to 2016 #AIDS2016 | @AIDS_conference Methods • Descriptive statistics of incarceration patterns and binary logistic regression for HIV associated behaviors using data at baseline (2011-2012) • Dynamic, deterministic compartmental model of HIV transmission among PWID – Injecting and sexual transmission – Disaggregated by sex, incarceration status, and HIV stage – Parameterized with data from the statistical analyses and other epidemiological data in Tijuana #AIDS2016 | @AIDS_conference Incarceration patterns and HIV infection among PWID in Tijuana – 85% and 59% of male and female PWID have ever been incarcerated – Mean number of 5 (SD: 4.6) and 3 (SD: 2.7) incarcerations since starting injecting for male and female PWID, respectively 1 Proportion ever incarcerated 0.8 0.6 0.4 0.2 0 0 10 20 30 40 Injecting duration – Relative risk of HIV infection among ever incarcerated compared to never incarcerated is 1.1 among males and 3.2 among females #AIDS2016 | @AIDS_conference Effect of incarceration on HIV associated risk behaviors Incarceration Any receptive needle sharing Needle sharing at least half the time Never using condoms w/ casual partner Recent vs. None Not recent vs. None Recent vs. None Not recent vs. None Recent vs. None Not recent vs. None Females Males Odds Odds 95%CI 95%CI Ratio Ratio 6.4 0.8 -50.7 5.1 1.1 -24.3 1.6 0.9 -2.7 1.4 0.8 -2.4 5.7 1.6 -19.6 0.7 0.2 -2.1 1.8 1.1 -3.0 0.8 0.5 -1.4 0.7 0.1 -7.2 3.1 0.5 -17.2 2.2 1.1 -4.6 0.6 0.3 -1.3 Outputs used to inform relative risk of infection among those incarcerated in model #AIDS2016 | @AIDS_conference Model parameterization and calibration • Varied parameters associated with demography, incarceration patterns and HIV transmission, including RR of infection by incarceration stage • Fitted to data on HIV prevalence and incidence using Latin Hypercube Sampling • 50,000 parameter sets and resampled runs with Log-likelihood>99th percentile #AIDS2016 | @AIDS_conference Number of new HIV infections Analysis: PAF of incarceration to HIV incidence RR HIV RR HIV #AIDS2016 | @AIDS_conference Baseline 2012 2016 Results: PAF of incarceration among PWID in Tijuana 2012-2016 PAF of incarceration to HIV incidence 45% IQR 95% CrI 35% 25% 15% 5% -5% Full effect Risk at release Long term risk #AIDS2016 | @AIDS_conference Female Male Potential intervention impact: 20122016 Proportion of new HIV infections averted 25% IQR 95% CrI 20% 15% 10% 5% 0% Stop incarceration -5% #AIDS2016 | @AIDS_conference Stop transmission in prison Conclusions • Incarceration contributes substantially to HIV incidence among PWID in Tijuana (PAF=25%), mostly due to longterm impact on risk. Missed opportunity of drug reform to prevent infections • Incarceration of female PWID contributes disproportionately to incidence considering small population size and lower incarceration rates Need focus on this particularly stigmatized population • While elimination of incarceration would have a small impact in the short term, stopping transmission in prison would be an efficient way to reduce incidence Need scale-up of harm reduction interventions in prison #AIDS2016 | @AIDS_conference Limitations and future work • Self reported behaviors • Interpretation of OR for the association of incarceration with risk behaviors • Model’s capacity to reproduce epidemic dynamics Future work should examine: – the potential impact and feasibility of implementing HIV interventions in Tijuana prisons – Cost-effectiveness of the reform enforcement #AIDS2016 | @AIDS_conference Acknowledgments Kenya Lazos Patty Gonzáles Zúñiga Claudia Rafful Mario Morales All the participants of El Cuete study Funding: -UC-MEXUS CONACyT postdoctoral fellowship -UC San Diego Center for AIDS Research (NIAID P30 AI36214) -NIDA U.S.-Mexico drug abuse prevention research fellowship -NIDA grant R01 DA0 19829 -NIDA grant R01 DA037773-01A1 -UCSD CFAR grant P30 AI036214 Pictures from “Tomorrow is a long time: Tijuana’s unchecked #AIDS2016 | @AIDS_conference HIV/AIDS epidemic” by John Cohen and Malcom Linton Tijuana Wound Clinic SEP and basic medical assistance to PWID • Fundraising: https://www.generosity.com/medicalfundraising/Tijuana-wound-clinic-fundraiser Video: https://youtu.be/yUpsL_pJkU4 #AIDS2016 | @AIDS_conference #AIDS2016 | @AIDS_conference Model: HIV transmission • Dynamic HIV transmission through receptive needle sharing • Proportionate mixing • Simplified HIV-Syphilis coinfection model used to estimate contribution of sexual transmission: 2575% Susceptible Acute infection Latent infection Pre-AIDS ART AIDS #AIDS2016 | @AIDS_conference PAF of incarceration 2012-2030 70% 60% 50% 40% 30% 20% 10% 0% -10% Full effect -20% #AIDS2016 | @AIDS_conference Risk at release Long term risk Potential intervention impact 20122030 35% 30% 25% 20% 15% 10% 5% 0% Stop incarceration #AIDS2016 | @AIDS_conference Stop tranmission in prison