Evaluating the impact of Mexico's drug policy reforms on people who inject drugs in Tijuana, B.C., Mexico, and San Diego, CA, United States: a binational mixed methods research agenda

Long-acting Injectable PrEP Interest and General PrEP Awareness among People who Inject Drugs in the San Diego-Tijuana Border Metroplex

Long-acting injectable HIV pre-exposure prophylaxis (LAI-PrEP) could help overcome multilevel challenges to HIV prevention for people who inject drugs (PWID), including those in the binational San Diego-Tijuana metroplex. Yet, general PrEP awareness and interest in LAI-PrEP remain underexplored among PWID. From 2020 to 2021, 562 HIV-negative PWID in San Diego and Tijuana completed surveys assessing general PrEP awareness and interest in oral and LAI-PrEP. Modified Poisson regression examined factors associated with general PrEP awareness. Multinomial logistic regression assessed factors associated with interest in both oral and LAI-PrEP, oral PrEP only, LAI-PrEP only, or neither. General PrEP awareness was low (18%) and associated with experiencing unsheltered homelessness (adjusted prevalence ratio [APR] = 1.50, 95% confidence interval [CI]: 0.96-2.33), past 6-month fentanyl injection (APR = 1.53, 95% CI: 1.04-2.25), and transactional sex (APR = 1.71, 95% CI: 1.06-2.76). Interest in oral PrEP only was most common (44%), followed by LAI-PrEP only (25%) and neither (16%). Compared to the odds of being interested in LAI-PrEP only, the odds of being interested in oral PrEP only were lower among those who were stopped by police (AOR = 0.38, 95% CI: 0.22-0.65), reported past 6-month fentanyl injection (AOR = 0.33, 95% CI: 0.20-0.56), polydrug use (AOR = 0.48, 95% CI: 0.27-0.86), injecting multiple times daily (AOR = 0.26, 95% CI: 0.14-0.46), receptive syringe use (AOR = 0.30, 95% CI: 0.19-0.49), and higher perceived HIV risk (AOR = 0.24, 95% CI: 0.15-0.39). Interest in LAI-PrEP was more common among PWID reporting social and structural factors that could interfere with oral PrEP adherence, suggesting LAI-PrEP implementation could increase PrEP coverage among those most vulnerable to HIV.

Cost-effectiveness of a police education program on HIV and overdose among people who inject drugs in Tijuana, Mexico

Background

Incarceration is associated with drug-related harms among people who inject drugs (PWID). We trained >1800 police officers in Tijuana, Mexico on occupational safety and HIV/HCV, harm reduction, and decriminalization reforms (Proyecto Escudo). We evaluated its effect on incarceration, population impact and cost-effectiveness on HIV and fatal overdose among PWID.

Methods

We assessed self-reported recent incarceration in a longitudinal cohort of PWID before and after Escudo. Segmented regression was used to compare linear trends in log risk of incarceration among PWID pre-Escudo (2012-2015) and post-Escudo (2016-2018). We estimated population impact using a dynamic model of HIV transmission and fatal overdose among PWID, with incarceration associated with syringe sharing and fatal overdose. The model was calibrated to HIV and incarceration patterns in Tijuana. We compared a scenario with Escudo (observed incarceration declines for 2 years post-Escudo among PWID from the segmented regression) compared to a counterfactual of no Escudo (continuation of stable pre-Escudo trends), assessing cost-effectiveness from a societal perspective. Using a 2-year intervention effect and 50-year time horizon, we determined the incremental cost-effectiveness ratio (ICER, in 2022 USD per disability-adjusted life years [DALYs] averted).

Findings

Compared to stable incarceration pre-Escudo, for every three-month interval in the post-Escudo period, recent incarceration among PWID declined by 21% (adjusted relative risk = 0.79, 95% CI: 0.68-0.91). Based on these declines, we estimated 1.7% [95% interval: 0.7%-3.5%] of new HIV cases and 12.2% [4.5%-26.6%] of fatal overdoses among PWID were averted in the 2 years post-Escudo, compared to a counterfactual without Escudo. Escudo was cost-effective (ICER USD 3746/DALY averted compared to a willingness-to-pay threshold of $4842-$13,557).

Interpretation

Escudo is a cost-effective structural intervention that aligned policing practices and human-rights-based public health practices, which could serve as a model for other settings where policing constitutes structural HIV and overdose risk among PWID.

Funding

National Institute on Drug Abuse, UC MEXUS CONACyT, and the San Diego Center for AIDS Research (SD CFAR).

Modelling the contribution of incarceration and public health oriented drug law reform to HCV transmission and elimination among PWID in Tijuana, Mexico

BACKGROUND

Incarceration is associated with increased risk of hepatitis C virus (HCV) among people who inject drugs (PWID). Mexico's previous attempt in implementing a public health-oriented drug law reform resulted in minimal impact on incarceration among PWID. However, implementation of reforms alongside Mexico's HCV elimination program has the potential to reshape the HCV epidemic among PWID in the next decade. We use data from a cohort of PWID in Tijuana, Mexico, to inform epidemic modeling to assess the contribution of incarceration and fully implemented drug reform on HCV transmission and elimination among PWID.

METHODS

We developed a dynamic, deterministic model of incarceration, HCV transmission and disease progression among PWID. The model was calibrated to data from Tijuana, Mexico, with 90% HCV seroprevalence among 10,000 PWID. We estimated the 10-year population attributable fraction (PAF) of incarceration to HCV incidence among PWID and simulated, from 2022, the potential impact of the following scenarios: 1) decriminalization (80% reduction in incarceration rates); 2) fully implemented drug law reform (decriminalization and diversion to opiate agonist therapy [OAT]); 3) fully implemented drug law reform with HCV treatment (direct-acting antivirals [DAA]). We also assessed the number DAA needed to reach the 80% incidence reduction target by 2030 under these scenarios.

RESULTS

Projections suggest a PAF of incarceration to HCV incidence of 5.4% (95% uncertainty interval [UI]:0.6-11.9%) among PWID in Tijuana between 2022-2032. Fully implemented drug reforms could reduce HCV incidence rate by 10.6% (95%UI:3.1-19.2%) across 10 years and reduce the number of DAA required to achieve Mexico's HCV incidence reduction goal by 14.3% (95%UI:5.3-17.1%).

CONCLUSIONS

Among PWID in Tijuana, Mexico, incarceration remains an important contributor to HCV transmission. Full implementation of public health-oriented drug law reform could play an important role in reducing HCV incidence and improve the feasibility of reaching the HCV incidence elimination target by 2030.

Typologies and Correlates of Police Violence Against Female Sex Workers Who Inject Drugs at the México-United States Border: Limits of De Jure Decriminalization in Advancing Health and Human Rights

Decriminalization of sex work is increasingly promoted as a structural measure to improve the health of vulnerable groups. In México, sex work is not illegal, but knowledge of policies' street-level impact is limited. This study describes typologies of police violence against female sex workers who inject drugs (FSWID), identifying risk and protective factors for violence exposure to inform policy responses. Survey data were collected during 2008-2010 among HIV-negative FSWID in a behavioral intervention in Tijuana and Ciudad Juarez (N = 584). Latent class analysis identified typologies of police violence in the past 6 months: asked for money, money taken, syringes taken, asked for sex, and sexually assaulted. Structural equation modeling (SEM) predicted latent class membership using sociodemographic, behavioral and risk environment factors, controlling for age, education, marital status, and city. Recent police violence was reported by 68% of FSWID, with three typologies emerging: Low (36.6%); Material (47.8%): having money/syringes taken or being asked for money; and Material/Sexual (15.7%): material violence and being asked for sex or sexually assaulted. In multivariable SEM, Material Violence was associated with: being jailed [adjusted Odds Ratio (aOR) = 4.34], HIV testing (aOR = 2.18), and trading sex indoors (aOR = 1.66). Factors associated with Material/Sexual Violence included: being jailed (aOR = 41.18), injecting with clients (aOR = 3.12), earning more money for sex without a condom (aOR = 2.88), being raped by a client (aOR = 2.13), drinking with clients (aOR = 2.03), receiving substance use treatment (aOR = 1.95), being <18 when first trading sex (aOR = .43), trading sex outdoors (aOR = .53), and poor working conditions (aOR = .56). Despite de jure decriminalization of sex work, police violence against FSWID at the México-United States border is pervasive with implications for sex- and drug-related harms. Closing gaps in policy implementation and mitigating material/sexual violence from police is imperative to decreasing economic vulnerability, risk of overdose and HIV, and improving engagement in HIV and harm reduction services.

Gender and the first-time provision of injection initiation assistance among people who inject drugs across two distinct North American contexts: Tijuana, Mexico and Vancouver, Canada

INTRODUCTION

Injection drug use initiation is commonly facilitated by other people who inject drugs (PWID). We investigated how the gender of PWID influences their risk of providing initiation assistance to others across two distinct geo-cultural settings.

METHODS

Data were drawn from two prospective cohorts in Tijuana, Mexico and Vancouver, Canada which conducted semi-annual interviews within the PReventing Injecting by Modifying Existing Responses (PRIMER) study. Participants consisted of PWID who had reported never providing injection initiation assistance at baseline. We then conducted site-specific discrete-time survival analyses assessing the relationship between gender and other relevant covariates (e.g. age and past 6-month sex work) on the risk of the first reported instance of providing initiation assistance.

RESULTS

Of 1988 PWID (Tijuana: n = 596; Vancouver: n = 1392), 256 (43%) and 511 (36.7%) participants were women, and 42 (1.7%) and 78 (1.6%) reported recent injection initiation assistance across a median of three and two follow-up visits, respectively. Women had a lower risk of providing injection initiation assistance for the first time in Tijuana (adjusted hazard ratio = 0.52, 95% confidence interval 0.27-0.99), but not in Vancouver. Gendered pathways, like sex work, were associated with providing initiation assistance for the first time in Vancouver (adjusted hazard ratio = 1.97, 95% confidence interval 1.08-3.61).

DISCUSSION AND CONCLUSIONS

Women in Tijuana, but not Vancouver, were less likely to provide first-time initiation assistance among PWID. These results can inform gender- and site-specific prevention efforts aimed at reducing transitions into drug injecting across geographic contexts.

Prevalence and correlates of SARS-CoV-2 seropositivity among people who inject drugs in the San Diego-Tijuana border region

BACKGROUND

People who inject drugs may be at elevated SARS-CoV-2 risk due to their living conditions and/or exposures when seeking or using drugs. No study to date has reported upon risk factors for SARS-CoV-2 infection among people who inject drugs.

METHODS AND FINDINGS

Between October, 2020 and June, 2021, participants aged ≥18 years from San Diego, California, USA and Tijuana, Baja California, Mexico who injected drugs within the last month underwent interviews and testing for SARS-CoV-2 RNA and antibodies. Binomial regressions identified correlates of SARS-CoV-2 seropositivity.

RESULTS

Of 386 participants, SARS-CoV-2 seroprevalence was 36.3% (95% CI: 31.5%-41.1%); 92.1% had detectable IgM antibodies. Only 37.5% had previously been tested. Seroprevalence did not differ by country of residence. None tested RNA-positive. Most (89.5%) reported engaging in ≥1 protective behavior [e.g., facemasks (73.5%), social distancing (46.5%), or increasing handwashing/sanitizers (22.8%)]. In a multivariate model controlling for sex, older age, and Hispanic/Latinx/Mexican ethnicity were independently associated with SARS-CoV-2 seropositivity, as was engaging in sex work (AdjRR: 1.63; 95% CI: 1.18-2.27) and having been incarcerated in the past six months (AdjRR: 1.49; 95% CI: 0.97-2.27). Comorbidities and substance using behaviors were not associated with SARS-CoV-2 seropositivity.

CONCLUSIONS

In this community-based study of people who inject drugs in the San Diego-Tijuana border region, over one third were SARS-CoV-2 seropositive, exceeding estimates from the general population in either city. We found no evidence that substance use behaviors were associated with an elevated risk of SARS-CoV-2 infection, but observed that circumstances in the risk environment, notably sex work and incarceration, were independently associated with higher SARS-CoV-2 seroprevalence. Our findings suggest that a binational policy response to COVID-19 mitigation is warranted beyond the closure of the U.S.-Mexico border. Furthermore, decriminalizing sex work and drug use could reduce the burden of COVID-19 among people who inject drugs.

Overlapping Key Populations and HIV Transmission in Tijuana, Mexico: A Modelling Analysis of Epidemic Drivers

Tijuana, Mexico, has a concentrated HIV epidemic among overlapping key populations (KPs) including people who inject drugs (PWID), female sex workers (FSW), their male clients, and men who have sex with men (MSM). We developed a dynamic HIV transmission model among these KPs to determine the extent to which their unmet prevention and treatment needs is driving HIV transmission. Over 2020-2029 we estimated the proportion of new infections acquired in each KP, and the proportion due to their unprotected risk behaviours. We estimate that 43.7% and 55.3% of new infections are among MSM and PWID, respectively, with FSW and their clients making-up < 10% of new infections. Projections suggest 93.8% of new infections over 2020-2029 will be due to unprotected sex between MSM or unsafe injecting drug use. Prioritizing interventions addressing sexual and injecting risks among MSM and PWID are critical to controlling HIV in Tijuana.

"I would rather do it myself": injection initiation and current injection patterns among women who inject drugs in Tijuana, Mexico

BACKGROUND

Women who inject drugs (WWID) experience unique risks and adverse health outcomes related to injection initiation and patterns of injection drug use. However, there is limited information on injection initiation experiences and injection patterns among women and the protective strategies employed to limit injection-related harms, especially in low- and middle-income settings. Therefore, this study sought to explore injection initiation and current injection patterns (e.g., relying on someone else to inject) among women who inject drugs and engage in sex work in Tijuana, Mexico.

METHODS

Semistructured in-depth interviews were conducted with 30 WWID on the following topics: injection initiation, current injection patterns, places where women inject, and protective strategies (i.e., risk reduction). All interviews were audio-recorded, transcribed, and de-identified. An inductive thematic analysis was conducted to identify and compare common themes and patterns across participants.

RESULTS

The interviews revealed that the vast majority of study participants were first initiated by another person who injects drugs (PWID), often a male sexual partner. However, the majority of the women transitioned to become self-injectors in order to avoid risks associated with relying on others for injection, including overdose, interpersonal violence, sexual abuse, and wounds. Those who relied on others indicated that they would prefer to inject themselves without assistance from others if they were able to.

CONCLUSIONS

The narratives uncovered in this study reveal the importance of multiple risk environments in shaping perceived risks associated with injection drug use among women in Tijuana, Mexico. Specifically, the interviews elucidate the connection between interpersonal relationships with other PWID and protective strategies used to minimize risk and harm. These findings highlight the need for women-centered harm reduction programs to facilitate the development of safer drug use environments among WWID in Tijuana, Mexico.

Impact of cumulative incarceration and the post-release period on syringe-sharing among people who inject drugs in Tijuana, Mexico: a longitudinal analysis

BACKGROUND AND AIMS

Syringe-sharing among people who inject drugs, which can occur during incarceration and post-release, has been linked with increased risk of blood-borne infections. We aimed to investigate the cumulative effect of repeated incarceration and the post-release period on receptive syringe-sharing.

DESIGN

Ongoing community-based cohort, recruited through targeted sampling between 2011 and 2012 with 6-month follow-ups.

SETTING

Tijuana, Mexico.

PARTICIPANTS

Sample of 185 participants (median age 35 years; 67% female) with no history of incarceration at study entry, followed to 2017.

MEASUREMENTS

Cumulative incarceration and post-release period were constructed from incarceration events reported in the past 6 months for each study visit. Receptive syringe-sharing in the past 6 months was assessed as a binary variable. We used logistic regression with generalized estimating equations to examine the association between cumulative incarceration events and the post-release period with receptive syringe-sharing over time. Missing data were handled through multiple imputation.

FINDINGS

At baseline, 65% of participants engaged in receptive syringe-sharing in the prior 6 months. At follow-up, 150 (81%) participants experienced a total of 358 incarceration events [median = 2, interquartile range (IQR) = 1-3]. The risk of receptive syringe-sharing increased with the number of repeated incarcerations. Compared with never incarcerated, those with one incarceration had 1.28 [95% confidence interval (CI) = 0.97-1.68] higher adjusted odds of syringe-sharing; two to three incarcerations, 1.42 (95% CI = 1.02-1.99) and more than three incarcerations, 2.10 (95% CI = 1.15-3.85). Participants released within the past 6 months had 1.53 (95% CI = 1.14-2.05) higher odds of sharing syringes compared with those never incarcerated. This post-release risk continued up to 1.5 years post-incarceration (adjusted odds ratio = 1.41, 95% CI = 1.04-1.91), but then waned.

CONCLUSIONS

A longitudinal community cohort study among people who inject drugs suggested that the effects of incarceration on increased injecting risk, measured through syringe-sharing, are cumulative and persist during the post-release period.

Cost-effectiveness of hepatitis C virus (HCV) elimination strategies among people who inject drugs (PWID) in Tijuana, Mexico

BACKGROUND AND AIMS

In Latin America, Mexico was first to launch a hepatitis C virus (HCV) elimination strategy, where people who inject drugs (PWID) are a main risk group for transmission. In Tijuana, HCV seroprevalence among PWID is > 90%, with minimal harm reduction (HR). We evaluated cost-effectiveness of strategies to achieve the incidence elimination target among PWID in Tijuana.

METHODS

Modeling study using a dynamic, cost-effectiveness model of HCV transmission and progression among active and former PWID in Tijuana, to assess the cost-effectiveness of incidence elimination strategies from a health-care provider perspective. The model incorporated PWID transitions between HR stages (no HR, only opioid agonist therapy, only high coverage needle-syringe programs, both). Four strategies that could achieve the incidence target (80% reduction by 2030) were compared with the status quo (no intervention). The strategies incorporated the number of direct-acting anti-viral (DAA) treatments required with: (1) no HR scale-up, (2) HR scale-up from 2019 to 20% coverage among PWID, (3) HR to 40% coverage and (4) HR to 50% coverage. Costs (2019 US$) and health outcomes [disability-adjusted life years (DALYs)] were discounted 3% per year. Mean incremental cost-effectiveness ratios (ICER, $/DALY averted) were compared with one-time per capita gross domestic product (GDP) ($9698 in 2019) and purchasing power parity-adjusted per capita GDP ($4842-13 557) willingness-to-pay (WTP) thresholds.

RESULTS

DAAs alone were the least costly elimination strategy [$173 million, 95% confidence interval (CI) = 126-238 million], but accrued fewer health benefits compared with strategies with HR. DAAs + 50% HR coverage among PWID averted the most DALYs but cost $265 million, 95% CI = 210-335 million). The optimal strategy was DAAs + 50% HR (ICER $6743/DALY averted compared to DAAs only) under the one-time per-capita GDP WTP ($9698).

CONCLUSIONS

A combination of high-coverage harm reduction and hepatitis C virus treatment is the optimal cost-effective strategy to achieve the HCV incidence elimination goal in Mexico.

Involvement of people who inject drugs in injection initiation events: a cross-sectional analysis identifying similarities and differences across three North American settings

OBJECTIVES

People who inject drugs (PWID) play an integral role in facilitating the entry of others into injection drug use (IDU). We sought to assess factors influencing PWID in providing IDU initiation assistance across three distinct North American settings and to generate pooled measures of risk.

DESIGN

We employed data from three PWID cohort studies participating in PReventing Injecting by Modifying Existing Responses (PRIMER), for this cross-sectional analysis.

SETTING

Tijuana, Mexico; San Diego, USA; Vancouver, Canada.

PARTICIPANTS

A total of 2944 participants were included in this study (Tijuana: n=766, San Diego: n=353, Vancouver: n=1825).

MEASUREMENTS

The outcome was defined as recently (ie, past 6 months) assisting in an IDU initiation event. Independent variables of interest were identified from previous PRIMER analyses. Site-specific multiple modified Poisson regressions were fit. Pooled relative risks (pRR) were calculated and heterogeneity across sites was assessed via linear random effects models.

RESULTS

Evidence across all three sites indicated that having a history of providing IDU initiation assistance (pRR: 4.83, 95% CI: 3.49 to 6.66) and recently being stopped by law enforcement (pRR: 1.49, 95% CI: 1.07 to 2.07) were associated with a higher risk of providing assistance with IDU initiation; while recent opioid agonist treatment (OAT) enrolment (pRR: 0.64, 95% CI: 0.43 to 0.96) and no recent IDU (pRR: 0.21, 95% CI: 0.07 to 0.64) were associated with a lower risk. We identified substantial differences across site in the association of age (I²: 52%), recent housing insecurity (I²: 39%) and recent non-injection heroin use (I²: 78%).

CONCLUSION

We identified common and site-specific factors related to PWID's risk of assisting in IDU initiation events. Individuals reporting a history of assisting IDU initiations, being recently stopped by law enforcement, and recently injecting methamphetamine/speedball were more likely to have recently assisted an IDU initiation. Whereas those who reported not recently engaging in IDU and those recently enrolled in OAT were less likely to have done so. Interventions and harm reduction strategies aimed at reducing the harms of IDU should incorporate context-specific approaches to reduce the initiation of IDU.

Investigating a bidirectional relationship between overdose and provision of injection initiation assistance among persons who inject drugs in Vancouver, Canada and Tijuana, Mexico

BACKGROUND

Individuals who initiate injection drug use often receive assistance from an injection-knowledgeable peer. Persons who assist peers in injection initiation events often inject frequently, which heightens overdose risk. As such, overdose and injection initiation events may be correlated. To explore a potential relationship, we assessed temporal associations between experiencing a non-fatal overdose and assisting others in initiating injection drug use among persons who inject drugs in two North American cities - Vancouver, Canada and Tijuana, Mexico.

METHODS

From 2014 to 2018, this retrospective cohort study included people who inject drugs from Vancouver (n=1332) and Tijuana (n=666) who completed a baseline and six-month follow-up interview. Within each site, we assessed bidirectional temporal associations using two separate multivariable logistic regression models: for model 1, recent provision of injection initiation assistance (at six months) was the outcome and recent overdose (at baseline) was the exposure; for model 2, recent overdose (at six months) was the outcome and recent provision of injection initiation assistance (at baseline) was the exposure. Both models adjusted for potential confounders.

RESULTS

Vancouver-based participants reporting overdose at baseline had 163% greater odds of reporting provision of injection initiation assistance at follow-up (adjusted Odds Ratio [aOR] 2.63; 95% Confidence Interval [CI] 1.41-4.90); while participants reporting provision of injection initiation assistance at baseline had 89% greater odds of reporting a non-fatal overdose at follow-up (aOR 1.89; 95% CI 1.00-3.57). Among Tijuana-based participants, we did not observe a statistically significant association in either direction.

CONCLUSION

Findings in Vancouver suggest that injection initiation assistance and overdose are bidirectionally-associated phenomena. The present findings highlight the need for interventions that ensure that persons who provide injection initiation assistance are given overdose prevention support, both for themselves and for those they assist to initiate injection drug use. While our Tijuana-based results did not suggest a bidirectional relationship, preventative approaches should nonetheless be undertaken.

The impact of recent homelessness on the provision of injection drug use initiation assistance among persons who inject drugs in Tijuana, Mexico and Vancouver, Canada

OBJECTIVE

To assess the relationship between experiencing homelessness and assisting injection drug use (IDU) initiation among people who inject drugs (PWID) in Tijuana, Mexico and Vancouver, Canada.

METHODS

We used self-reported questionnaire data collected semi-annually on PWID from Tijuana (n = 703) and Vancouver (n = 1551) between 2014 and 2017. Within each setting, the effect of recent (i.e., past six months) homelessness on recent provision of injection initiation assistance (i.e., helping anybody inject for the first time in the past six months) was estimated using inverse-probability-of-treatment (IPT)-weighted estimation of a marginal structural model.

RESULTS

Across follow-up, the prevalence of recent homelessness at a given visit ranged from 11.6%-16.5% among Tijuana-based participants and 9.4%-18.9% among Vancouver-based participants; the prevalence of recent provision of injection initiation at a given follow-up visit was lower, ranging from 3.3%-5.4% in Tijuana and 2.5%-4.1% in Vancouver. Based on the IPT-weighted estimates, recent homelessness was associated with 66% greater odds among Tijuana-based PWID (Adjusted Odds Ratio [AOR] = 1.66; 95% CI: 1.01-2.73) and 47% greater odds among Vancouver-based PWID (AOR = 1.47, 95% CI: 1.02-2.13) of providing injection initiation assistance over the same six-month period.

CONCLUSION

We found that recently experiencing homelessness was associated with an increased likelihood of PWID reporting IDU initiation assistance over time in both Tijuana and Vancouver. Addressing homelessness may decrease the initiation of IDU via multiple pathways.

Municipal police support for harm reduction services in officer-led referrals of people who inject drugs in Tijuana, Mexico

BACKGROUND

Police constitute a structural determinant of health and HIV risk of people who inject drugs (PWID), and negative encounters with law enforcement present significant barriers to PWID access to harm reduction services. Conversely, police may facilitate access via officer-led referrals, potentiating prevention of HIV, overdose, and drug-related harms. We aimed to identify police characteristics associated with support for officer-led referrals to addiction treatment services and syringe service programs (SSP). We hypothesized that officers who believe harm reduction services are contradictory to policing priorities in terms of safety and crime reduction will be less likely to support police referrals.

METHODS

Between January and June 2018, police officers (n = 305) in Tijuana, Mexico, completed self-administered surveys about referrals to harm reduction services during the 24-month follow-up visit as part of the SHIELD police training and longitudinal cohort study. Log-binomial regression was used to estimate adjusted prevalence ratios and model policing characteristics and attitudes related to officers' support for including addiction treatment and SSP in referrals.

RESULTS

Respondents were primarily male (89%), patrol officers (86%) with a median age of 38 years (IQR 33-43). Overall, 89% endorsed referral to addiction services, whereas 53% endorsed SSP as acceptable targets of referrals. Officers endorsing addiction services were less likely to be assigned to high drug use districts (adjusted prevalence ratio [APR] = 0.50, 95% CI 0.24, 1.08) and more likely to agree that methadone programs reduce crime (APR = 4.66, 95% CI 2.05, 9.18) than officers who did not support addiction services. Officers endorsing SSPs were younger (adjusted prevalence ratio [APR] = 0.96 95% CI 0.93, 0.98), less likely to be assigned to high drug use districts (APR = 0.50, 95% CI 0.29, 0.87), more likely to believe that methadone programs reduce crime (APR = 2.43, 95% CI 1.30, 4.55), and less likely to believe that SSPs increase risk of needlestick injury for police (APR = 0.44, 0.27, 0.71).

CONCLUSIONS

Beliefs related to the occupational impact of harm reduction services in terms of officer safety and crime reduction are associated with support for referral to related harm reduction services. Efforts to deflect PWID from carceral systems toward harm reduction by frontline police should include measures to improve officer knowledge and attitudes about harm reduction services as they relate to occupational safety and law enforcement priorities.

TRIAL REGISTRATION

NCT02444403.

Integrating Phylogenetic Biomarker Data and Qualitative Approaches: An example of HIV Transmission Clusters as a Sampling Frame for Semistructured Interviews and Implications for the COVID-19 Era

Mixed methods studies of human disease that combine surveillance, biomarker, and qualitative data can help elucidate what drives epidemiological trends. Viral genetic data are rarely coupled with other types of data due to legal and ethical concerns about patient privacy. We developed a novel approach to integrate phylogenetic and qualitative methods in order to better target HIV prevention efforts. The overall aim of our mixed methods study was to characterize HIV transmission clusters. We combined surveillance data with HIV genomic data to identify cases whose viruses share enough similarities to suggest a recent common source of infection or participation in linked transmission chains. Cases were recruited through a multi-phase process to obtain consent for recruitment to semi-structured interviews. Through linkage of viral genetic sequences with epidemiological data, we identified individuals in large transmission clusters, which then served as a sampling frame for the interviews. In this article, we describe the multi-phase process and the limitations and challenges encountered. Our approach contributes to the mixed methods research field by demonstrating that phylogenetic analysis and surveillance data can be harnessed to generate a sampling frame for subsequent qualitative data collection, using an explanatory sequential design. The process we developed also respected protections of patient confidentiality. The novel method we devised may offer an opportunity to implement a sampling frame that allows for the recruitment and interview of individuals in high-transmission clusters to better understand what contributes to spread of other infectious diseases, including COVID-19.

Risk of non-fatal overdose and polysubstance use in a longitudinal study with people who inject drugs in Tijuana, Mexico

INTRODUCTION

Among people who inject drugs (PWID), polysubstance use has been associated with fatal and non-fatal overdose (NFOD). However, the risk of overdose due to the cumulative number of various recently used drug types remains unexplored. We estimated the risk of NFOD for different polysubstance use categories among PWID in Tijuana, Mexico.

METHODS

Data came from 661 participants followed for 2 years in Proyecto El Cuete-IV, an ongoing prospective cohort of PWID. A multivariable Cox model was used to assess the cumulative impact of polysubstance use on the time to NFOD. We used the Cochran-Armitage test to evaluate a dose-response relationship between number of polysubstance use categories and NFOD.

RESULTS

We observed 115 NFOD among 1029.2 person-years of follow-up (incidence rate: 11.2 per 100 person-years; 95% confidence interval [CI] 9.3-13.3). Relative to those who used one drug class, the adjusted hazard ratio of NFOD for individuals reporting using two drug classes was 1.11 (95% CI 0.69-1.79), three drug classes was 2.00 (95% CI 1.16-3.44) and for those reporting three compared to two was 1.79 (95% CI 1.09-2.97). A significant Cochran-Armitage trend test (P < 0.001) suggested a dose-response relationship.

DISCUSSION AND CONCLUSIONS

Polysubstance use was associated with increased risk of NFOD with a dose-response relationship over 2 years. We identified a subgroup of PWID at high risk of NFOD who reported concurrent use of opioids, stimulants and benzodiazepines. Prioritising tailored harm reduction and overdose prevention interventions for PWID who use multiple substances in Tijuana is needed.

Homelessness, unstable housing, and risk of HIV and hepatitis C virus acquisition among people who inject drugs: a systematic review and meta-analysis

BACKGROUND

People who inject drugs (PWID) are at increased risk for HIV and hepatitis C virus (HCV) infection and also have high levels of homelessness and unstable housing. We assessed whether homelessness or unstable housing is associated with an increased risk of HIV or HCV acquisition among PWID compared with PWID who are not homeless or are stably housed.

METHODS

In this systematic review and meta-analysis, we updated an existing database of HIV and HCV incidence studies published between Jan 1, 2000, and June 13, 2017. Using the same strategy as for this existing database, we searched MEDLINE, Embase, and PsycINFO for studies, including conference abstracts, published between June 13, 2017, and Sept 14, 2020, that estimated HIV or HCV incidence, or both, among community-recruited PWID. We only included studies reporting original results without restrictions to study design or language. We contacted authors of studies that reported HIV or HCV incidence, or both, but did not report on an association with homelessness or unstable housing, to request crude data and, where possible, adjusted effect estimates. We extracted effect estimates and pooled data using random-effects meta-analyses to quantify the associations between recent (current or within the past year) homelessness or unstable housing compared with not recent homelessness or unstable housing, and risk of HIV or HCV acquisition. We assessed risk of bias using the Newcastle-Ottawa Scale and between-study heterogeneity using the I2 statistic and p value for heterogeneity.

FINDINGS

We identified 14 351 references in our database search, of which 392 were subjected to full-text review alongside 277 studies from our existing database. Of these studies, 55 studies met inclusion criteria. We contacted the authors of 227 studies that reported HIV or HCV incidence in PWID but did not report association with the exposure of interest and obtained 48 unpublished estimates from 21 studies. After removal of duplicate data, we included 37 studies with 70 estimates (26 for HIV; 44 for HCV). Studies originated from 16 countries including in North America, Europe, Australia, east Africa, and Asia. Pooling unadjusted estimates, recent homelessness or unstable housing was associated with an increased risk of acquiring HIV (crude relative risk [cRR] 1·55 [95% CI 1·23-1·95; p=0·0002]; I2= 62·7%; n=17) and HCV (1·65 [1·44-1·90; p<0·0001]; I2= 44·8%; n=28]) among PWID compared with those who were not homeless or were stably housed. Associations for both HIV and HCV persisted when pooling adjusted estimates (adjusted relative risk for HIV: 1·39 [95% CI 1·06-1·84; p=0·019]; I2= 65·5%; n=9; and for HCV: 1·64 [1·43-1·89; p<0·0001]; I2= 9·6%; n=14). For risk of HIV acquisition, the association for unstable housing (cRR 1·82 [1·13-2·95; p=0·014]; n=5) was higher than for homelessness (1·44 [1·13-1·83; p=0·0036]; n=12), whereas no difference was seen between these outcomes for risk of HCV acquisition (1·72 [1·48-1·99; p<0·0001] for unstable housing, 1·66 [1·37-2·00; p<0·0001] for homelessness).

INTERPRETATION

Homelessness and unstable housing are associated with increased risk of HIV and HCV acquisition among PWID. Our findings support the development of interventions that simultaneously address homelessness and unstable housing and HIV and HCV transmission in this population.

FUNDING

National Institute for Health Research, National Institute on Drug Abuse, National Institute of Allergy and Infectious Diseases, and Commonwealth Scholarship Commission.

Examining the gender composition of drug injecting initiation events: A mixed methods investigation of three North American contexts

BACKGROUND

Gender influences the health and social risks faced by individuals initiating drug injecting. Using mixed methods across three settings in North America, we investigated the gender composition of injection initiation events and the gendered risk environments in which they occurred.

METHODS

The PReventing Injecting by Modifying Existing Responses (PRIMER) study pooled data from three prospective community-recruited cohorts of people who inject drugs (PWID) in San Diego, USA, Vancouver, Canada, and Tijuana, Mexico. A qualitative subsample provided narrative data on their experiences of, and the contexts for, injection initiation events. Guided by Rhodes' risk environment framework, we examined the gender composition of initiation events stratified by city, and analyzed qualitative data using abductive thematic analyses.

RESULTS

Among 2,622 PWID (Tijuana: n = 531; San Diego: n = 352; Vancouver: n = 1,739), 112 (4.3%) reported providing initiation assistance to injection-naïve individuals in the previous six months. The proportion of gender concordant (e.g., male-male) initiation pairs varied, (χ2 = 10.32, p <0.001) with greater than expected concordance among pairs in Tijuana compared with those in Vancouver or San Diego. Sixty-one interviews provided context for the discrepancy across sites by highlighting the gendered injection initiation risk environments of prison/jail detention in Tijuana, intimate partnerships in San Diego, and overdose risk in Vancouver.

CONCLUSIONS

These results highlight how gender influences injection initiation events within spatial, social, and economic risk environments, and how this influence varies across settings. These findings can inform interventions to reduce the risk of injection initiation and related harms.

Is hepatitis C virus (HCV) elimination achievable among people who inject drugs in Tijuana, Mexico? A modeling analysis

BACKGROUND

In 2019, Mexico became the first Latin American country committed to hepatitis C virus (HCV) elimination, but the amount of intervention scale-up required is unclear. In Tijuana, HCV among people who inject drugs (PWID) is high; yet there is minimal and intermittent harm reduction, and involuntary exposure to compulsory abstinence programs (CAP) occurs which is associated with increased HCV risk. We determined what combination intervention scale-up can achieve HCV elimination among current and former PWID in Tijuana.

METHODS

We constructed a dynamic, deterministic model of HCV transmission, disease progression, and harm reduction among current and former PWID parameterized to Tijuana (~10,000 current PWID, 90% HCV seropositive, minimal opiate agonist therapy [OAT] or high coverage needle/syringe programs [HCNSP]). We evaluated the number of direct-acting antiviral (DAA) treatments needed from 2019 to achieve elimination targets (80% incidence reduction, 65% mortality reduction by 2030) with: (a) DAAs alone, (b) DAAs plus scale-up of OAT+HCNSP (up to 50% coverage of OAT and HCNSP separately, producing 25% of PWID receiving both), (c) DAAs plus CAP scale-up to 50%. Scenarios examined the number of DAAs required if prioritized to current PWID or provided regardless of current injection status, and impact of harm reduction interruptions.

RESULTS

Modeling suggests among ~30,000 current and former PWID in Tijuana, 16,160 (95%CI: 12,770-21,610) have chronic HCV. DAA scale-up can achieve the incidence target, requiring 770 treatments/year (95%CI: 640-970) if prioritized to current PWID. 40% fewer DAAs are required with OAT+HCNSP scale-up to 50% among PWID, whereas more are required with involuntary CAP scale-up. Both targets can only be achieved through treating both current and former PWID (1,710 treatments/year), and impact is reduced with harm reduction interruptions.

CONCLUSIONS

Elimination targets are achievable in Tijuana through scale-up of harm reduction and DAA therapy, whereas involuntary CAP and harm reduction interruptions hamper elimination.

Sex differences in the multilevel determinants of injection risk behaviours among people who inject drugs in Tijuana, Mexico

INTRODUCTION AND AIMS

HIV and hepatitis C virus transmission among people who inject drugs (PWID) is fuelled by personal and environmental factors that vary by sex. We studied PWID in Mexico to identify sex differences in multilevel determinants of injection risk.

DESIGN AND METHODS

From 2011 to 2013, 734 PWID (female: 277, male: 457) were enrolled into an observational cohort study in Tijuana. Participants completed interviews on injection and sexual risks. Utilising baseline data, we conducted multiple generalised linear models stratified by sex to identify factors associated with injection risk scores (e.g. frequency of injection risk behaviours).

RESULTS

For both sexes, difficult access to sterile syringes was associated with elevated injection risk (b = 1.24, 95% confidence interval [CI] 1.16-1.33), using syringes from a safe source (e.g. needle exchange programs) was associated with lower injection risk (b = 0.87, 95% CI 0.82-0.94), and for every one-unit increase in safe injection self-efficacy we observed a 20% decrease in injection risk (b = 0.80, 95% CI 0.76-0.84). Females had a higher safe injection self-efficacy score compared to males (median 2.83, interquartile range 2.2-3 vs. median 2.83, interquartile range 2-3; P = 0.01). Among females, incarceration (b = 1.22, 95% CI 1.09-1.36) and police confiscation of syringes in the past 6 months (b = 1.16, 95% CI 1.01-1.33) were associated with elevated injection risk. Among males, sex work (b = 1.16, 95% CI 1.04-1.30) and polysubstance use in the past 6 months (b = 1.22, 95% CI 1.13-1.31) were associated with elevated injection risk.

DISCUSSION AND CONCLUSIONS

Interventions to reduce HIV and hepatitis C virus transmission among PWID in Tijuana should be sex-specific and consider multilevel determinants of injection risk to create safer drug use environments.

Preferences and acceptability of law enforcement initiated referrals for people who inject drugs: a mixed methods analysis

BACKGROUND

Law enforcement officers (LEOs) come into frequent contact with people who inject drugs (PWID). Through service referrals, LEOs may facilitate PWID engagement in harm reduction, substance use treatment, and other health and supportive services. Little is known about PWID and LEO attitudes and concerns about service referrals, however. The objective of this mixed-methods study was to examine the alignment of service referral preferences and acceptability among PWID and LEOs in Tijuana, Mexico.

METHODS

We assessed service referral preferences and perceived likelihood of participation in health and social services, integrating data from structured questionnaires with 280 PWID and 306 LEOs, contextualized by semi-structured interviews and focus groups with 15 PWID and 17 LEOs enrolled in two parallel longitudinal cohorts in Tijuana, Mexico.

RESULTS

Among potential service referral options, both PWID (78%) and LEOs (88%) most frequently cited assistance with drug- and alcohol-use disorders. Over half of PWID and LEOs supported including harm reduction services such as syringe service programs, overdose prevention, and HIV testing. The majority of PWID supported LEO referrals to programs that addressed basic structural needs (e.g. personal care [62%], food assistance [61%], housing assistance [58%]). However, the proportion of LEOs (30-45%) who endorsed these service referrals was significantly lower (p <  0.01). Regarding referral acceptability, 71% of PWID reported they would be very likely or somewhat likely to make use of a referral compared to 94% of LEOs reporting that they thought PWID would always or sometimes utilize them. These results were echoed in the qualitative analysis, although practical barriers to referrals emerged, whereby PWID were less optimistic that they would utilize referrals compared to LEOs.

CONCLUSIONS

We identified strong support for LEO service referrals among both LEO and PWID respondents, with the highest preference for substance use treatment. LEO referral programs offer opportunities to deflect PWID contact with carceral systems while facilitating access to health and social services. However, appropriate investments and political will are needed to develop an evidence-based (integrated) service infrastructure.

Prevalence and correlates of obstructive lung disease among people who inject drugs, San Diego, California

BACKGROUND

Pulmonary tissue damage leading to obstructive lung disease (OLD) could result from intravenous administration of insoluble particles found in illicit drugs. This study described the prevalence and identified correlates of OLD among people who inject drugs (PWID).

METHODS

In 2012-2016, a community-based cohort of PWID who had injected within the past month were enrolled in a study to assess HIV, hepatitis C virus (HCV) andMycobacterium tuberculosis (Mtb) infections and their related risk factors. Data were obtained through face-to-face interviews, serological testing and spirometry. Baseline data were used for a cross-sectional analysis of the prevalence and correlates of OLD, defined as FEV1/FVC < 0.7. Univariate and multivariable logistic regression were used to identify factors associated with OLD.

RESULTS

Among 516 participants who had complete spirometry and interview results, the mean age was 43.3 years, 73.6 % were male, 9.5 % were Black, 91.1 % smoked cigarettes and 18.2 % had OLD. Few (9.6 %) PWID with OLD reported a previous diagnosis of COPD although many (44.7 %) reported related symptoms. Black race (AOR = 2.66, 95 %CI: 1.37, 5.17), pack-years smoked (AOR = 1.06/5 years, 95 %CI: 1.01, 1.12), and duration of injection drug use (AOR = 1.13, 95 %CI: 1.01, 1.27) were independently associated with OLD after controlling for age.

CONCLUSIONS

The prevalence of OLD was high in this cohort and associated with Black race and cigarette smoking-known risk factors. In addition, OLD prevalence increased with greater duration of injection drug use, suggesting a link between cumulative exposure to injected insoluble particles and OLD. Further examination of these adulterants and lung pathology are needed.

Sex Work as a Mediator Between Female Gender and Incident HIV Infection Among People Who Inject Drugs in Tijuana, Mexico

We studied mechanisms driving gender differences in HIV incidence among 651 women and men who inject drugs (PWID) in Tijuana, Mexico, hypothesizing that sex work will mediate the association between female gender and HIV incidence. Of 43 HIV seroconversions occurring between 2011 and 2018, 8.8% were among females and 5.2% among males. HIV incidence density was significantly higher among females versus males (1.75 per 100 person years [PY], 95% CI 1.16-2.66, vs. 0.95 per 100 PY, 95% CI 0.62-1.47). Factors significantly associated with HIV seroconversion were: sex work (adjusted hazard ratio [aHR] = 2.25, 95% CI 1.05-4.80); methamphetamine injection (aHR = 2.30, 95% CI 1.12-4.73); and methamphetamine and heroin co-injection in the past six months (aHR = 2.26, 95% CI 1.23-4.15). In mediation analyses, sex work mediated a substantial proportion (84.3%) of the association between female gender and HIV incidence. Interventions should target female PWID who engage in sex work to reduce gender-related disparities in HIV incidence.

The role of gender and power dynamics in injection initiation events within intimate partnerships in the US-Mexico border region

Women's initiation into injection drug use often establishes a pattern of risk following first injection. This study explored sources of gendered power dynamics in injection initiation experiences for people who inject drugs. A qualitative subsample from two prospective community-recruited cohorts of people who inject drugs in San Diego and Tijuana provided data on the contexts surrounding injection initiation processes. Intimate partnerships were identified in initiation; sub-themes were identified drawing on three concepts within the theory of gender and power. With reference to sexual division of labour, men were often responsible for access to resources in partnerships across both contexts, although there were limited accounts of women obtaining those resources. Extending the structure of power, women in San Diego reported that initiation events involving an intimate partner occurred from a position of vulnerability but expressed greater agency when providing initiation assistance. With regard to structure of cathexis, social norms proscribing injection initiation among women exist, particularly in Tijuana. Gendered power dynamics are a multifaceted component of injection initiation events, especially for women in intimate partnerships. These results stress the need for nuance in understanding the intersection of risk, gender and harm reduction within injection initiation events across socio-cultural contexts.

Self-perception of assisting with future injection drug initiation: The influence of relationships in the process of drug injecting initiation

INTRODUCTION AND AIMS

People who inject drugs (PWID) play critical roles in assisting others into injection drug use (IDU) initiation. Understanding perceptions of PWID's risk of initiating others is needed to inform interventions for prevention. The objective was to examine factors associated with self-perception of assisting with future IDU initiation events. The primary variables of interest are the relationships of PWID with the person(s) they assisted and their reasons for previously providing initiation assistance.

DESIGN AND METHODS

Data from Preventing Injecting by Modifying Existing Responses, a multi-site prospective community-recruited cohort study, were analysed. Analyses were restricted to PWID who reported ever providing IDU initiation assistance. Site-specific (Vancouver, Canada [n = 746]; San Diego, USA [n = 95] and Tijuana, Mexico [n = 92]) multivariable logistic regression analyses were performed to determine factors associated with self-perception of assisting with future IDU initiation.

RESULTS

Having provided IDU initiation assistance to a family member or intimate partner decreased the odds of self-perception of assisting with future IDU initiation in Vancouver (AOR = 0.4; 95% CI 0.2-0.8); however, previous IDU initiation assistance to an 'other' increased the odds of self-perception of assisting with future IDU in Tijuana (AOR = 12.0; 95% CI 2.1-70.3). Daily IDU (Vancouver: AOR = 3.7; 95% CI 2.1-6.4) and less than daily IDU (San Diego: AOR = 5.9; 95% CI 1.3-27.1) (Vancouver: AOR = 2.6; 95% CI 1.4-2.9) were associated with increased self-perception of assisting with future IDU compared to current non-injectors.

DISCUSSION AND CONCLUSIONS

Relationship to past initiates and IDU frequency might increase PWID's self-perception of assisting with future IDU. Interventions focused on social support and reducing IDU frequency may decrease occurrences of IDU initiation assistance.

Modelling integrated antiretroviral treatment and harm reduction services on HIV and overdose among people who inject drugs in Tijuana, Mexico

INTRODUCTION

The HIV epidemic in Tijuana, Mexico is concentrated in key populations, including people who inject drugs (PWID). However, HIV interventions among PWID are minimal, and federal funding was provided for compulsory abstinence programmes associated with HIV and overdose. Alternatively, opioid agonist therapy reduces overdose, reincarceration, HIV, while improving antiretroviral therapy (ART) outcomes. We assessed potential impact and synergies of scaled-up integrated ART and opioid agonist therapy, compared to scale-up of each separately, and potential harms of compulsory abstinence programmes on HIV and fatal overdose among PWID in Tijuana.

METHODS

We developed a dynamic model of HIV transmission and overdose among PWID in Tijuana. We simulated scale-up of opioid agonist therapy from zero to 40% coverage among PWID. We evaluated synergistic benefits of an integrated harm reduction and ART scale-up strategy (40% opioid agonist therapy coverage and 10-fold ART recruitment), compared to scale-up of each intervention alone or no scale-up of low coverage ART and no harm reduction). We additionally simulated compulsory abstinence programmes (associated with 14% higher risk of receptive syringe sharing and 76% higher odds of overdose) among PWID.

RESULTS

Without intervention, HIV incidence among PWID could increase from 0.72 per 100 person-years (PY) in 2020 to 0.92 per 100 PY in 2030. Over ten years, opioid agonist therapy scale-up could avert 31% (95% uncertainty interval (UI): 18%, 46%) and 22% (95% UI: 10%, 28%) new HIV infections and fatal overdoses, respectively, with the majority of HIV impact from the direct effect on HIV transmission due to low ART coverage. Integrating opioid agonist therapy and ART scale-up provided synergistic benefits, with opioid agonist therapy effects on ART recruitment/retention averting 9% more new infections compared to ART scale-up alone. The intervention strategy could avert 48% (95% UI: 26%, 68%) of new HIV infections and one-fifth of fatal overdoses over ten years. Conversely, compulsory abstinence programmes could increase HIV and overdoses.

CONCLUSIONS

Integrating ART with opioid agonist therapy could provide synergistic benefits and prevent HIV and overdoses among PWID in Tijuana, whereas compulsory abstinence programmes could cause harm. Policymakers should consider the benefits of integrating harm reduction and HIV services for PWID.

Drugs, discipline and death: Causes and predictors of mortality among people who inject drugs in Tijuana, 2011-2018

BACKGROUND

People who inject drugs (PWID) experience multiple risk factors for mortality; yet, we know little about causes of death among PWID in Tijuana, Mexico, an area with high levels of injecting and changes in policy/law enforcement responses to substance use. This study examines rates, causes, and predictors of mortality among Tijuana PWID.

METHODS

Data come from a community-based cohort of PWID aged ≥18 who injected drugs in the past month. Mortality was confirmed by death certificate over 78 months during 2011-2018. Predictors of mortality were identified using time-updated Cox regression, controlling for age.

RESULTS

Among 734 participants, there were 130 deaths (54 confirmed, 76 unconfirmed), with an incidence rate of 17.74 deaths per 1000 person-years for confirmed deaths (95% Confidence Interval (CI)=13.01, 22.48) and 39.52 for unconfirmed deaths (CI=32.72, 46.31). Confirmed deaths resulted from homicide/trauma (26%), overdose (26%), septic shock (18%) and HIV-related causes (9%). In multivariable analysis of confirmed deaths, baseline HIV seropositivity (adjusted Hazard Ratio [aHR]=6.77, CI=1.98, 23.17), incident HIV infection (aHR=3.19, CI=1.02, 9.96), and number of times being beaten by police in the past 6 months at baseline (aHR=1.08 per time, CI=1.04, 1.12) were predictive of death; whereas, injection cessation for 6+ months during time at risk (aHR=0.25, CI=0.33, 0.79) was protective.

CONCLUSION

In addition to overdose and HIV prevention efforts, attention to structural conditions that potentiate mortality is needed, including improved access to medication-assisted treatment to support injection cessation and a shift from police as a source of harm to harm reduction.

Prevalence and Correlates of Injecting with Visitors from the United States Among People Who Inject Drugs in Tijuana, Mexico

Cross-border infectious disease transmission is a concern related to drug tourism from the U.S. to Mexico. We assessed this risk among people who inject drugs (PWID) in Tijuana, Mexico. We measured the prevalence and identified correlates of injecting with PWID visiting from the U.S. among PWID in Tijuana using univariable and multivariable logistic regression. Of 727 participants, 18.5% injected during the past 6 months in Mexico with U.S. PWID described mostly as friends (63%) or acquaintances (26%). Injecting with U.S. PWID was independently associated with higher education [adjusted odds ratio (aOR) = 1.13/year], deportation from the U.S. (aOR = 1.70), younger age at first injection (aOR = 0.96/year), more lifetime overdoses (aOR = 1.08), and, in the past 6 months, backloading (aOR = 4.00), syringe confiscation by the police (aOR = 3.02) and paying for sex (aOR = 2.98; all p-values < 0.05). Nearly one-fifth of PWID in Tijuana recently injected with U.S. PWID, and their reported risk behaviors could facilitate cross-border disease transmission.

Opioid agonist treatment scale-up and the initiation of injection drug use: A dynamic modeling analysis

BACKGROUND

Injection drug use (IDU) is associated with multiple health harms. The vast majority of IDU initiation events (in which injection-naïve persons first adopt IDU) are assisted by a person who injects drugs (PWID), and as such, IDU could be considered as a dynamic behavioral transmission process. Data suggest that opioid agonist treatment (OAT) enrollment is associated with a reduced likelihood of assisting with IDU initiation. We assessed the association between recent OAT enrollment and assisting IDU initiation across several North American settings and used dynamic modeling to project the potential population-level impact of OAT scale-up within the PWID population on IDU initiation.

METHODS AND FINDINGS

We employed data from a prospective multicohort study of PWID in 3 settings (Vancouver, Canada [n = 1,737]; San Diego, United States [n = 346]; and Tijuana, Mexico [n = 532]) from 2014 to 2017. Site-specific modified Poisson regression models were constructed to assess the association between recent (past 6 month) OAT enrollment and history of ever having assisted an IDU initiation with recently assisting IDU initiation. Findings were then pooled using linear mixed-effects techniques. A dynamic transmission model of IDU among the general population was developed, stratified by known factors associated with assisting IDU initiation and relevant drug use behaviors. The model was parameterized to a generic North American setting (approximately 1% PWID) and used to estimate the impact of increasing OAT coverage among PWID from baseline (approximately 21%) to 40%, 50%, and 60% on annual IDU initiation incidence and corresponding PWID population size across a decade. From Vancouver, San Diego, and Tijuana, respectively, 4.5%, 5.2%, and 4.3% of participants reported recently assisting an IDU initiation, and 49.4%, 19.7%, and 2.1% reported recent enrollment in OAT. Recent OAT enrollment was significantly associated with a 45% lower likelihood of providing recent IDU initiation assistance among PWID (relative risk [RR] 0.55 [95% CI 0.36-0.84], p = 0.006) compared to those not recently on OAT. Our dynamic model predicts a baseline mean of 1,067 (2.5%-97.5% interval [95% I 490-2,082]) annual IDU initiations per 1,000,000 individuals, of which 886 (95% I 406-1,750) are assisted by PWID. Based on our observed statistical associations, our dynamic model predicts that increasing OAT coverage from approximately 21% to 40%, 50%, or 60% among PWID could reduce annual IDU initiations by 11.5% (95% I 2.4-21.7), 17.3% (95% I 5.6-29.4), and 22.8% (95% I 8.1-36.8) and reduce the PWID population size by 5.4% (95% I 0.1-12.0), 8.2% (95% I 2.2-16.9), and 10.9% (95% I 3.2-21.8) relative to baseline, respectively, in a decade. Less impact occurs when the protective effect of OAT is diminished, when a greater proportion of IDU initiations are unassisted by PWID, and when average IDU career length is longer. The study's main limitations are uncertainty in the causal pathway between OAT enrollment and assisting with IDU initiation and the use of a simplified model of IDU initiation.

CONCLUSIONS

In addition to its known benefits on preventing HIV, hepatitis C virus (HCV), and overdose among PWID, our modeling suggests that OAT scale-up may also reduce the number of IDU initiations and PWID population size.

Addressing the context and consequences of substance use, misuse, and dependence: A global imperative

In an Editorial, Guest Editors Alexander Tsai, Margarita Alegria and Steffanie Strathdee discuss the accompanying Special Issue on Substance Use, Misuse and Dependence.

Identification of a Syndemic of Blood-Borne Disease Transmission and Injection Drug Use Initiation at the US-Mexico Border

BACKGROUND

Efforts to prevent injection drug use (IDU) are increasingly focused on the role that people who inject drugs (PWID) play in the assistance with injection initiation. We studied the association between recent (ie, past 6 months) injection-related HIV risk behaviors and injection initiation assistance into IDU among PWID in the US-Mexico border region.

SETTING

Preventing Injecting by Modifying Existing Responses (PRIMER) is a multicohort study assessing social and structural factors related to injection initiation assistance. This analysis included data collected since 2014 from 2 participating cohorts in San Diego and Tijuana.

METHODS

Participants were 18 years and older and reported IDU within the month before study enrollment. Logistic regression analyses were conducted to assess the association between recent injection-related HIV risk behaviors (eg, distributive/receptive syringe sharing, dividing drugs in a syringe, and paraphernalia sharing) and recent injection initiation assistance.

RESULTS

Among 892 participants, 41 (4.6%) reported recently providing injection initiation assistance. In multivariable analysis adjusting for potential confounders, reporting a higher number of injection-related risk behaviors was associated with an increased odds of recently assisting others with injection initiation (adjusted odds ratio per risk behavior: 1.3; 95% confidence interval: 1.0 to 1.6, P = 0.04).

CONCLUSIONS

PWID who recently engaged in one or more injection-related HIV risk behavior were more likely to assist others in injection initiation. These results stress the syndemic of injection initiation and risk behaviors, which indicates that prevention of injection-related HIV risk behaviors might also reduce the incidence of injection initiation.

Attitudes towards safe consumption sites among police and people with lived experience in Tijuana, Mexico: initial report from the field

Introduction. Mexico northern border has high levels of heroin use. For more than 10 years, the country has implemented several harm reduction interventions to reduce the risks associated with drug use. New strategies such as Safe Consumption Sites (SCS) must be considered as a next step to service vulnerable populations and increase their health outcomes. Objective. This report seeks to measure and compare attitudes on a potential SCS intervention in Tijuana among police and people with lived experience (PLE) in heroin use in the city. Method. Two parallel studies on police practices and everyday experiences of heroin users in Tijuana were able to ask similar questions about attitudes toward SCS and its implementation in the city. They conducted quantitative interviews with 771 active police officers and 200 PLE while in rehabilitation services. Results. Both groups showed a high personal support for SCS of nearly 82% and a perceived implementation success around 80%. Officers reported 58.9% peer support for SCS while PLE 79%. Around 76% of both groups agreed that a SCS would help to improve their personal health. Finally, 86.2% of the officers would refer people to a SCS while 62.5% of PLE would use the service. Discussion and conclusions. The strong positive attitudes from police officers and PLE towards SCS in the city of Tijuana reported in both studies indicate the possibility of a successful implementation of a SCS. This intervention would represent an innovative way to protect PLE from police harassment and victimization, helping reduce HIV and HCV risk behaviors while improving community health.

Interactive Versus Video-Based Training of Police to Communicate Syringe Legality to People Who Inject Drugs: The SHIELD Study, Mexico, 2015-2016

Objectives. To assess how instructional techniques affect officers' intent to communicate syringe legality during searches in Tijuana, Mexico, where pervasive syringe confiscation potentiates risk of HIV and HCV among people who inject drugs (PWID) and of occupational needle-stick injury among police. Methods. Using the SHIELD (Safety and Health Integration in the Enforcement of Laws on Drugs) model, Tijuana police underwent training to encourage communication of syringe possession legality to PWID. Trainees received either passive video or interactive role-play exercise on safer search techniques. We used logistic regression to assess the training's impact on self-reported intent to communicate syringe legality by training type and gender. Results. Officers (n = 1749) were mostly men (86%) assigned to patrol (84%). After the training, intent to communicate the law improved markedly: from 20% to 39% (video group) and 20% to 58% (interactive group). Gender and training type significantly predicted intent to communicate syringe legality. Male and female officers' adjusted odds ratios in the interactive group were 5.37 (95% confidence interval [CI] = 4.56, 6.33) and 9.16 (95% CI = 5.88, 14.28), respectively, after the training. Conclusions. To more effectively persuade police to endorse harm reduction and occupational safety practices, police trainings should include interactive elements.

"Somebody Is Gonna Be Hurt": Involuntary Drug Treatment in Mexico

Involuntary drug treatment (IDT) is ineffective in decreasing drug use, yet it is a common practice. In Mexico, there are not enough professional residential drug treatment programs, and both voluntary and involuntary drug treatment is often provided by non-evidence based, non-professional programs. We studied the experiences of people who inject drugs (PWID) in Tijuana who were taken involuntarily to drug centers under the auspices of a federally funded police operation. We provide insight into how the health, wellbeing, human rights, dignity, and security of PWID ought to be at the center of international drug policies included in universal health care systems.

Evaluating the impact of global fund withdrawal on needle and syringe provision, cost and use among people who inject drugs in Tijuana, Mexico: a costing analysis

OBJECTIVE

From 2011 to 2013, the Global Fund (GF) supported needle and syringe programmes in Mexico to prevent transmission of HIV among people who inject drugs. It remains unclear how GF withdrawal affected the costs, quality and coverage of needle and syringe programme provision.

DESIGN

Costing study and longitudinal cohort study.

SETTING

Tijuana, Mexico.

PARTICIPANTS

Personnel from a local needle and syringe programme (n=6) and people who inject drugs (n=734) participating in a longitudinal study.

PRIMARY OUTCOME MEASURES

Provision of needle and syringe programme services and cost (per contact and per syringe distributed, in 2017 $USD) during GF support (2012) and after withdrawal (2015/16). An additional outcome included needle and syringe programme utilisation from a concurrent cohort of people who inject drugs during and after GF withdrawal.

RESULTS

During the GF period, the needle and syringe programme distributed 55 920 syringes to 932 contacts (60 syringes/contact) across 14 geographical locations. After GF withdrew, the needle and syringe programme distributed 10 700 syringes to 2140 contacts (five syringes/contact) across three geographical locations. During the GF period, the cost per harm reduction contact was approximately 10-fold higher compared with after GF ($44.72 vs $3.81); however, the cost per syringe distributed was nearly equal ($0.75 vs $0.76) due to differences in syringes per contact and reductions in ancillary kit components. The mean log odds of accessing a needle and syringe programme in the post-GF period was significantly lower than during the GF period (p=0.02).

CONCLUSIONS

Withdrawal of GF support for needle and syringe programme provision in Mexico was associated with a substantial drop in provision of sterile syringes, geographical coverage and recent clean syringe utilisation among people who inject drugs. Better planning is required to ensure harm reduction programme sustainability is at scale after donor withdrawal.

"Another Person Was Going to Do It": The Provision of Injection Drug Use Initiation Assistance in a High-Risk U.S.-Mexico Border Region

Background: Persons who inject drugs (PWID) play a key role in assisting others' initiation into injection drug use (IDU). We aimed to explore the pathways and socio-structural contexts for this phenomenon in Tijuana, Mexico, a border setting marked by a large PWID population with limited access to health and social services. Methods: Preventing Injecting by Modifying Existing Responses (PRIMER) is a multi-cohort study assessing socio-structural factors associated with PWID assisting others into initiating IDU. Semi-structured qualitative interviews in Tijuana included participants ≥18 years old, who reported IDU within the month prior to cohort enrollment and ever initiating others into IDU. Purposive sampling ensured a range of drug use experiences and behaviors related to injection initiation assistance. Thematic analysis was used to develop recurring and significant data categories. Results: Twenty-one participants were interviewed (8 women, 13 men). Broadly, participants considered public injection to increase curiosity about IDU. Many considered transitioning into IDU as inevitable. Emergent themes included providing assistance to mitigate overdose risk and to protect initiates from being taken advantage of by others. Participants described reluctance in engaging in this process. For some, access to resources (e.g., shared drugs or a monetary fee) was a motivator to initiate others. Conclusion: In Tijuana, public injection and a lack of harm reduction services are perceived to fuel the incidence of IDU initiation and to incentivize PWID to assist in injection initiation. IDU prevention efforts should address structural factors driving PWID participation in IDU initiation while including PWID in their development and implementation.

Where Is the Opioid Use Epidemic in Mexico? A Cautionary Tale for Policymakers South of the US-Mexico Border

In North America, opioid use and its harms have increased in the United States and Canada over the past 2 decades. However, Mexico has yet to document patterns suggesting a higher level of opioid use or attendant harms.Historically, Mexico has been a country with low-level use of opioids, although heroin use has been documented. Low-level opioid use is likely attributable to structural, cultural, and individual factors. However, a range of dynamic factors may be converging to increase the use of opioids: legislative changes to opioid prescribing, national health insurance coverage of opioids, pressure from the pharmaceutical industry, changing demographics and disease burden, forced migration and its trauma, and an increase in the production and trafficking of heroin. In addition, harm-reduction services are scarce.Mexico may transition from a country of low opioid use to high opioid use but has the opportunity to respond effectively through a combination of targeted public health surveillance of high-risk groups, preparation of appropriate infrastructure to support evidence-based treatment, and interventions and policies to avoid a widespread opioid use epidemic.

The effect of public health-oriented drug law reform on HIV incidence in people who inject drugs in Tijuana, Mexico: an epidemic modelling study

BACKGROUND

As countries embark on public health-oriented drug law reform, health impact evaluations are needed. In 2012, Mexico mandated the narcomenudeo reform, which depenalised the possession of small amounts of drugs and instituted drug treatment instead of incarceration. We investigated the past and future effect of this drug law reform on HIV incidence in people who inject drugs in Tijuana, Mexico.

METHODS

In this epidemic modelling study, we used data from the El Cuete IV cohort study to develop a deterministic model of injecting and sexual HIV transmission in people who inject drugs in Tijuana between 2012 and 2030. The population was stratified by sex, incarceration status, syringe confiscation by the police, HIV stage, and exposure to drug treatment or rehabilitation (either opioid agonist treatment or compulsory drug abstinence programmes). We modelled the effect of these exposures on HIV risk in people who inject drugs, estimating the effect of observed and potential future reform enforcement levels.

FINDINGS

In 2011, prior to the narcomenudeo reform, 547 (75%) of 733 people who inject drugs in the El Cuete cohort reported having ever been incarcerated, on average five times since starting injecting. Modelling estimated the limited reform implementation averted 2% (95% CI 0·2-3·0) of new HIV infections in people who inject drugs between 2012 and 2017. If implementation reduced incarceration in people who inject drugs by 80% from 2018 onward, 9% (95% CI 4-16) of new HIV infections between 2018 and 2030 could be averted, with 21% (10-33) averted if people who inject drugs were referred to opioid agonist treatment instead of being incarcerated. Referral to compulsory drug abstinence programmes instead of prison could have a lower or potentially negative impact with -2% (95% CI -23 to 9) infections averted.

INTERPRETATION

Mexican drug law reform has had a negligible effect on the HIV epidemic among people who inject drugs in Tijuana. However, appropriate implementation could markedly reduce HIV incidence if linked to opioid agonist treatment. Unfortunately, compulsory drug abstinence programmes are the main type of drug rehabilitation available and their expansion could potentially increase HIV transmission.

FUNDING

National Institute on Drug Abuse, UC San Diego Center for AIDS Research.

Molecular Analysis of Human Immunodeficiency Virus Type 1 (HIV-1)-Infected Individuals in a Network-Based Intervention (Transmission Reduction Intervention Project): Phylogenetics Identify HIV-1-Infected Individuals With Social Links

Background

The Transmission Reduction Intervention Project (TRIP) is a network-based intervention that aims at decreasing human immunodeficiency virus type 1 (HIV-1) spread. We herein explore associations between transmission links as estimated by phylogenetic analyses, and social network-based ties among persons who inject drugs (PWID) recruited in TRIP.

Methods

Phylogenetic trees were inferred from HIV-1 sequences of TRIP participants. Highly supported phylogenetic clusters (transmission clusters) were those fulfilling 3 different phylogenetic confidence criteria. Social network-based ties (injecting or sexual partners, same venue engagement) were determined based on personal interviews, recruitment links, and field observation.

Results

TRIP recruited 356 individuals (90.2% PWID) including HIV-negative controls; recently HIV-infected seeds; long-term HIV-infected seeds; and their social network members. Of the 150 HIV-infected participants, 118 (78.7%) were phylogenetically analyzed. Phylogenetic analyses suggested the existence of 13 transmission clusters with 32 sequences. Seven of these clusters included 14 individuals (14/32 [43.8%]) who also had social ties with at least 1 member of their cluster. This proportion was significantly higher than what was expected by chance.

Conclusions

Molecular methods can identify HIV-infected people socially linked with another person in about half of the phylogenetic clusters. This could help public health efforts to locate individuals in networks with high transmission rates.

Estratégias de redução de danos no uso prejudicial de álcool e outras drogas: revisão de literatura

O presente estudo traz uma sistematização acerca de experiências de atenção à saúde a pessoas que fazem uso prejudicial de álcool e outras drogas que têm por base as diretrizes da redução de danos no Brasil e no mundo. Foi realizado um levantamento bibliográfico em publicações de língua portuguesa e inglesa dos últimos dez anos hospedadas nas bases de dados SciELO, Lilacs, Medline e PsycINFO. Após a seleção do corpus, recorreu-se à metassíntese a fim de integrar o material obtido. Foi possível identificar e analisar avanços e impasses na implantação de estratégias de redução de danos, bem como comparar as diferentes abordagens identificadas nos serviços e ações de cuidado oferecidas aos usuários. Nota-se que a Redução de Danos tem se consolidado como estratégia de prevenção e tratamento e, dessa forma, torna-se imprescindível ampliar as produções acadêmica e científica na área.

Increased non-fatal overdose risk associated with involuntary drug treatment in a longitudinal study with people who inject drugs

AIM

To assess the effect of involuntary drug treatment (IDT) on non-fatal overdose among people who inject drugs (PWID).

DESIGN

Longitudinal study.

SETTING

Tijuana, Mexico.

PARTICIPANTS

Baseline sample of 671 PWID included 258 (38.4%) women and 413 (61.6%) men.

MEASUREMENTS

Primary independent variables were reported recent (i.e. past 6 months) non-fatal overdose event (dependent variable) and IDT. Substance use the day of the non-fatal overdose was also examined.

FINDINGS

From 2011 to 2017, 213 participants (31.7%) reported a recent non-fatal overdose and 103 (15.4%) reported recent IDT. Heroin, in combination with methamphetamine and tranquilizers, were the drugs most reported at the day of the event. IDT significantly increased the odds of reporting a non-fatal overdose event [adjusted odds ratio (aOR) = 1.76; 95% confidence interval (CI) = 1.04-2.96]. Odds of non-fatal overdose also increased independently for each additional injection per day (aOR = 1.05; 95% CI = 1.02-1.08), recent tranquilizer use (aOR = 1.92; 95% CI = 1.41-2.61) and using hit doctors (aOR = 1.68; 95% CI = 1.29-2.18) and decreased with age (aOR = 0.97 per year, 95% CI = 0.95-0.99).

CONCLUSIONS

Recent involuntary drug treatment in Mexico is a risk factor for non-fatal drug overdose.

Cost of provision of opioid substitution therapy provision in Tijuana, Mexico

BACKGROUND

Mexico recently enacted drug policy reform to decriminalize possession of small amounts of illicit drugs and mandated that police refer identified substance users to drug treatment. However, the economic implications of drug treatment expansion are uncertain. We estimated the costs of opioid substitution therapy (OST) provision in Tijuana, Mexico, where opioid use and HIV are major public health concerns.

METHODS

We adopted an economic health care provider perspective and applied an ingredients-based micro-costing approach to quantify the average monthly cost of OST (methadone maintenance) provision at two providers (one private and one public) in Tijuana, Mexico. Costs were divided by type of input (capital, recurrent personnel and non-personnel). We defined "delivery cost" as all costs except for the methadone and compared total cost by type of methadone (powdered form or capsule). Cost data were obtained from interviews with senior staff and review of expenditure reports. Service provision data were obtained from activity logs and senior staff interviews. Outcomes were cost per OST contact and cost per person month of OST. We additionally collected information on patient charges for OST provision from published rates.

RESULTS

The total cost per OST contact at the private and public sites was $3.12 and $5.90, respectively, corresponding to $95 and $179 per person month of OST. The costs of methadone delivery per OST contact were similar at both sites ($2.78 private and $3.46 public). However, cost of the methadone itself varied substantially ($0.34 per 80 mg dose [powder] at the private site and $2.44 per dose [capsule] at the public site). Patients were charged $1.93-$2.66 per methadone dose.

CONCLUSIONS

The cost of OST provision in Mexico is consistent with other upper-middle income settings. However, evidenced-based (OST) drug treatment facilities in Mexico are still unaffordable to most people who inject drugs.

Comparing risk environments for HIV among people who inject drugs from three cities in Northern Mexico

Background

A large body of research has investigated the rise of injection drug use and HIV transmission in Tijuana and Ciudad Juarez (CJ). However, little is known about the dynamics of injecting in Hermosillo. This study compares drug-related behaviors and risk environment for HIV of people who inject drugs (PWID) across Tijuana, CJ, and Hermosillo to identify factors that could explain differences in HIV prevalence.

Methods

Data from Tijuana belong to a prospective study (El Cuete IV). Data from Hermosillo and Ciudad Juarez belong to a cross-sectional study. Both studies collected data in places where PWID spend time. All participants completed quantitative behavioral and serological testing for HIV. Datasets were merged using only comparable variables. Descriptive statistics tests were used to compare sociodemographic and behavioral characteristics of people who inject drugs PWID sampled in each city. A logistic regression model was built to identify factors independently associated with the likelihood of reporting receptive syringe sharing in the past 6 months.

Results

A total of 1494 PWID provided data between March 2011 and May 2012. HIV prevalence differed significantly between participants in Tijuana (4.2%), CJ (7.7%), and Hermosillo (5.2%; p < 0.05). PWID from Hermosillo reported better living conditions, less frequency of drug injection, and lower prevalence of syringe sharing (p < 0.01). PWID from CJ reported a higher prevalence of syringe sharing and confiscation by police (p < 0.01). In a multivariable logistic regression model, living in Hermosillo compared to Tijuana (adjusted odds ratio [AOR] = 0.42, 95% confidence interval [CI] 0.29–0.61) and being female (AOR = 0.61, 95% CI 0.45–0.83) were protective against syringe sharing. Having used crystal meth (AOR = 1.62, 95% CI 1.24–2.13, p = 0.001), having experienced syringe confiscation by police in the last 6 months (AOR = 1.78, 95% CI 1.34–2.40), and lower perception of syringe availability (AOR = 2.15, 95% CI 1.59–2.91) were significantly associated with syringe sharing (p < 0.05).

Conclusions

Differences in HIV prevalence across cities reflect mainly differences in risk environments experienced by PWID, shaped by police practices, access to injection equipment, and dynamics of drug markets. Findings highlight the importance of ensuring sterile syringe availability through harm reduction services and a human rights approach to drug harms in northern Mexico and to generate better understanding of local dynamics and contexts of drug use for designing proper harm reduction programs.

A fragmented code: The moral and structural context for providing assistance with injection drug use initiation in San Diego, USA

BACKGROUND

Injection drug use initiation is shaped by social networks and structural contexts, with people who inject drugs often assisting in this process. We sought to explore the norms and contexts linked to assisting others to initiate injection drug use in San Diego, USA, to inform the development of structural interventions to prevent this phenomenon.

METHODS

We undertook qualitative interviews with a purposive sample of people who inject drugs and had reported assisting others to initiate injection (n = 17) and a sub-sample of people who inject drugs (n = 4) who had not reported initiating others to triangulate accounts. We analyzed data thematically and abductively.

RESULTS

Respondents' accounts of providing initiation assistance were consistent with themes and motives reported in other contexts: of seeking to reduce harm to the 'initiate', responding to requests for help, fostering pleasure, accessing resources, and claims that initiation assistance was unintentional. We developed analysis of these themes to explore initiation assistance as governed by a 'moral code'. We delineate a fragmented moral code which includes a range of meanings and social contexts that shape initiation assistance. We also show how assistance is happening within a structural context that limits discussion of injection drug use, reflecting a prevailing silence on drug use linked to stigma and criminalization.

CONCLUSIONS

In San Diego, the assistance of others to initiate injection drug use is governed by a fragmented moral code situated within particular social norms and contexts. Interventions that address the social and structural conditions shaped by and shaping this code may be beneficial, in tandem with efforts to support safe injection and the reduction of injection-related harms.

Cross-border migration and initiation of others into drug injecting in Tijuana, Mexico

INTRODUCTION AND AIMS

Efforts to prevent injection drug use (IDU) are increasingly focusing on the role that people who inject drugs (PWID) play in facilitating the entry of others into this behaviour. This is particularly relevant in settings experiencing high levels of IDU, such as Mexico's northern border region, where cross-border migration, particularly through forced deportation, has been found to increase a range of health and social harms related to injecting.

DESIGN AND METHODS

PWID enrolled in a prospective cohort study in Tijuana, Mexico, since 2011 were interviewed semi-annually, which solicited responses on their experiences initiating others into injecting. Univariate and multivariable logistic regression analyses were conducted at the Preventing Injection by Modifying Existing Responses (PRIMER) baseline, with the dependent variable defined as reporting ever initiating others into injection. The primary independent variable was lifetime deportation from the USA to Mexico.

RESULTS

Among 532 participants, 14% (n = 76) reported initiating others into injecting, the majority of participants reporting initiating acquaintances (74%, n = 56). In multivariable analyses, initiating others into injecting was independently associated with reporting living in the USA for 1-5 years [adjusted odds ratio (AOR) = 2.42; 95% confidence interval (CI) 1.22-4.79, P = 0.01], and methamphetamine and heroin injection combined (AOR = 3.67; 95% CI 1.11-12.17, P = 0.03). Deportation was not independently associated with initiating others into injecting.

DISCUSSION AND CONCLUSIONS

The impact of migration needs to be considered within binational programming seeking to prevent the expansion of epidemics of injecting and HIV transmission among mobile populations residing in the Mexico-USA border region.

Predictors of injecting cessation among a cohort of people who inject drugs in Tijuana, Mexico

INTRODUCTION

Little is known about the cessation of injecting drug use (IDU) among people who inject drugs (PWID) in low and middle-income settings, where access to effective interventions for reducing drug use (e.g., opioid substitution treatment; OST), may be limited. We measured the incidence and identified predictors of IDU cessation among a cohort of PWID in Tijuana, Mexico.

METHODS

Data were drawn from 621 participants in Proyecto El Cuete IV, a prospective cohort of PWID recruited in 2011 and interviewed biannually to 2016. A multivariable Extended Cox model was constructed to identify socio-demographic, drug use, risk environment and health-related predictors of IDU cessation (no IDU for ≥six months).

RESULTS

141 participants (23%) reported at least one IDU cessation event during follow-up. The crude IDU cessation rate was 7.3 per 100 person-years (95% Confidence Interval [CI]: 6.2-8.7). IDU cessation was negatively associated with injecting at least daily on average and heroin/methamphetamine co-injection in the past six months, and positively associated with testing HIV positive at baseline, being on methadone maintenance therapy in the past six months, and recent arrest. Concern for personal safety was also independently associated with IDU cessation.

CONCLUSIONS

The rate of IDU cessation among PWID in Tijuana was low. These findings underscore the importance of expansion of services including OST to help reduce drug use and facilitate IDU cessation for those who wish to do so. In this setting, interventions addressing individual-level economic barriers as well as broader social and structural barriers to harm reduction services are integral.

Mycobacterium tuberculosis infection among persons who inject drugs in San Diego, California

BACKGROUND

Persons who inject drugs (PWID) might be at increased risk for Mycobacterium tuberculosis infection and reactivation of latent tuberculous infection (LTBI) due to their injection drug use.

OBJECTIVES

To determine prevalence and correlates of M. tuberculosis infection among PWID in San Diego, California, USA.

METHODS

PWID aged 18 years underwent standardized interviews and serologic testing using an interferon-gamma release assay (IGRA) for LTBI and rapid point-of-care assays for human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infections. Independent correlates of M. tuberculosis infection were identified using multivariable log-binomial regression.

RESULTS

A total of 500 participants met the eligibility criteria. The mean age was 43.2 years (standard deviation 11.6); most subjects were White (52%) or Hispanic (30.8%), and male (75%). Overall, 86.7% reported having ever traveled to Mexico. Prevalence of M. tuberculosis infection was 23.6%; 0.8% were co-infected with HIV and 81.7% were co-infected with HCV. Almost all participants (95%) had been previously tested for M. tuberculosis; 7.6% had been previously told they were infected. M. tuberculosis infection was independently associated with being Hispanic, having longer injection histories, testing HCV-positive, and correctly reporting that people with 'sleeping' TB cannot infect others.

CONCLUSIONS

Strategies are needed to increase awareness about and treatment for M. tuberculosis infection among PWID in the US/Mexico border region.

Deportation and mental health among migrants who inject drugs along the US-Mexico border

This study describes the prevalence and factors of depressive symptoms among a sample of persons who inject drugs (PWID) with a history of deportation from the US in Tijuana, Mexico. In 2014, 132 deported PWID completed a structured questionnaire. Depressive symptoms were measured using the Center for Epidemiologic Studies Short Depression Scale (CESD-10) screening instrument. Eligible participants were ≥18 years old, injected drugs in the past month, spoke English or Spanish, and resided in Tijuana. Multivariate analyses identified factors associated with depressive symptoms. Among deported PWID, 45% reported current symptoms of depression. Deported PWID who were initially detained in the US for a crime-related reason before being deported (adjusted odds ratio (AOR): 5.27; 95% CI: 1.79-15.52) and who perceived needing help with their drug use (AOR: 2.15; 95% 1.01-4.61) had higher odds of reporting depressive symptoms. Our findings highlight the need for effective strategies targeting deported migrants who inject drugs to treat mental health and drug abuse in Tijuana. Investing in the mental health of deported PWID may also be a viable HIV prevention strategy.

Do law enforcement interactions reduce the initiation of injection drug use? An investigation in three North American settings

BACKGROUND

The prevention of drug injecting is often cited as a justification for the deployment of law enforcement and for the continuation of drug criminalization policies. We sought to characterize the impact of law enforcement interactions on the risk that people who inject drugs (PWID) report assisting others with injection initiation in three North American countries.

METHODS

Cross-sectional data from PWID participating in cohort studies in three cities (San Diego, USA; Tijuana, Mexico; Vancouver, Canada) were pooled (August 2014-December 2016). The dependent variable was defined as recently (i.e., past six months) providing injection initiation assistance; the primary independent variable was the frequency of recent law enforcement interactions, defined categorically (0 vs. 1 vs. 2-5 vs. ≥6). We employed multivariable logistic regression analyses to assess this relationship while controlling for potential confounders.

RESULTS

Among 2122 participants, 87 (4.1%) reported recently providing injection initiation assistance, and 802 (37.8%) reported recent law enforcement interactions. Reporting either one or more than five recent interactions with law enforcement was not significantly associated with injection initiation assistance. Reporting 2-5 law enforcement interactions was associated with initiation assistance (Adjusted Odds Ratio=1.74, 95% Confidence Interval: 1.01-3.02).

CONCLUSIONS

Reporting interactions with law enforcement was not associated with a reduced likelihood that PWID reported initiating others into injection drug use. Instead, we identified a positive association between reporting law enforcement interactions and injection initiation assistance among PWID in multiple settings. These findings raise concerns regarding the effectiveness of drug law enforcement to deter injection drug use initiation.

Measuring improvement in knowledge of drug policy reforms following a police education program in Tijuana, Mexico

Background

Mexico’s 2009 “narcomenudeo reform” decriminalized small amounts of drugs, shifting some drug law enforcement to the states and mandating drug treatment diversion instead of incarceration. Data from Tijuana suggested limited implementation of this harm reduction-oriented policy. We studied whether a police education program (PEP) improved officers’ drug and syringe policy knowledge, and aimed to identify participant characteristics associated with improvement of drug policy knowledge.

Methods

Pre- and post-training surveys were self-administered by municipal police officers to measure legal knowledge. Training impact was assessed through matched paired nominal data using McNemar’s tests. Multivariable logistic regression was used to identify predictors of improved legal knowledge, as measured by officers’ ability to identify conceptual legal provisions related to syringe possession and thresholds of drugs covered under the reform.

Results

Of 1750 respondents comparing pre- versus post training, officers reported significant improvement (p < 0.001) in their technical understanding of syringe possession (56 to 91%) and drug amounts decriminalized, including marijuana (9 to 52%), heroin (8 to 71%), and methamphetamine (7 to 70%). The training was associated with even greater success in improving conceptual legal knowledge for syringe possession (67 to 96%) (p < 0.001), marijuana (16 to 91%), heroin (11 to 91%), and methamphetamine (11 to 89%). In multivariable modeling, those with at least a high school education were more likely to exhibit improvement of conceptual legal knowledge of syringe possession (adjusted odds ratio [aOR] 2.6, 95% CI 1.4–3.2) and decriminalization for heroin (aOR 2.7, 95% CI 1.3–4.3), methamphetamine (aOR 2.2, 95% CI 1.4–3.2), and marijuana (aOR 2.5, 95% CI 1.6–4).

Conclusions

Drug policy reform is often necessary, but not sufficient to achieve public health goals because of gaps in translating formal laws to policing practice. To close such gaps, PEP initiatives bundling occupational safety information with relevant legal content demonstrate clear promise. Our findings underscore additional efforts needed to raise technical knowledge of the law among personnel tasked with its enforcement. Police professionalization, including minimum educational standards, appear critical for aligning policing with harm reduction goals.