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.

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.

Female sex workers (FSWs) and female prisoners experience elevated HIV prevalence relative to the general population because of unprotected sex and unsafe drug use practices, but the antecedents of these behaviors are often structural in nature. We review the literature on HIV risk environments for FSWs and female prisoners, highlighting similarities and differences in the physical, social, economic, and policy/legal environments that need to be understood to optimize HIV prevention, treatment, and policy responses. Sex work venues, mobility, gender norms, stigma, debt, and the laws and policies governing sex work are important influences in the HIV risk environment among FSWs, affecting their exposure to violence and ability to practice safer sex and safer drug use behaviors. Female prisoners are much more likely to have a drug problem than do male prisoners and have higher HIV prevalence, yet are much less likely to have access to HIV prevention and treatment and access to drug treatment in prison. Women who trade sex or are imprisoned and engage in substance use should not be considered in separate silos because sex workers have high rates of incarceration and many female prisoners have a history of sex work. Repeated cycles of arrest, incarceration, and release can be socially and economically destabilizing for women, exacerbating their HIV risk. This dynamic interplay requires a multisectoral approach to HIV prevention and treatment that appreciates and respects that not all women are willing, able, or want to stop sex work or drug use. Women who engage in sex work, use drugs, or are imprisoned come from all communities and deserve sustained access to HIV prevention and treatment for substance use and HIV, helping them and their families to lead healthy and satisfying lives.

Female sex workers (FSWs) and female prisoners experience elevated HIV prevalence relative to the general population because of unprotected sex and unsafe drug use practices, but the antecedents of these behaviors are often structural in nature. We review the literature on HIV risk environments for FSWs and female prisoners, highlighting similarities and differences in the physical, social, economic, and policy/legal environments that need to be understood to optimize HIV prevention, treatment, and policy responses. Sex work venues, mobility, gender norms, stigma, debt, and the laws and policies governing sex work are important influences in the HIV risk environment among FSWs, affecting their exposure to violence and ability to practice safer sex and safer drug use behaviors. Female prisoners are much more likely to have a drug problem than do male prisoners and have higher HIV prevalence, yet are much less likely to have access to HIV prevention and treatment and access to drug treatment in prison. Women who trade sex or are imprisoned and engage in substance use should not be considered in separate silos because sex workers have high rates of incarceration and many female prisoners have a history of sex work. Repeated cycles of arrest, incarceration, and release can be socially and economically destabilizing for women, exacerbating their HIV risk. This dynamic interplay requires a multisectoral approach to HIV prevention and treatment that appreciates and respects that not all women are willing, able, or want to stop sex work or drug use. Women who engage in sex work, use drugs, or are imprisoned come from all communities and deserve sustained access to HIV prevention and treatment for substance use and HIV, helping them and their families to lead healthy and satisfying lives.

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.

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.

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.

We know little about predictors of injection drug cessation and relapse among female sex workers who inject drugs (FSW-PWID) at the US-Mexico border. Among HIV-negative FSW-PWID taking part in a behavioral intervention study in Tijuana and Ciudad Juárez, Cox regression was used to identify predictors of time to first cessation of injection, which was defined as reporting not having injected drugs for a period of 4 months or longer, and among that subset, we examined predictors of time to injection relapse. Among 440 women, 84 (19%) reported ceasing injection during follow-up (median time to cessation = 9.3 months); of these, 30 (35%) reported relapse to injection (median time to relapse = 3.5 months). The rate of injection cessation was lower for women reporting trading sex prior to age 18 (adj. hazard ratio (HR) = 0.64, 95% confidence interval (CI) = 0.41-1.01), ever being sexually abused (adj. HR = 0.44, 95% CI = 0.27-0.71), and a higher number of vaginal sex acts with casual clients (adj. HR = 0.99 per transaction, 95% CI = 0.98-1.00). The rate of cessation was higher for women who spent more hours on the streets on a typical day (adj. HR = 1.04/h, 95% CI = 1.01-1.08) and who lived in Tijuana vs. Ciudad Juárez (adj. HR = 2.15, 95% CI = 1.14-4.07). The rate of relapse was higher among women reporting regular drug use with clients (adj. HR = 2.17, 95% CI = 0.96-4.89) and those scoring higher on a risk injection index (adj. HR = 2.04, 95% CI = 1.15-3.61). The rate of relapse was lower for FSW-PWID with higher than average incomes (adj. HR = 0.40, 95% CI = 0.18-0.89). These findings have important implications for the scale-up of methadone maintenance treatment programs (MMTPs) in Mexico and indicate a need for gender-specific programs that address sexual abuse experiences and economic vulnerabilities faced by FSW-PWID.

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.

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.