High concordance between urine toxicology results and self-reported fentanyl use in Nevada and New Mexico.

BACKGROUND: Co-use of stimulants and opioids is often deliberate. However, the possibility remains that some people are unintentionally consuming fentanyl. To advance understanding of overdose risk, we examined the rate of concordance between self-reported fentanyl use and corresponding urine toxicology screen results. METHODS: Between August 2022-August 2023, 411 participants (adults who reported any non-medical drug use in the past three months) in Nevada and New Mexico completed a cross-sectional survey, of whom 64% (n = 270; the analytical sample) also completed a urine toxicology screen, which detects fentanyl use in the past three days. Positive predictive value, negative predictive value, sensitivity, and specificity were calculated using self-reported past three-day fentanyl use (yes/no) and urine toxicology screen results for the presence of fentanyl (positive/negative). RESULTS: Of the 270 participants who provided a urine sample, 268 are included in the descriptive statistics (two with inconclusive urine toxicology screen results were excluded). Of the 268 participants, 146 (54.5%) had a fentanyl-positive urine toxicology screen result, 122 (45.5%) had a fentanyl-negative urine toxicology screen result, 137 (51.1%) reported past three-day fentanyl use, and 130 (48.5%) reported no past three-day fentanyl use. Only 6.9% of those with a fentanyl-positive urine toxicology screen did not report recent fentanyl use. The sensitivity of self-reported fentanyl use was 93%, specificity was 97%, positive predictive value was 97%, and negative predictive value was 92%. DISCUSSION: The rate of unanticipated exposure to fentanyl (that is, positive urine screen and negative self-report) in this sample was low, at 6.9%. This runs counter to the national narrative that there is widespread unknown contamination of fentanyl in the drug supply. CONCLUSION: Future research is needed to further explore how people who use multiple substances interpret their overdose risk and what harm reduction methods they employ.

Patterns of and Rationale for the Co-use of Methamphetamine and Opioids: Findings From Qualitative Interviews in New Mexico and Nevada.

Introduction: Methamphetamine use and methamphetamine-involved deaths have increased dramatically since 2015, and opioid-related deaths now frequently involve methamphetamine. Nevada and New Mexico are states with elevated rates of opioid and methamphetamine use. In this paper, we report results from a qualitative analysis that examined patterns of methamphetamine and opioid co-use over participants' lifespan, factors that influence those patterns, and implications for health outcomes among users. Methods: Project AMPED was a multisite, mixed-methods study of methamphetamine use in Northern New Mexico and Northern Nevada. Between December 2019 and May 2020, qualitative interview participants were asked to describe their patterns of and reasons for co-administration of opioids and methamphetamine. Results: We interviewed 21 people who reported using methamphetamine in the past 3 months. Four primary patterns of methamphetamine and opioid co-use were identified: [1] using both methamphetamine and heroin, either simultaneously or sequentially (n = 12), [2] using methamphetamine along with methadone (n = 4), [3] using prescription opioids and methamphetamine (n = 1), and [4] using only methamphetamine (n = 4). Among those who used methamphetamine and heroin simultaneously or sequentially, motivations drew from a desire to enhance the effect of one drug or another, to feel the "up and down" of the "perfect ratio" of a goofball, or to mitigate unwanted effects of one or the other. Among those who used methamphetamine and methadone, motivations focused on alleviating the sedative effects of methadone. Conclusion: To address the emergent trend of increasing methamphetamine-related deaths, researchers, health care professionals, and community health workers must acknowledge the decision-making processes behind co-use of opioids and methamphetamine, including the perceived benefits and harms of co-use. There is an urgent need to address underlying issues associated with drug use-related harms, and to design interventions and models of treatment that holistically address participants' concerns.

A mixed methods study of the social support networks of female sex workers and their primary noncommercial male partners in Tijuana, Mexico.

Female sex workers (FSWs) are at risk for multiple health harms, including HIV. This article describes a mixed methods study of the social support networks of 19 FSWs and their primary male sex partners in Tijuana, Mexico. We collected quantitative and qualitative social network data, including quantitative network measures, qualitative narratives, and network visualizations. Methodologically, we illustrate how a convergent mixed methods approach to studying personal social support networks of female sex workers can yield a more holistic understanding of network composition and role. From a health-related perspective, we show how migration/deportation and stigma shape social networks and might be leveraged to support HIV prevention interventions. We believe others can benefit from a mixed methods approach to studying social networks.

Impact of Public Safety Policies on Human Immunodeficiency Virus Transmission Dynamics in Tijuana, Mexico.

Background: North Tijuana, Mexico is home to many individuals at high risk for transmitting and acquiring human immunodeficiency virus (HIV). Recently, policy shifts by local government impacted how these individuals were handled by authorities. Here we examined how this affected regional HIV transmission dynamics. Methods: HIV pol sequences and associated demographic information were collected from 8 research studies enrolling persons in Tijuana and were used to infer viral transmission patterns. To evaluate the impact of recent policy changes on HIV transmission dynamics, qualitative interviews were performed on a subset of recently infected individuals. Results: Between 2004 and 2016, 288 unique HIV pol sequences were obtained from individuals in Tijuana, including 46.4% from men who have sex with men, 42.1% from individuals reporting transactional sex, and 27.8% from persons who inject drugs (some individuals had >1 risk factor). Forty-two percent of sequences linked to at least 1 other sequence, forming 37 transmission clusters. Thirty-two individuals seroconverted during the observation period, including 8 between April and July 2016. Three of these individuals were putatively linked together. Qualitative interviews suggested changes in policing led individuals to shift locations of residence and injection drug use, leading to increased risk taking (eg, sharing needles). Conclusions: Near real-time molecular epidemiologic analyses identified a cluster of linked transmissions temporally associated with policy shifts. Interviews suggested these shifts may have led to increased risk taking among individuals at high risk for HIV acquisition. With all public policy shifts, downstream impacts need to be carefully considered, as even well-intentioned policies can have major public health consequences.

Cross-border injection drug use and HIV and hepatitis C virus seropositivity among people who inject drugs in San Diego, California.

BACKGROUND: The prevalence of HIV and Hepatitis C Virus (HCV) are significantly lower among people who inject drugs (PWID) in San Diego, CA, USA compared with PWID in Tijuana, Mexico, located directly across the border. We investigated associations between cross-border injection drug use (IDU), HIV and HCV seroprevalence and engagement in injecting risk behaviours while on each side of the border. METHODS: Using baseline interviews and serologic testing data from STAHR II, a longitudinal cohort study of PWID in San Diego, bivariate and multivariable logistic regression analyses examined associations between recent (past six months) cross-border IDU and HIV and HCV antibody seropositivity, socio-demographics, drug use characteristics, and participants' connections to, and perceptions about Mexico. Chi-squared tests and McNemar tests examined associations between cross-border IDU and injecting risk behaviours. RESULTS: Of the 567 participants (93% U.S.-born, 73% male, median age 45 years), 86 (15%) reported recent cross-border IDU. Cross-border IDU was not associated with HIV (OR: 0.85, 95% CI: 0.37-1.95) or HCV seropositivity (OR: 1.01, 95% CI: 0.62-1.65). Age, identifying as Hispanic or Latino/a, and being concerned about risk of violence when travelling to Mexico were independently associated with decreased odds of recent cross-border IDU. Injecting cocaine at least weekly, having ever lived in Mexico and knowing PWID who reside in Mexico were associated with increased odds of recent cross-border IDU. PWID who reported cross-border IDU were significantly less likely to engage in receptive needle sharing, equipment sharing, and public injection while in Mexico compared with in San Diego (all p<0.001). CONCLUSION: Prevalence of HIV and HCV infection was similar among PWID who had and had not injected in Mexico, possibly due to practising safer injecting while in Mexico. Research is needed to elucidate contextual factors enabling U.S. PWID to inject safely while in Mexico.

Differential experiences of Mexican policing by people who inject drugs residing in Tijuana and San Diego.

BACKGROUND: Research among people who inject drugs (PWIDs) in the USA and Mexico has identified a range of adverse health impacts associated with policing of PWIDs. We employed a mixed methods design to investigate how PWIDs from San Diego and Mexico experienced policing in Tijuana, and how these interactions affect PWIDs behavior, stratifying by country of origin. METHODS: In 2012-2014, 575 PWIDs in San Diego, 102 of whom had used drugs in Mexico in the past six months, were enrolled in the STAHR-II study, with qualitative interviews conducted with a subsample of 20 who had recently injected drugs in Mexico. During this period, 735 PWIDs in Tijuana were also enrolled in the El Cuete-IV study, with qualitative interviews conducted with a subsample of 20 recently stopped by police. We calculated descriptive statistics for quantitative variables and conducted thematic analysis of qualitative transcripts. Integration of these data involved comparing frequencies across cohorts and using qualitative themes to explain and explore findings. RESULTS: Sixty-one percent of San Diego-based participants had been recently stopped by law enforcement officers (LEOs) in Mexico; 53% reported it was somewhat or very likely that they would be arrested while in Mexico because they look like a drug user. Ninety percent of Tijuana-based participants had been recently stopped by LEOs; 84% reported it was somewhat or very likely they could get arrested because they look like a drug user. Participants in both cohorts described bribery and targeting by LEOs in Mexico. However, most San Diego-based participants described compliance with bribery as a safeguard against arrest and detention, with mistreatment being rare. Tijuana-based participants described being routinely targeted by LEOs, were frequently detained, and reported instances of sexual and physical violence. Tijuana-based participants described modifying how, where, and with whom they injected drugs in response; and experienced feelings of stress, anxiety, and powerlessness. This was less common among San Diego-based participants, who mostly attempted to avoid contact with LEOs in Mexico while engaging in risky injection behavior. CONCLUSION: Experiences of discrimination and stigma were reported by a larger proportion of PWIDs living in Mexico, suggesting that they may be subject to greater health harms related to policing practices compared with those residing in the USA. Our findings reinforce the importance of efforts to curb abuse and align policing practices with public health goals in both the US and Mexico.

HIV Transmission Networks in the San Diego-Tijuana Border Region.

BACKGROUND: HIV sequence data can be used to reconstruct local transmission networks. Along international borders, like the San Diego-Tijuana region, understanding the dynamics of HIV transmission across reported risks, racial/ethnic groups, and geography can help direct effective prevention efforts on both sides of the border. METHODS: We gathered sociodemographic, geographic, clinical, and viral sequence data from HIV infected individuals participating in ten studies in the San Diego-Tijuana border region. Phylogenetic and network analysis was performed to infer putative relationships between HIV sequences. Correlates of identified clusters were evaluated and spatiotemporal relationships were explored using Bayesian phylogeographic analysis. FINDINGS: After quality filtering, 843 HIV sequences with associated demographic data and 263 background sequences from the region were analyzed, and 138 clusters were inferred (2-23 individuals). Overall, the rate of clustering did not differ by ethnicity, residence, or sex, but bisexuals were less likely to cluster than heterosexuals or men who have sex with men (p = 0.043), and individuals identifying as white (p ≤ 0.01) were more likely to cluster than other races. Clustering individuals were also 3.5 years younger than non-clustering individuals (p < 0.001). Although the sampled San Diego and Tijuana epidemics were phylogenetically compartmentalized, five clusters contained individuals residing on both sides of the border. INTERPRETATION: This study sampled ~ 7% of HIV infected individuals in the border region, and although the sampled networks on each side of the border were largely separate, there was evidence of persistent bidirectional cross-border transmissions that linked risk groups, thus highlighting the importance of the border region as a "melting pot" of risk groups. FUNDING: NIH, VA, and Pendleton Foundation.

Prevalence and correlates of neck injection among people who inject drugs in Tijuana, Mexico.

INTRODUCTION AND AIMS: Injecting drugs in the neck has been related to adverse health conditions such as jugular vein thrombosis, deep neck infections, aneurysm, haematomas, airway obstruction, vocal cord paralysis and wound botulism, among others. We identified prevalence and correlates of neck injection among people who inject drugs (PWID) in Tijuana, Mexico. DESIGN AND METHODS: Beginning in 2011, PWID aged ≥18 years who injected drugs within the last month were recruited into a prospective cohort. At baseline and semi-annually, PWID completed interviewer-administered surveys soliciting data on drug-injecting practices. Logistic regression was used to identify predictors of injecting in the neck as the most frequent injection site at a single visit. RESULTS: Of 380 PWID, 35.3% injected in the neck at least once in the past 6 months, among whom 71.6% reported it as their most common injection site, the most common injecting site after the arms (47%). Controlling for age, years injecting and injecting frequency, injecting heroin and methamphetamine two or more times per day and having sought injection assistance were associated with injecting in the neck [adjusted odds ratios (AOR): 2.12; 95% confidence intervals (CI): 1.27-3.53 and AOR: 2.65; 95% CI: 1.52-4.53 respectively]. DISCUSSION AND CONCLUSIONS: Injecting in the neck was very common among PWID in Tijuana and was associated with polydrug use and seeking injection assistance. Tailoring harm reduction education interventions for individuals who provide injection assistance ('hit doctors') may allow for the dissemination of safe injecting knowledge to reduce injection-related morbidity and mortality.

Place of Residence Moderates the Relationship Between Emotional Closeness and Syringe Sharing Among Injection Drug Using Clients of Sex Workers in the US-Mexico Border Region.

Injection drug-using men from the US and Mexico who purchase sex in Tijuana, Mexico are at risk for transmitting HIV to their contacts in both countries via syringe sharing. We used social network methods to understand whether place of residence (US vs. Mexico) moderated the effect of emotional closeness on syringe sharing. We interviewed 199 drug-using men who reported paying/trading for sex in Tijuana, Mexico using an epidemiological and social network survey and collected samples for HIV/STI testing. Seventy-two men reported using injection drugs with 272 network contacts. Emotional closeness was strongly associated with syringe sharing in relationship where the partner lives in the US, while the relationship between emotional closeness and syringe sharing was considerably less strong in dyads where the partner lives in Mexico. Efforts to reduce HIV risk behaviors in emotionally close relationships are needed, and could benefit from tailoring to the environmental context of the relationship.

Perceived stigma of purchasing sex among Latino and non-Latino male clients of female sex workers in Tijuana, Mexico.

HIV prevention efforts must be comprehensive in their understanding of the factors involved in HIV risk. Male clients, who have received less research attention than female sex workers (FSWs), may experience stigma as a function of purchasing sex. Perceived stigma may be related to poor psychological outcomes, risky psychosexual characteristics, and higher drug and sexual risk behavior among male clients of FSWs. However, perceived stigma of purchasing sex may differ between clients of different ethnic groups. In the present study, we examine the correlates of perceived stigma of purchasing sex among Latino versus non-Latino male clients of FSWs in Tijuana, Mexico. Using time-location sampling, we recruited 375 male clients (323 Latino, 52 non-Latino) in Tijuana who completed a computerized survey on various measures. We measured perceived stigma of purchasing sex using three items we developed for this study. Using linear regression analyses we found that perceived stigma was associated with greater guilt, a greater feeling of escape from everyday life, and more negative condom attitudes among Latino clients. This was not found among non-Latino clients. Features of Latino culture, like machismo, and how they may relate to stigma of purchasing sex are discussed.

Hazardous drinking and HIV-risk-related behavior among male clients of female sex workers in Tijuana, Mexico.

BACKGROUND AND OBJECTIVES: Male clients of female sex workers (FSWs) are at high risk for HIV. Whereas the HIV risks of alcohol use are well understood, less is known about hazardous alcohol use among male clients of FSWs, particularly in Mexico. We sought to identify risk factors for hazardous alcohol use and test associations between hazardous alcohol use and HIV risk behavior among male clients in Tijuana. METHOD: Male clients of FSWs in Tijuana (n = 400) completed a quantitative interview in 2008. The AUDIT was used to characterize hazardous alcohol use. Multivariate logistic regression was used to determine independent associations of demographic and HIV risk variables with hazardous alcohol use (vs. non-hazardous). RESULTS: Forty percent of our sample met criteria for hazardous alcohol use. Variables independently associated with hazardous drinking were reporting any sexually transmitted infection (STI), having sex with a FSW while under the influence of alcohol, being younger than 36 years of age, living in Tijuana, and ever having been jailed. Hazardous drinkers were less likely ever to have been deported or to have shared injection drugs. DISCUSSION AND CONCLUSIONS: Hazardous alcohol use is associated with HIV risk, including engaging in sex with FSWs while intoxicated and having an STI among male clients of FSWs in Tijuana. SCIENTIFIC SIGNIFICANCE: We systematically described patterns and correlates of hazardous alcohol use among male clients of FSWs in Tijuana, Mexico. The results suggest that HIV/STI risk reduction interventions must target hazardous alcohol users, and be tailored to address alcohol use.

Rethinking risk: gender and injection drug-related HIV risk among female sex workers and their non-commercial partners along the Mexico-U.S. border.

BACKGROUND: Studies of injection drug-using couples suggest a gendered performance of risk in which men exert greater control over drug use and render their female partners vulnerable to HIV infection and other negative health outcomes. This study assesses gender roles in injection drug use as practiced among female sex workers and their intimate male partners within a risk environment marked by rapid socioeconomic changes. METHODS: We draw on quantitative surveys, semi-structured interviews, and ethnographic fieldwork conducted as part of cohort study of HIV/STI risk among female sex workers and their intimate, non-commercial partners along the Mexico-U.S. border. This study employed descriptive statistics and inductive analyses of transcripts and field notes to examine practices related to drug procurement, syringe sharing, and injection assistance among couples in which both partners reported injecting drugs in the past 6 months. RESULTS: Among 156 couples in which both partners injected drugs (n=312), our analyses revealed that women's roles in drug use were active and multidimensional, and both partners' injection risk practices represented embodied forms of cooperation and compassion. Women often earned money to purchase drugs and procured drugs to protect their partners from the police. Sharing drugs and syringes and seeking injection assistance were common among couples due to drug market characteristics (e.g., the use of "black tar" heroin that clogs syringes and damages veins). Both women and men provided and received injection assistance, which was typically framed as caring for the partner in need of help. CONCLUSION: Our mixed methods study suggests that in certain risk environments, women are more active participants in injection-related practices than has often been revealed. This participation is shaped by dynamic relationship and structural factors. Our suggestion to consider gendered injection risk as a nuanced and relational process has direct implications for future research and interventions.

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.

BACKGROUND: Policymakers and researchers seek answers to how liberalized drug policies affect people who inject drugs (PWID). In response to concerns about the failing "war on drugs," Mexico recently implemented drug policy reforms that partially decriminalized possession of small amounts of drugs for personal use while promoting drug treatment. Recognizing important epidemiologic, policy, and socioeconomic differences between the United States-where possession of any psychoactive drugs without a prescription remains illegal-and Mexico-where possession of small quantities for personal use was partially decriminalized, we sought to assess changes over time in knowledge, attitudes, behaviors, and infectious disease profiles among PWID in the adjacent border cities of San Diego, CA, USA, and Tijuana, Baja California, Mexico. METHODS: Based on extensive binational experience and collaboration, from 2012-2014 we initiated two parallel, prospective, mixed methods studies: Proyecto El Cuete IV in Tijuana (n = 785) and the STAHR II Study in San Diego (n = 575). Methods for sampling, recruitment, and data collection were designed to be compatible in both studies. All participants completed quantitative behavioral and geographic assessments and serological testing (HIV in both studies; hepatitis C virus and tuberculosis in STAHR II) at baseline and four semi-annual follow-up visits. Between follow-up assessment visits, subsets of participants completed qualitative interviews to explore contextual factors relating to study aims and other emergent phenomena. Planned analyses include descriptive and inferential statistics for quantitative data, content analysis and other mixed-methods approaches for qualitative data, and phylogenetic analysis of HIV-positive samples to understand cross-border transmission dynamics. RESULTS: Investigators and research staff shared preliminary findings across studies to provide feedback on instruments and insights regarding local phenomena. As a result, recruitment and data collection procedures have been implemented successfully, demonstrating the importance of binational collaboration in evaluating the impact of structural-level drug policy reforms on the behaviors, health, and wellbeing of PWID across an international border. CONCLUSIONS: Our prospective, mixed methods approach allows each study to be responsive to emerging phenomena within local contexts while regular collaboration promotes sharing insights across studies. The strengths and limitations of this approach may serve as a guide for other evaluations of harm reduction policies internationally.

Correlates of self-efficacy for condom use among male clients of female sex workers in Tijuana, Mexico.

Male clients of female sex workers (FSWs) in Tijuana, Mexico engage in high levels of unprotected sex. While behavioral change theories posit that self-efficacy predicts condom use, correlates of self-efficacy for condom use remain largely unstudied. We examined these correlates among male clients of FSWs in Tijuana. Eligible male clients were at least 18 years of age, HIV-negative, lived in Tijuana or San Diego, reported unprotected sex with a Tijuana FSW at least once in the past 4 months, and agreed to be treated for sexually transmitted infections (STIs). Participants completed an interviewer-administered questionnaire including demographics, substance use, psychosocial and psychosexual characteristics (e.g., outcome expectancies for negotiation of safer sex, social support, and sexual sensation seeking), and sexual behaviors. Participants also underwent HIV/STI testing. A stepwise hierarchical multiple regression analysis identified correlates of self-efficacy for condom use. Of 393 male clients, median age was 37 years. Participants were mostly Spanish-speaking and employed. Factors independently associated with higher self-efficacy for condom use were higher positive outcome expectancies for negotiation of safer sex, lower sexual sensation seeking scores, and higher social support scores. Both psychosocial and psychosexual factors may influence self-efficacy for condom use among male clients of FSWs. These factors represent central constructs in sociocognitive models that explain behavioral change and could be intervention targets for improving self-efficacy for condom use and, ultimately, safer sex behavior.

Drug-using male clients of female sex workers who report being paid for sex: HIV/sexually transmitted infection, demographic, and drug use correlates.

BACKGROUND: Research has focused on male clients of female sex workers (FSWs) and their risk for HIV/sexually transmitted infections (STIs). However, it is unclear whether the commercial sex behaviors of these men are limited to paying for sex or whether they may also be paid for sex themselves. METHODS: We analyzed the interview data and HIV/STI test results from 170 drug-using male clients of FSWs in Tijuana, Mexico, to determine the extent to which these men report being paid for sex and the association with positive HIV/STI results. RESULTS: More than one quarter of men reported having been paid for sex in the past 4 months. In a multivariate logistic regression model, reporting having been paid for sex was significantly associated with testing positive for any HIV/STI (adjusted odds ratio [AdjOR], 3.53; 95% confidence interval [CI], 1.33-9.35), being bisexual (AdjOR, 15.59; 95% CI, 4.81-50.53), injection drug use in the past 4 months (AdjOR, 2.65; 95% CI, 1.16-6.03), and cocaine use in the past 4 months (AdjOR, 2.93; 95% CI, 1.22-7.01). CONCLUSIONS: Findings suggest that drug-using male clients of FSWs may be characterized by unique risk profiles that require tailored HIV prevention interventions.

Context matters: the moderating role of bar context in the association between substance use during sex and condom use among male clients of female sex workers in Tijuana, Mexico.

Tijuana is situated on Mexico's northern border with the U.S., where sex work is quasi-legal. Whereas previous work has focused on the risk behaviors of female sex workers (FSWs), less is known about the risk behaviors of their male clients. Further, research has not examined structural factors as moderators of the association between substance use and condom use, including the contexts in which sex takes place. The purpose of the current study is to examine whether having sex with FSWs in a bar moderates the link between alcohol intoxication during sex and condom use. We recruited 375 male clients of FSWs in Tijuana, Mexico from San Diego, California and Tijuana. Using computer assisted interviewing, we surveyed participants on their alcohol use, condom use, and physical contexts of sex with FSWs in the past 4 months. Results showed that more frequent intoxication during sex with FSWs is associated with more unprotected sex, but only among clients having sex with FSWs in a bar context. Results point to potential reasons for inconsistent condom use with FSWs in this context, including lower risk perceptions of sex with FSWs in bars. Future research should examine structural factors that underlie clients' risk behavior in bars in order to inform structural-level HIV prevention interventions.

Factors associated with pathways toward concurrent sex work and injection drug use among female sex workers who inject drugs in northern Mexico.

AIMS: To identify factors associated with time to initiation of (i) sex work prior to injecting drugs initiation; (ii) injection drug use prior to sex work initiation; and (iii) concurrent sex work and injection drug use (i.e. initiated at the same age) among female sex workers who currently inject drugs (FSW-IDU). DESIGN: Parametric survival analysis of baseline data for time to initiation event. SETTING: Tijuana and Ciudad Juarez situated on the Mexico-US border. PARTICIPANTS: A total of 557 FSW-IDUs aged ≥18 years. MEASUREMENTS: Interview-administered surveys assessing context of sex work and injection drug use initiation. FINDINGS: Nearly half (n = 258) initiated sex work prior to beginning to inject, a third (n = 163) initiated injection first and a quarter (n = 136) initiated both sex work and injection drug use concurrently. Low education and living in Ciudad Juarez accelerated time to sex work initiation. Being from a southern Mexican state and initiating drug use with inhalants delayed the time to first injection drug use. Having an intimate partner encourage entry into sex work and first injecting drugs to deal with depression accelerated time to initiating sex work and injection concurrently. Early physical abuse accelerated time to initiating sex work and injection, and substantially accelerated time to initiation of both behaviors concurrently. CONCLUSIONS: Among female sex workers who currently inject drugs in two Mexican-US border cities, nearly half appear to initiate sex work prior to beginning to inject, nearly one-third initiate injection drug use before beginning sex work and one-quarter initiate both behaviors concurrently. Predictors of these three trajectories differ, and this provides possible modifiable targets for prevention.

The social and environmental context of cross-border drug use in Mexico: findings from a mixed methods study of young injection drug users living in San Diego, CA.

The authors report the results of qualitative (n = 19) and quantitative (n = 545) interviews with young injection drug users (IDUs) in San Diego, California about their experiences using drugs in Tijuana, Mexico, and associated risks for HIV infection. Young IDUs who have ever traveled to Mexico (n = 365) used a variety of injection (54%) and noninjection (30%) drugs there and appear to be heavier users than those who have never traveled to Mexico. Sociocultural themes influencing drug use in Mexico included interactions among the purpose of travel, drug preference, and route of administration; familiarity with the border region; evolving relationships with the United States and Mexican drug markets; and the experience of crossing the U.S.-Mexico border. Interventions for IDUs in border regions need to be sensitive to the ethnicity, familiarity with the border region, and life history of participants, as well as differences in national policies that could influence drug use and risk for HIV on both sides of the border.

Reconciling incongruous qualitative and quantitative findings in mixed methods research: exemplars from research with drug using populations.

Mixed methods research is increasingly being promoted in the health sciences as a way to gain more comprehensive understandings of how social processes and individual behaviours shape human health. Mixed methods research most commonly combines qualitative and quantitative data collection and analysis strategies. Often, integrating findings from multiple methods is assumed to confirm or validate the findings from one method with the findings from another, seeking convergence or agreement between methods. Cases in which findings from different methods are congruous are generally thought of as ideal, whilst conflicting findings may, at first glance, appear problematic. However, the latter situation provides the opportunity for a process through which apparently discordant results are reconciled, potentially leading to new emergent understandings of complex social phenomena. This paper presents three case studies drawn from the authors' research on HIV risk amongst injection drug users in which mixed methods studies yielded apparently discrepant results. We use these case studies (involving injection drug users [IDUs] using a Needle/Syringe Exchange Program in Los Angeles, CA, USA; IDUs seeking to purchase needle/syringes at pharmacies in Tijuana, Mexico; and young street-based IDUs in San Francisco, CA, USA) to identify challenges associated with integrating findings from mixed methods projects, summarize lessons learned, and make recommendations for how to more successfully anticipate and manage the integration of findings. Despite the challenges inherent in reconciling apparently conflicting findings from qualitative and quantitative approaches, in keeping with others who have argued in favour of integrating mixed methods findings, we contend that such an undertaking has the potential to yield benefits that emerge only through the struggle to reconcile discrepant results and may provide a sum that is greater than the individual qualitative and quantitative parts.

Border crossing to inject drugs in Mexico among injection drug users in San Diego, California.

We examined correlates of ever injecting drugs in Mexico among residents of San Diego, California. From 2007 to 2010, injecting drug users (IDUs) in San Diego underwent an interviewer-administered survey. Logistic regression identified correlates of injection drug use in Mexico. Of 302 IDUs, 38% were Hispanic, 72% male and median age was 37; 27% ever injected in Mexico; 43% reported distributive syringe sharing there. Factors independently associated with ever injecting drugs in Mexico included being younger at first injection, injecting heroin, distributive syringe sharing at least half of the time, and transporting drugs over the last 6 months. One-quarter of IDUs reported ever injecting drugs in Mexico, among whom syringe sharing was common, suggesting possible mixing between IDUs in the Mexico-US border region. Prospective studies should monitor trends in cross-border drug use in light of recent Mexican drug policy reforms partially decriminalizing drug possession.