Cessation of Injecting and Preceding Drug Use Patterns Among a Prospective Cohort of Street-Involved Youth

Association of current substance use treatment with future reduced methamphetamine use in an observational cohort of men who have sex with men in Los Angeles

INTRODUCTION

Methamphetamine use is highly prevalent among men who have sex with men (MSM), but knowledge of the long-term dynamics, and how they are affected by substance use treatment, is limited. This study aimed to describe trajectories of methamphetamine use among MSM, and to evaluate the impact of treatment for any kind of substance use on frequency of methamphetamine use.

METHODS

This analysis used data from a cohort of MSM in Los Angeles, CA, who participated in semi-annual study visits from 2014 to 2022. The study characterized trajectories of methamphetamine use using a continuous time multistate Markov model with three states. States were defined using self-reported frequency of methamphetamine use in the past six months: frequent (daily), occasional (weekly or less), and never. The model estimated the association between receiving treatment for any kind of substance use and changes in state of frequency of methamphetamine use.

RESULTS

This analysis included 2348 study visits among 285 individuals who were followed-up for an average of 4.4 years. Among participants who were in the frequent use state, 65 % (n = 26) of those who were receiving any kind of substance use treatment at a study visit had reduced their methamphetamine use at their next visit, compared to 33 % (n = 95) of those who were not receiving treatment. Controlling for age, race/ethnicity, and HIV-status, those who reported receiving current treatment for substance use were more likely to transition from occasional to no use (HR: 1.63, 95 % CI: 1.10-2.42) and frequent to occasional use (HR: 4.25, 95 % CI: 2.11-8.59) in comparison to those who did not report receiving current treatment for substance use.

CONCLUSIONS

Findings from this dynamic modeling study provide a new method for assessing longitudinal methamphetamine use outcomes and add important evidence outside of clinical trials that substance use treatment may reduce methamphetamine use.

Social network predictors of recent and sustained injection drug use cessation: findings from a longitudinal cohort study

BACKGROUND AND AIMS

The US opioid crisis has led to increases in overdose fatalities and the incidence of HIV, hepatitis C and other infections. This analysis examines social network predictors of recent (self-report injection followed by non-injection) and sustained (self-report non-injection at two consecutive visits among those who previously injected) injection cessation in Appalachian Kentucky.

DESIGN

Data were collected through bi-annual longitudinal assessments for Social Networks among Appalachian People (SNAP; 2008-17). Using logistic regression with generalized estimating equations that clustered on individuals, we regressed non-injection status on the number of social network members who (a) did not inject and (b) recently stopped injecting and tested for interactions between each social network exposure and prior non-injection status. Social network exposures were self-reported.

SETTING

Rural eastern Kentucky, USA.

PARTICIPANTS

Participants entered the analysis only after reporting recent injection and had to have had at least two consecutive study visits (n = 326).

MEASUREMENTS

Interviewer-administered surveys collected individual-level socio-demographics, recent (past 6 months) drug use behaviors and the names of recent social support, sex and drug-use partners.

FINDINGS

After adjusting for confounders, the number of non-injecting social network members was positively associated with recent/sustained injection cessation (adjusted odds ratio = 1.27; 95% confidence interval = 1.13-1.42) and having more social network members was associated with reduced odds of recent/sustained injection cessation. The number of previously injecting social network members who had recently stopped injecting was not statistically significantly associated with injection cessation. Neither of the interactions we tested for was statistically significant, suggesting that the relationships may be similar for those who recently stopped injecting versus had not injected for at least 1 year.

CONCLUSIONS

For each additional network member who did not inject drugs, there was an increased odds of recent and sustained injection cessation among people with a history of injection drug use in Appalachian Kentucky.

Frequent Cannabis Use Is Negatively Associated with Frequency of Injection Drug Use Among People Who Inject Drugs in a Canadian Setting

Objectives: High levels of morbidity and mortality associated with injection drug use continue to represent a significant public health challenge in many settings worldwide. Previous studies have shown an association between cannabis use and decreased risk of some drug-related harms. We sought to evaluate the association between high-intensity cannabis use and the frequency of injection drug use among people who inject drugs (PWID). Methods: The data for this analysis were collected from three prospective cohorts of PWID in Vancouver, Canada, between September 2005 and May 2018. Generalized linear mixed-effects models were used to analyze the association between daily cannabis use and the frequency of injecting illegal drugs (i.e., self-reported average number of injections per month). Results: Among the 2,619 active PWID, the frequency of injection drug use was significantly lower among people who use cannabis daily compared with people who use it less than daily (adjusted odds ratio [AOR]=0.84, 95% confidence interval [CI]: 0.73-0.95). Sub-analyses indicated that this effect was restricted to the frequency of illegal opioid injection (AOR=0.78, 95% CI: 0.68-0.90); the association between daily cannabis use and the frequency of illegal stimulant injection was not significant (AOR=1.08, 95% CI 0.93-1.25). Discussion: The findings from these prospective cohorts suggest that people who use cannabis daily were less likely to report daily injection of illegal drugs compared with people who use it less than daily. These results suggest the potential value of conducting experimental research to test whether controlled administration of cannabinoids impacts the frequency of illegal opioid injection among PWID.

Frequent Cannabis Use and Cessation of Injection of Opioids, Vancouver, Canada, 2005-2018

Objectives. To evaluate the impact of frequent cannabis use on injection cessation and injection relapse among people who inject drugs (PWID).Methods. Three prospective cohorts of PWID from Vancouver, Canada, provided the data for these analyses. We used extended Cox regression analysis with time-updated covariates to analyze the association between cannabis use and injection cessation and injection relapse.Results. Between 2005 and 2018, at-least-daily cannabis use was associated with swifter rates of injection cessation (adjusted hazard ratio [AHR] = 1.16; 95% confidence interval [CI] = 1.03, 1.30). A subanalysis revealed that this association was only significant for opioid injection cessation (AHR = 1.26; 95% CI = 1.12, 1.41). At-least-daily cannabis use was not significantly associated with injection relapse (AHR = 1.08; 95% CI = 0.95, 1.23).Conclusions. We observed that at-least-daily cannabis use was associated with a 16% increase in the hazard rate of injection cessation, and this effect was restricted to the cessation of injection opioids. This finding is encouraging given the uncertainty surrounding the impact of cannabis policies on PWID during the ongoing opioid overdose crisis in many settings in the United States and Canada.

Increasing Viral Hepatitis Knowledge Among Urban Ethnic Minority Youth: Findings from a Community Based Prevention Intervention

Viral hepatitis (VH) knowledge among youth is understudied in the United States. There has been a rise in VH cases in the U.S. in the wake of the opioid epidemic. Innovative approaches to preventing the infection are needed especially in urban communities. This study presents preliminary findings from a community-based HIV/AIDS, substance abuse, and VH prevention education intervention for ethnic minority youth in a northeastern urban community. We aimed to evaluate VH knowledge and factors associated with knowledge. Participants in the study completed a baseline survey followed by an exit survey measuring VH knowledge after the intervention. The survey was completed by 691 individuals. Logistic regression analyses were conducted and indicated that there was a significant increase (82.3%) in VH knowledge among youth who participated in the intervention. The development and implementation of VH knowledge interventions can be crucial in alleviating the rise of VH infections in the U.S.

Initiation into heroin use among street-involved youth in a Canadian setting: A longitudinal cohort study

BACKGROUND

Emerging evidence suggests that non-medical prescription opioid (NMPO) use may be a risk factor for initiating heroin use; however, pathways from PO to heroin use among youth remain underexplored. We sought to examine the association between NMPO use and heroin initiation.

METHODS

Between September 2005 and June 2017 data were derived from an open prospective cohort of street-involved youth aged 14-28 who use illegal drugs in Vancouver, Canada. The study included 526 youth who had never used non-injection heroin, and 652 youth who had never used injection heroin at baseline. We used Cox proportional hazards regressions to examine the association between NMPO use - in addition to other substance use patterns - and subsequent initiation into non-injection and injection heroin use.

RESULTS

Among those who had never used non-injection heroin at baseline, 133 (25.3%) initiated non-injection heroin use during the study period. Among those who had never injected heroin at baseline, 137 (21.0%) initiated heroin injection during the study period. In multivariable analyses, NMPO use, crack use, and crystal methamphetamine use predicted non-injection heroin initiation (all p < 0.05). In separate multivariable analyses, non-injection heroin and crystal methamphetamine predicted heroin injection initiation (all p < 0.05).

CONCLUSIONS

Among street-involved youth in this setting, NMPO use predicted initiation into non-injection heroin use but not initiation into heroin injection. Interestingly, crack cocaine and crystal methamphetamine use were stronger predictors of heroin initiation than NMPO use was, suggesting that stimulant use may carry greater risks for heroin initiation than NMPO use.

Peer influence of injection drug use cessation among dyads in rural eastern Kentucky

BACKGROUND

This analysis aims to assess whether injection drug use cessation among peers predicts injection drug use cessation among individuals and explores whether this association varies by relationship type and strength.

METHODS

Data were collected through baseline and 6-month assessments for the Social Networks among Appalachian People study (2008-2011). Interviewer-administered surveys collected sociodemographic and drug use behaviors (past 6 months and lifetime). Participants also listed sex, drug use, and social support partners (past 6 months). Listed names were cross-referenced with survey participants to identify relationships between study participants. The analytic sample was further restricted to include only those relationship pairs where both individuals reported a history of injection drug use at baseline (n = 244 unique individuals and 746 dyads). We fit a generalized estimating equations logistic regression model to (1) assess the relationship between peer injection cessation and individual injection cessation and (2) determine whether the strength of this association differs by relationship-level variables (i.e., relationship role, relationship type, relationship duration, frequency of interaction, residential proximity).

RESULTS

Overall, those with a network member who ceased injection drug use were more likely to stop injecting over the following 6-month period (AOR=1.65). The magnitude of this association was greater for social support partners (AOR=2.95), family members (AOR=3.56), those with whom the participant interacted at least daily (AOR=2.17), and those who the participant knew longer (AOR=2.09). Further, among family members, the effect size was greater when relationships were further restricted to immediate family members (AOR=5.35).

CONCLUSION

Our findings suggest that in this rural community, closer, more supportive relationships, may be more influential for modeling injection cessation; however, relationship-types were not mutually exclusive so differences in effect size across strata may not be statistically significant. In this setting, social support through the recovery process (including cessation attempts with peers) may increase likelihood of injection cessation.

Trends in Adolescent Heroin and Injection Drug Use in Nine Urban Centers in the U.S., 1999-2017

PURPOSE

Although estimates of heroin and injection drug use (IDU) among U.S. adolescents have remained low and stable, national data may mask local variation in use. Adolescent use may be higher in urban areas, many of which have historically high rates of heroin use and IDU. We investigate trends in heroin use and IDU among 9th-12th grade students in major urban centers in the U.S.

METHODS

We used local Youth Risk Behavior Survey data from all large, urban school districts (n = 9) with at least 5 years of weighted, publicly available data. We used time series mean estimation to estimate the prevalence of heroin use and IDU among high school students from 1999 to 2017 and used logistic regression to test for linear and quadratic trends.

RESULTS

We observed statistically significant linear increases in (1) lifetime heroin use in New York (β = .43, 1%-3.9%), Chicago (β = .15, 3.1%-4.6%), and Milwaukee (β = .35, 2.8%-7.4%); and (2) lifetime IDU in New York (β = .34, .8%-2.7%), Orange County (β = .17, 2.2%-3.5%), and Miami-Dade County (β = .16, 2.7%-3.9%). Only San Bernardino experienced significant decreases in heroin use (β = -.34, 4.6%-1.6%) and IDU (β = -.20, 2.5%-1.9%) over the time period.

CONCLUSIONS

In contrast to national trends, the prevalence of heroin use is increasing among adolescents in certain urban centers in the U.S. Our results illustrate that national averages mask local variation in adolescent heroin use. Further research with locally representative samples is needed to inform public health policy and practice, especially in cities where heroin problems have been historically endemic and continue to rise.

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.