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Rammohan I, Jain S, Sun S, Marks C, Milloy MJ, Hayashi K, DeBeck K, González-Zúñiga P, Strathdee S, Werb D. Latent polydrug use patterns and the provision of injection initiation assistance among people who inject drugs in three North American settings. Drug Alcohol Rev 2023; 42:1504-1516. [PMID: 37321850 PMCID: PMC10524861 DOI: 10.1111/dar.13687] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2022] [Revised: 03/17/2023] [Accepted: 05/05/2023] [Indexed: 06/17/2023]
Abstract
INTRODUCTION We sought to identify latent profiles of polysubstance use patterns among people who inject drugs in three distinct North American settings, and then determine whether profile membership was associated with providing injection initiation assistance to injection-naïve persons. METHODS Cross-sectional data from three linked cohorts in Vancouver, Canada; Tijuana, Mexico; and San Diego, USA were used to conduct separate latent profile analyses based on recent (i.e., past 6 months) injection and non-injection drug use frequency. We then assessed the association between polysubstance use patterns and recent injection initiation assistance provision using logistic regression analyses. RESULTS A 6-class model for Vancouver participants, a 4-class model for Tijuana participants and a 4-class model for San Diego participants were selected based on statistical indices of fit and interpretability. In all settings, at least one profile included high-frequency polysubstance use of crystal methamphetamine and heroin. In Vancouver, several profiles were associated with a greater likelihood of providing recent injection initiation assistance compared to the referent profile (low-frequency use of all drugs) in unadjusted and adjusted analyses, however, the inclusion of latent profile membership in the multivariable model did not significantly improve model fit. DISCUSSION AND CONCLUSIONS We identified commonalities and differences in polysubstance use patterns among people who inject drugs in three settings disproportionately impacted by injection drug use. Our results also suggest that other factors may be of greater priority when tailoring interventions to reduce the incidence of injection initiation. These findings can aid in efforts to identify and support specific higher-risk subpopulations of people who inject drugs.
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Affiliation(s)
- Indhu Rammohan
- Centre on Drug Policy and Evaluation, St. Michael’s Hospital, Toronto, Canada
- Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada
| | - Sonia Jain
- Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, United States
| | - Shelly Sun
- Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, United States
| | - Charles Marks
- Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, United States
- School of Community Health Sciences, University of Reno, Reno, United States
| | - M-J Milloy
- British Columbia Centre on Substance Use, Vancouver, Canada
| | - Kanna Hayashi
- British Columbia Centre on Substance Use, Vancouver, Canada
| | - Kora DeBeck
- British Columbia Centre on Substance Use, Vancouver, Canada
| | - Patricia González-Zúñiga
- Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, United States
| | - Steffanie Strathdee
- Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, United States
| | - Dan Werb
- Centre on Drug Policy and Evaluation, St. Michael’s Hospital, Toronto, Canada
- Institute of Health Policy, Management and Evaluation, University of Toronto, Toronto, Canada
- Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, United States
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Bouck Z, Tricco AC, Rosella LC, Banack HR, Fox MP, Platt RW, Milloy MJ, DeBeck K, Hayashi K, Werb D. First-line opioid agonist treatment as prevention against assisting others in initiating injection drug use: A longitudinal cohort study of people who inject drugs in Vancouver, Canada. DRUG AND ALCOHOL DEPENDENCE REPORTS 2023; 7:100168. [PMID: 37397436 PMCID: PMC10311194 DOI: 10.1016/j.dadr.2023.100168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/18/2023] [Accepted: 05/19/2023] [Indexed: 07/04/2023]
Abstract
Background Among people who inject drugs, frequent injecting and experiencing withdrawal are associated with facilitating others' first injections. As these factors may reflect an underlying substance use disorder, we investigated whether first-line oral opioid agonist treatment (OAT; methadone or buprenorphine/naloxone) reduces the likelihood that people who inject drugs help others initiate injecting. Methods We used questionnaire data from semi-annual visits between December 2014-May 2018 on 334 people who inject drugs with frequent non-medical opioid use in Vancouver, Canada. We estimated the effect of current first-line OAT on subsequent injection initiation assistance provision (i.e., helped someone initiate injecting in the following six months) using inverse-probability-weighted estimation of repeated measures marginal structural models to reduce confounding and informative censoring by time-fixed and time-varying covariates. Results By follow-up visit, 54-64% of participants reported current first-line OAT whereas 3.4-6.9% provided subsequent injection initiation assistance. Per the primary weighted estimate (n = 1114 person-visits), participants currently on first-line OAT (versus no OAT) were 50% less likely, on average, to subsequently help someone initiate injecting (relative risk [RR]=0.50, 95% CI=0.23-1.11). First-line OAT was associated with reduced risk of subsequent injection initiation assistance provision in participants who, at baseline, injected opioids less than daily (RR=0.15, 95% CI=0.05-0.44) but not in those who injected opioids daily (RR=0.86, 95% CI=0.35-2.11). Conclusions First-line OAT seemingly reduces the short-term likelihood that people who inject drugs facilitate first injections. However, the extent of this potential effect remains uncertain due to imprecise estimation and observed heterogeneity by baseline opioid injecting frequency.
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Affiliation(s)
- Zachary Bouck
- Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
- Centre on Drug Policy Evaluation, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
| | - Andrea C. Tricco
- Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
- Knowledge Translation Program, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Institute for Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada
| | - Laura C. Rosella
- Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
- ICES, Toronto, ON, Canada
| | - Hailey R. Banack
- Epidemiology Division, Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada
| | - Matthew P. Fox
- Department of Epidemiology, Boston University School of Public Health, Boston, MA, United States
- Department of Global Health, Boston University School of Public Health, Boston, MA, United States
| | - Robert W. Platt
- Department of Epidemiology, Biostatistics, and Occupational Health, McGill University, Montréal, QC, Canada
- Department of Pediatrics, McGill University, Montréal, QC, Canada
| | - M-J Milloy
- British Columbia Centre for Substance Use, Vancouver, BC, Canada
- Department of Medicine, University of British Columbia, Vancouver, BC, Canada
| | - Kora DeBeck
- British Columbia Centre for Substance Use, Vancouver, BC, Canada
| | - Kanna Hayashi
- British Columbia Centre for Substance Use, Vancouver, BC, Canada
- Faculty of Health Sciences, Simon Fraser University, Burnaby, BC, Canada
| | - Dan Werb
- Centre on Drug Policy Evaluation, St. Michael's Hospital, Unity Health Toronto, Toronto, ON, Canada
- Institute for Health Policy, Management and Evaluation, University of Toronto, Toronto, ON, Canada
- Division of Infectious Diseases and Global Public Health, University of California San Diego, La Jolla, CA, United States
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Meyers-Pantele SA, Jain S, Sun X, Marks C, DeBeck K, Hayashi K, Strathdee SA, Werb D. 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. Drug Alcohol Rev 2022; 41:686-696. [PMID: 34636100 PMCID: PMC8930605 DOI: 10.1111/dar.13390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Revised: 09/03/2021] [Accepted: 09/12/2021] [Indexed: 12/01/2022]
Abstract
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.
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Affiliation(s)
- Stephanie A. Meyers-Pantele
- Department of Psychology, San Diego State University, San Diego, USA,Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, USA
| | - Sonia Jain
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, USA
| | - Xiaoying Sun
- Department of Family Medicine and Public Health, University of California San Diego, La Jolla, USA
| | - Charles Marks
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, USA,School of Public Health, University of Nevada, Reno, USA
| | - Kora DeBeck
- British Columbia Centre on Substance Use, Vancouver, Canada
| | - Kanna Hayashi
- British Columbia Centre on Substance Use, Vancouver, Canada
| | - Steffanie A. Strathdee
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, USA
| | - Dan Werb
- Division of Infectious Diseases and Global Public Health, Department of Medicine, University of California San Diego, La Jolla, USA,Centre on Drug Policy Evaluation, St. Michael’s Hospital, Toronto, Canada
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Marks C, Meyers SA, Jain S, Sun X, Hayashi K, Gonzalez-Zuniga P, Strathdee SA, Garfein RS, Milloy MJ, DeBeck K, Cummins K, Werb D. Involvement of people who inject drugs in injection initiation events: a cross-sectional analysis identifying similarities and differences across three North American settings. BMJ Open 2021; 11:e046957. [PMID: 34385244 PMCID: PMC8362731 DOI: 10.1136/bmjopen-2020-046957] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
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.
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Affiliation(s)
- Charles Marks
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- Interdisciplinary Research on Substance Use Joint Doctoral Program, San Diego State University and University of California San Diego, San Diego, California, USA
- School of Social Work, San Diego State University, San Diego, California, USA
| | - Stephanie A Meyers
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- Interdisciplinary Research on Substance Use Joint Doctoral Program, San Diego State University and University of California San Diego, San Diego, California, USA
- School of Social Work, San Diego State University, San Diego, California, USA
| | - Sonia Jain
- Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, California, USA
| | - Xiaoying Sun
- Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, California, USA
| | - Kanna Hayashi
- Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada
- British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada
| | | | - Steffanie A Strathdee
- Department of Medicine, University of California San Diego, La Jolla, California, USA
| | - Richard S Garfein
- Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA
| | - M J Milloy
- British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada
- Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kora DeBeck
- British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada
- School of Public Policy, Simon Fraser University, Vancouver, British Columbia, Canada
| | - Kevin Cummins
- Department of Public Health, CSU Fullerton, Fullerton, California, USA
| | - Dan Werb
- Department of Medicine, University of California San Diego, La Jolla, California, USA
- Centre on Drug Policy Evaluation, Unity Health Toronto, Toronto, Ontario, Canada
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