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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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Design<\/jats:title>\n                    <jats:p>\n                      We employed data from three PWID cohort studies participating in\n                      <jats:italic>PReventing Injecting by Modifying Existing Responses<\/jats:italic>\n                      (PRIMER), for this cross-sectional analysis.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Setting<\/jats:title>\n                    <jats:p>Tijuana, Mexico; San Diego, USA; Vancouver, Canada.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Participants<\/jats:title>\n                    <jats:p>A total of 2944 participants were included in this study (Tijuana: n=766, San Diego: n=353, Vancouver: n=1825).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Measurements<\/jats:title>\n                    <jats:p>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.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      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 (I\n                      <jats:sup>2<\/jats:sup>\n                      : 52%), recent housing insecurity (I\n                      <jats:sup>2<\/jats:sup>\n                      : 39%) and recent non-injection heroin use (I\n                      <jats:sup>2<\/jats:sup>\n                      : 78%).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>We identified common and site-specific factors related to PWID\u2019s 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.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/bmjopen-2020-046957","type":"journal-article","created":{"date-parts":[[2021,8,12]],"date-time":"2021-08-12T12:28:27Z","timestamp":1628771307000},"page":"e046957","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":3,"title":["Involvement of people who inject drugs in injection initiation events: a cross-sectional analysis identifying similarities and differences across three North American settings"],"prefix":"10.1136","volume":"11","author":[{"given":"Charles","family":"Marks","sequence":"first","affiliation":[{"name":"Department of Medicine, University of California San Diego, La Jolla, California, USA"},{"name":"Interdisciplinary Research on Substance Use Joint Doctoral Program, San Diego State University and University of California San Diego, San Diego, California, USA"},{"name":"School of Social Work, San Diego State University, San Diego, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Stephanie A","family":"Meyers","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California San Diego, La Jolla, California, USA"},{"name":"Interdisciplinary Research on Substance Use Joint Doctoral Program, San Diego State University and University of California San Diego, San Diego, California, USA"},{"name":"School of Social Work, San Diego State University, San Diego, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Sonia","family":"Jain","sequence":"additional","affiliation":[{"name":"Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xiaoying","family":"Sun","sequence":"additional","affiliation":[{"name":"Biostatistics Research Center, Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, La Jolla, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kanna","family":"Hayashi","sequence":"additional","affiliation":[{"name":"Health Sciences, Simon Fraser University, Burnaby, British Columbia, Canada"},{"name":"British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Patricia","family":"Gonzalez-Zuniga","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California San Diego, La Jolla, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Steffanie A","family":"Strathdee","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California San Diego, La Jolla, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Richard S","family":"Garfein","sequence":"additional","affiliation":[{"name":"Family Medicine and Public Health, University of California San Diego, La Jolla, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"M J","family":"Milloy","sequence":"additional","affiliation":[{"name":"British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada"},{"name":"Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kora","family":"DeBeck","sequence":"additional","affiliation":[{"name":"British Columbia Centre on Substance Use, Vancouver, British Columbia, Canada"},{"name":"School of Public Policy, Simon Fraser University, Vancouver, British Columbia, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kevin","family":"Cummins","sequence":"additional","affiliation":[{"name":"Department of Public Health, CSU Fullerton, Fullerton, California, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0614-9386","authenticated-orcid":false,"given":"Dan","family":"Werb","sequence":"additional","affiliation":[{"name":"Department of Medicine, University of California San Diego, La Jolla, California, USA"},{"name":"Centre on Drug Policy Evaluation, Unity Health Toronto, Toronto, Ontario, Canada"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"239","published-online":{"date-parts":[[2021,8,12]]},"reference":[{"key":"2025120601112928000_11.8.e046957.1","unstructured":"United States Department of Health and Human Services . 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