{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,10]],"date-time":"2026-06-10T12:20:16Z","timestamp":1781094016872,"version":"3.54.1"},"reference-count":41,"publisher":"Wiley","issue":"4","license":[{"start":{"date-parts":[[2020,8,27]],"date-time":"2020-08-27T00:00:00Z","timestamp":1598486400000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":["onlinelibrary.wiley.com"],"crossmark-restriction":true},"short-container-title":["Addiction"],"published-print":{"date-parts":[[2021,4]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:sec><jats:title>Aims<\/jats:title><jats:p>To estimate the prevalence of and risk factors associated with concurrent injection of multiple substances (co\u2010injection) among a community\u2010recruited cohort of people who inject drugs.<\/jats:p><\/jats:sec><jats:sec><jats:title>Design<\/jats:title><jats:p>Cross\u2010sectional study.<\/jats:p><\/jats:sec><jats:sec><jats:title>Setting<\/jats:title><jats:p>Melbourne, Australia.<\/jats:p><\/jats:sec><jats:sec><jats:title>Participants<\/jats:title><jats:p>A sample of 720 actively injecting participants from the Melbourne Injecting Drug User Cohort Study (33% female) was extracted.<\/jats:p><\/jats:sec><jats:sec><jats:title>Measurements<\/jats:title><jats:p>We constructed two statistical models: a logistic regression model analysing correlates of co\u2010injection of any substance combination in the past month and a multinomial logistic regression model analysing correlates of three mutually exclusive groups: heroin\u2013diphenhydramine co\u2010injection only, co\u2010injection of other substances and no co\u2010injection. Risk factors examined included drug use characteristics, demographic characteristics, health service use, hepatitis C status, injection risk behaviours and previous experience of non\u2010fatal overdose.<\/jats:p><\/jats:sec><jats:sec><jats:title>Findings<\/jats:title><jats:p>One\u2010third [<jats:italic>n<\/jats:italic> = 226, 31%; 95% confidence interval (CI): 28\u201334%] of participants reported co\u2010injecting substances within the past month, with equal numbers of participants reporting injecting combinations of heroin\u2013diphenhydramine (<jats:italic>n<\/jats:italic>\u00a0=\u00a0121, 54%; 95% CI\u00a0=\u00a048\u201360%) and heroin\u2013methamphetamine (<jats:italic>n<\/jats:italic>\u00a0=\u00a0121, 54%; 95% CI\u00a0=\u00a048\u201360%). In logistic regression analyses, reporting co\u2010injection of any substance combination was associated with male sex [adjusted odds ratio (aOR)\u00a0=\u00a01.80, 95% CI\u00a0=\u00a01.18\u20132.74, <jats:italic>P<\/jats:italic>\u00a0=\u00a00.006] and injecting daily or more frequently (aOR\u00a0=\u00a02.04, 95% CI\u00a0=\u00a01.31\u20133.18, <jats:italic>P<\/jats:italic>\u00a0=\u00a00.002). In multinomial logistic regression analyses, participants reporting heroin\u2013diphenhydramine co\u2010injection only were significantly more likely to report groin injecting [adjusted relative risk ratio (aRRR)\u00a0=\u00a06.16, 95% CI\u00a0=\u00a02.80\u201313.56, <jats:italic>P<\/jats:italic>\u00a0&lt;\u00a00.001] and overdose (requiring an ambulance) in the past 12\u00a0months (aRRR\u00a0=\u00a02.81, 95% CI\u00a0=\u00a01.17\u20136.72, <jats:italic>P<\/jats:italic>\u00a0=\u00a00.021) compared with participants reporting no co\u2010injection or co\u2010injection of other substances.<\/jats:p><\/jats:sec><jats:sec><jats:title>Conclusions<\/jats:title><jats:p>A substantial proportion of people who inject drugs report co\u2010injection of multiple substances, which is associated with a range of socio\u2010demographic, drug use and health service use risk factors.<\/jats:p><\/jats:sec>","DOI":"10.1111\/add.15217","type":"journal-article","created":{"date-parts":[[2020,8,8]],"date-time":"2020-08-08T16:06:07Z","timestamp":1596902767000},"page":"876-888","update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":19,"title":["Prevalence and correlates of simultaneous, multiple substance injection (co\u2010injection) among people who inject drugs in Melbourne, Australia"],"prefix":"10.1111","volume":"116","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7418-9446","authenticated-orcid":false,"given":"Anna","family":"Palmer","sequence":"first","affiliation":[{"name":"Behaviours and Health Risks Program Burnet Institute  85 Commercial Rd Melbourne VIC 3004 Australia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5587-5379","authenticated-orcid":false,"given":"Peter","family":"Higgs","sequence":"additional","affiliation":[{"name":"Behaviours and 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