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Substance use patterns and unprotected sex among street-involved youth in a Canadian setting: a prospective… Cheng, Tessa; Johnston, Caitlin; Kerr, Thomas; Nguyen, Paul; Wood, Evan; DeBeck, Kora Jan 5, 2016

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RESEARCH ARTICLE Open AccessSubstance use patterns and unprotectedsex among street-involved youth in aCanadian setting: a prospective cohortstudyTessa Cheng1,2, Caitlin Johnston1,3, Thomas Kerr1,4, Paul Nguyen1, Evan Wood1,4 and Kora DeBeck1,5*AbstractBackground: Rates of sexually transmitted infections (STI) and unplanned pregnancy are high among youth. While theintersection between drug and alcohol use and unprotected sex is well recognized, few studies have examined therelationship between substance use patterns and unprotected sex among high risk-populations such as street-involvedyouth.Methods: Data were derived from the At-Risk Youth Study (ARYS), a prospective cohort of street-involved youth fromVancouver, Canada. Generalized estimating equations (GEE) were used to examine substance use patterns that wereindependently associated with unprotected sex, defined as (vaginal or anal) sexual intercourse without consistentcondom use.Results: Between September 2005 and May 2013, 1,026 youth were recruited into the ARYS cohort and 75 % (n = 766)reported engaging in recent unprotected sex at some point during the study period. In a multivariable analysis, femalegender (adjusted odds ratio [AOR] = 1.46, 95 % confidence interval [CI]: 1.18-1.81), Caucasian ancestry (AOR = 1.38, 95 %CI: 1.13-1.68), being in a stable relationship (AOR = 4.64, 95 % CI: 3.82-5.65), having multiple sex partners (AOR = 2.60,95 % CI: 2.18-3.10) and the following substance use patterns were all independently associated with recentunprotected sex: injection or non-injection crystal methamphetamine use (AOR = 1.21, 95 % CI: 1.03-1.43), injection ornon-injection cocaine use (AOR = 1.20, 95 % CI: 1.02-1.41), marijuana use (AOR = 1.23, 95 % CI: 1.02-1.49), ecstasy use(AOR = 1.23, 95 % CI: 1.01-1.48) and alcohol use (AOR = 1.31, 95 % CI: 1.11-1.55) (all p < 0.05).Conclusions: Unprotected sex was prevalent among street-involved youth in this setting, and independentlyassociated with female gender and a wide range of substance use patterns. Evidence-based and gender-informedsexual health interventions are needed in addition to increased access to youth-centered addiction treatment services.STI testing and linkages to healthcare professionals remain important priorities for street-involved youth, and should beintegrated across all health and social services.Keywords: Street-youth, Unprotected sex, Addictions, Risk behaviour* Correspondence: uhri-kd@cfenet.ubc.ca1British Columbia Centre for Excellence in HIV/AIDS, 608-1081 Burrard Street,Vancouver, B.C., Canada, V6Z 1Y65School of Public Policy, Simon Fraser University, 515 West Hastings Street,Suite 3271, Vancouver, B.C., Canada, V6B 5K3Full list of author information is available at the end of the article© 2015 Cheng et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (, which permits unrestricted use, distribution, andreproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link tothe Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver( applies to the data made available in this article, unless otherwise stated.Cheng et al. BMC Public Health  (2016) 16:4 DOI 10.1186/s12889-015-2627-zBackgroundYouth are at a critical stage of development as they initi-ate sexual and substance use behaviours that shape theirhealth throughout adulthood [1]. The evidence suggests,however, that this crucial transition period is often over-looked and not adequately addressed by healthcare pro-viders in many settings [2]. This is especially importantfor street-involved youth, who commonly experiencetrauma and abuse before entering street life [3], and ad-verse childhood events have been linked with an in-creased risk of illicit drug use [4] and, among women,sexual risk taking [5].Despite efforts to increase safer sex practices amongyouth [6], in 2008 nearly half of all new sexually transmit-ted infections (STI) in the United States occurred amongthose aged 15–24 [7]. Although condom use amongCanadian youth has been estimated to be over 60 % since2003 [8], the rate of condom use among Canadian streetyouth is estimated to hover around 50 % [9]. The preva-lence of chlamydia and gonorrhoea has also been found tobe disproportionately higher among street-involved youth[9], with female youth generally having higher STI infec-tion rates than males [9–11]. These differences in condomuse and STI infection highlight the increased vulnerabilityof street-involved youth, and indicate that street-involvedyouth continue to experience disproportionate negativehealth outcomes and barriers to condom use.The relationship between substance use and sexual ac-tivity in the general population is well-established, asprevious studies have linked alcohol and illicit drug usewith high-risk sexual behaviours such as increased fre-quency of intercourse, multiple sexual partners, andlower rates of condom use [12–15]. Despite increasingrecognition of higher rates of STI among street-involvedyouth, less is known about substance use patterns andunprotected sex among street-involved youth who navi-gate a complex risk environment of danger on a dailybasis [16]. Given that few prospective longitudinal stud-ies have examined unprotected sex and associated drug-related risk factors among this population, the presentstudy was conducted to examine whether use of specificsubstances were associated with engaging in unprotectedsex among street-involved youth.MethodsStreet-involved youth in Vancouver, Canada were re-cruited into a prospective cohort known as the At-RiskYouth Study (ARYS), which has previously been de-scribed in detail [17]. Briefly, persons were eligible ifthey had used illicit drugs other than marijuana in thepast 30 days, were between the ages 14 and 26, providedinformed consent, and were ‘street-involved’ (defined asbeing temporarily or absolutely without housing in thepreceding six months, or having accessed street-basedyouth services during that time). Participants who wereunable to provide informed consent at the time due tointoxication, mental health issues, or inability to com-municate in English were not enrolled into our study. Atbaseline and semi-annually, participants complete aninterviewer-administered questionnaire and receive a sti-pend ($20 CDN) at each study visit. The ProvidenceHealth Care/University of British Columbia ResearchEthics Board approved the study. Based on their street-involved status, youth under the age of 19 were consid-ered emancipated minors and, consistent with provinciallaw allowing emancipated minors to consent to partici-pate in research on their own behalf, were permitted toparticipate without parental consent.This study included all participants who attended astudy visit between September 2005 and May 2013. Allparticipants were asked about their engagement in sex-ual activity over the last six months. For both same andopposite sex partnerships, participants were also askedto report how often a condom was used during vaginaland/or anal intercourse in the last six months. Possibleresponses included: always, usually, sometimes, occa-sionally, and never. In line with previous studies of con-dom use among street-involved youth [18], unprotectedsex (yes vs. no) was defined based on reports of sexualactivity and condom use. Specifically, unprotected sexwas defined as reporting any insertive or receptive sexand “inconsistent” (i.e., usually, sometimes, occasionally,or never) condom use. No unprotected sex was definedas “always” reporting condom use during sexual encoun-ters or reporting no sexual activity.Explanatory variables of interest included the followingsocio-demographic information: female gender (yes vs. no);age (≥median age vs. <median age); ethnicity (Caucasian vs.other); currently being in a stable relationship, defined asbeing legally married, or common law, or having a regularpartner (yes vs. no); and homelessness, defined as havingno fixed address, sleeping on the street, couch surfing, orstaying in a shelter or hostel (yes vs. no). Substance use var-iables included: any injection or non-injection use of crystalmethamphetamine (yes vs. no); any injection or non-injection use of powder cocaine (yes vs. no); any injectionor non-injection use of heroin (yes vs. no); any injection ornon-injection use of crack cocaine (yes vs. no); anymarijuana use (yes vs. no); any non-injection ecstasy use(yes vs. no); any alcohol use, defined as drinking beer, cider,coolers, wine, liquor, or other sources of alcohol (yes; binge drug use, defined as a period of using injectionor non-injection drugs more often than usual based on par-ticipant responses to the following question: “In the past sixmonths, did you go on runs or binges (that is, when youused non-injection drugs/injected drugs more than usual)”(yes vs. no); and any injection drug use (yes vs. no). Otherrisk characteristics included: multiple concurrent sexualCheng et al. BMC Public Health  (2016) 16:4 Page 2 of 7partners (excluding those from sex work), based on re-sponses to the following question: “In the last 6 months,how many different women/men have you had oral, vaginalor anal sex with, excluding those with whom you had sexin exchange for money or something else?” (>1 vs. ≤1); andengaging in sex work, defined as exchanging sex for money,shelter, drugs or other commodities (yes vs. no). Unlessotherwise stated, all behavioural and risk variables refer toactivities in the past six months.First, we examined baseline characteristics from par-ticipants’ first study visit, stratified by unprotected sex,using Pearson’s χ2 test. Second, we examined reports ofunprotected sex in the past six months during studyfollow-up using generalized estimating equations (GEE)with a logit link function and an exchangeable correl-ation structure for the analysis of correlated data [19].Bivariate GEE analyses were used to determine factorsassociated with unprotected sex. In order to adjust forpotential confounding in the multivariable GEE analysis,variables significant at the p < 0.10 threshold in bivariateanalyses were used in the backwards model selectionprocess. The model with the best overall fit was deter-mined by the lowest quasilikelihood under the inde-pendence model criterion (QIC) value [20]. All statisticalanalyses were performed using the SAS software version9.3 (SAS Institute, Cary, NC), and all p-values are twosided.Availability of data and materialsThe data from this study are not available in a public re-pository due to ethical concerns. Participants were assuredduring the informed consent process and throughout eachstudy visit that their responses were confidential.ResultsBetween September 2005 and May 2013, 1,026 ARYSyouths were eligible for this analysis. The median age atbaseline was 21 (inter-quartile range [IQR]: 19-23), 327(32 %) were female, and 698 (68 %) identified as Caucasian.Of this sample, 590 (58 %) youths reported engaging in un-protected sex at baseline, with an additional 176 (17 %)youths engaging in unprotected sex during follow-up. Atotal of 75 % of study participants reported unprotected sexover the study period. Participants contributed 3,605 obser-vations during the study period, which included 1,903(53 %) reports of unprotected sex. The median number ofstudy visits was 3 (IQR: 1-5). Baseline descriptive frequen-cies and bivariate analyses of characteristics of this studysample, stratified by reports of unprotected sex at baseline,are displayed in Table 1.The bivariate and multivariable GEE analyses of thesocio-demographic, drug use, and risk factors that wereassociated with unprotected sex are displayed in Table 2.In the multivariable GEE analysis, factors that werepositively and independently associated with havingunprotected sex (p < 0.05) included: female gender (ad-justed odds ratio [AOR] = 1.46, 95 % confidence interval[CI]: 1.18-1.81), Caucasian ancestry (AOR = 1.38, 95 %CI: 1.13-1.68), being in a stable relationship (AOR =4.64, 95 % CI: 3.82-5.65), any injection or non-injectioncrystal methamphetamine use (AOR = 1.21, 95 % CI:1.03-1.43), any injection or non-injection cocaine use(AOR = 1.20, 95 % CI: 1.02-1.41), any marijuana use(AOR = 1.23, 95 % CI: 1.02-1.49), any non-injection ec-stasy use (AOR = 1.23, 95 % CI: 1.01-1.48), any alcoholuse (AOR = 1.31, 95 % CI: 1.11-1.55), and having mul-tiple sex partners (AOR = 2.60, 95 % CI: 2.18-3.10).DiscussionIn the present study, 766 (75 %) youth reported recentlyengaging in unprotected sex during the study period andthe majority of study observations included a report of re-cent unprotected sex. Female gender, Caucasian ancestry,substance use, monogamous relationships, and havingmultiple concurrent sex partners, were independently andpositively associated with unprotected sex. The highprevalence of unprotected sex in this study aligns withprevious findings that up to 25 % of street-youth havenever used condoms and 56 % did not use condoms thelast time they had sex under the influence of substances[10, 21]; this contrasts with a much higher proportion ofcondom use at last intercourse among the general youthpopulation aged 20-24 in 2009/2010 (63 %) [8]. It is un-clear, however, if our study outcome of “any unprotectedsex in the recent six months” is comparable to “unpro-tected sex at last sexual intercourse”.A number of different drugs were positively and sig-nificantly associated with unprotected sex in our study.Experimentation with alcohol at an early age is commonamong young people [22], and this study found thatyouth who reported alcohol use were more likely to re-port having unprotected sex. Alcohol is known to lowerinhibitions which increases the likelihood of engaging insexual activities that one might not normally partake in,such as sexual encounters with strangers, anal inter-course, and sex without a condom [23–25].The null findings for binge drug use and injectiondrug use in the current analysis indicate that youth inour sample who engage in unprotected sex are not morelikely to engage in especially risky drug use patterns.However, crystal methamphetamine and cocaine usewere significantly associated with engaging in unpro-tected sex in our analysis. This is consistent with previ-ous research findings that stimulant drug use heightenssexual arousal and lowers inhibitions, resulting in ahigher likelihood of engaging in risky sexual behavior[26, 27]. The link between stimulant drug use, increasedsexual arousal and reduced inhibitions, resulting inCheng et al. BMC Public Health  (2016) 16:4 Page 3 of 7lower condom use, is particularly well documented inthe context of sexual health among men who have sexwith men [28]. The effect of stimulant use has also beenfound to increase risk of STI transmission among adultswho use illicit drugs, in part by facilitating longer pe-riods of sexual activity which can lead to increased riskof condom breakage [27, 29].Our results provide further evidence that reducingstimulant drug use may prevent high levels of unprotectedsex among this population. It is therefore of concern thatvulnerable youth report high rates of difficulty accessingaddiction treatment [30, 31]. Sustained efforts to improveengagement and retention in addiction treatment are war-ranted and can be expected to have positive health bene-fits beyond reductions in substance use [32, 33]. For youthwho are unable or unwilling to reduce engagement instimulant drug use, alternative interventions are needed.There is some evidence to suggest that low-thresholdTable 1 Baseline characteristicsa of street-involved youth in Vancouver stratified by unprotected sex in L6M,b 2005-2013 (n = 1,026)Characteristic Total (%) (n = 1,026) Unprotected Sex in L6Mb Odds Ratio (95 % CI)Yes (%) (n = 590) No (%) (n = 436)Female gender(yes vs. no) 327 (31.87) 213 (36.10) 114 (26.15) 1.60 (1.22-2.09)**Age(≥median vs. <median) 624 (60.82) 354 (60.00) 270 (61.93) 0.92 (0.72-1.19)Caucasian ancestry(yes vs. no) 698 (68.03) 420 (71.19) 278 (63.76) 1.40 (1.08-1.83)*Stable relationship(yes vs. no) 296 (28.85) 224 (37.97) 72 (16.51) 3.16 (2.34-4.28)***Homelessness in L6Mb(yes vs. no) 752 (73.29) 451 (76.44) 301 (69.04) 1.49 (1.12-1.97)*Any crystal meth use in L6Mb,c(yes vs. no) 461 (44.93) 276 (46.78) 185 (42.43) 1.17 (0.91-1.50)Any cocaine use in L6Mb,c(yes vs. no) 506 (49.32) 312 (52.88) 194 (44.50) 1.38 (1.07-1.77)*Any heroin use in L6Mb,c(yes vs. no) 358 (34.89) 198 (33.56) 160 (36.70) 0.87 (0.67-1.13)Any crack use in L6Mb,c(yes vs. no) 611 (59.55) 357 (60.51) 254 (58.26) 1.08 (0.84-1.40)Any marijuana use in L6Mb(yes vs. no) 903 (88.01) 516 (87.46) 387 (88.76) 0.86 (0.58-1.27)Any ecstasy use in L6Mb(yes vs. no) 334 (32.55) 211 (35.76) 123 (28.21) 1.42 (1.09-1.86)*Any alcohol use in L6Mb(yes vs. no) 833 (81.19) 499 (84.58) 334 (76.61) 1.66 (1.21-2.28)**Binge drug use in L6Mb,c(yes vs. no) 433 (42.20) 265 (44.92) 168 (38.53) 1.30 (1.01-1.67)*Injection drug use in L6Mb(yes vs. no) 306 (29.82) 173 (29.32) 133 (30.50) 0.94 (0.72-1.23)Multiple sex partners in L6Mb(>1 vs. ≤1) 558 (54.39) 371 (62.88) 187 (42.89) 2.26 (1.75-2.91)***Sex work in L6Mb(yes vs. no) 108 (10.53) 66 (11.19) 42 (9.63) 1.18 (0.79-1.78)Notes:aCharacteristics for all participants were measured from the first study visitb‘L6M’ refers to behaviours and activities occurring in the last six monthscRefers to injection or non-injection use* significant at p < 0.05; ** significant at p < 0.005; *** significant at p < 0.001Cheng et al. BMC Public Health  (2016) 16:4 Page 4 of 7services such as supervised injection facilities [34] andneedle exchange programs [35] may increase condom use;however, more studies to assess whether these secondarybenefits would be realized with street-involved youth areneeded. In addition, research indicates that the risks ofHIV transmission through sexual intercourse can be re-duced through expanded HIV testing and treatment [36].Consequently, STI and HIV testing for vulnerable youthwho use stimulants should be a public health priority andintegrated into all healthcare services.It is noteworthy that ecstasy and marijuana use were eachalso positively and significantly associated with unprotectedsex in this study. Ecstasy is known to induce feelings ofeuphoria, friendliness, and enhanced sensuality [37], andprevious research has linked ecstasy use [38, 39] andmarijuana use [40, 41] with sexual risk-taking. However,studies in this area have not been consistent and further in-vestigation into the association between ecstasy and riskysexual behavior including inconsistent condom use is war-ranted [42]. Similarly, the null findings for crack cocaineuse and inconsistent condom use in the current study con-trast with research in other settings among drug-usingyouth [43], suggesting more investigation is needed.Study findings also show that female youth are signifi-cantly more likely to engage in unprotected sex, which islinked with complex interactions of gender inequality,power, and socio-structural context [44]. Our results indi-cate that condoms are inconsistently used among parti-cipants in stable relationships and who have multipleconcurrent sex partners (38 % and 63 % at baseline, re-spectively). The positive relationship between stable rela-tionships and inconsistent condom use aligns with previousresearch [45, 46], however, the association between multipleconcurrent sex partners and inconsistent condom use isnovel. These results point to the need for tailored gender-informed interventions to support consistent condom useamong sexually active street-involved youth [47, 48].There are a number of study limitations. The absenceof a probability sample limits the ability of this study togeneralize to other settings, although our extensive re-cruitment efforts resulted in a similar sample to thosefound in other studies of Vancouver street-involvedyouth [49, 50]. Self-report surveys are also vulnerable torecall and socially-desirable response biases [51]; how-ever, under-reporting of illicit drug use and sexual prac-tices are expected to bias our results to the null.ConclusionsThis study demonstrates that unprotected sex remainshighly prevalent among drug-using youth in this settingand a number of illicit drugs were independently associ-ated with inconsistent condom use. Findings suggest thatimproving access to evidence-based and youth-centeredaddiction treatment to reduce problematic substance usecan be expected to also prevent risky sexual behaviour[52]. For those who continue to engage in substance use,better connections to healthcare services and STI testingare needed across the continuum of care. The heightenedrisk of unprotected sex among female youth in this studyalso highlights the need for gender-informed interventionsto support consistent condom use among street-involvedyouth.Table 2 Bivariate and multivariable GEE analyses of factorsassociated with unprotected sex in L6Ma (n = 1,026)Characteristic Unadjusted AdjustedOdds Ratio (95 % CI) Odds Ratio (95 % CI)Female gender(yes vs. no) 1.54 (1.25-1.90)*** 1.46 (1.18-1.81)**Age(≥median vs. <median) 0.78 (0.64-0.95)*Caucasian ancestry(yes vs. no) 1.32 (1.08-1.61)* 1.38 (1.13-1.68)**Stable relationship(yes vs. no) 3.11 (2.63-3.68)*** 4.64 (3.82-5.65)***Homelessness in L6Ma(yes vs. no) 1.16 (1.02-1.32)* 1.15 (0.99-1.33)Any crystal meth use in L6Ma,b(yes vs. no) 1.20 (1.03-1.40)* 1.21 (1.03-1.43)*Any cocaine use in L6Ma,b(yes vs. no) 1.43 (1.24-1.64)*** 1.20 (1.02-1.41)*Any heroin use in L6Ma,b(yes vs. no) 0.90 (0.77-1.05)Any crack use in L6Ma,b(yes vs. no) 1.07 (0.94-1.23)Any marijuana use in L6Ma(yes vs. no) 1.37 (1.17-1.60)*** 1.23 (1.02-1.49)*Any ecstasy use in L6Ma(yes vs. no) 1.41 (1.19-1.67)*** 1.23 (1.01-1.48)*Any alcohol use in L6Ma(yes vs. no) 1.45 (1.26-1.68)*** 1.31 (1.11-1.55)**Binge drug use in L6Ma,b(yes vs. no) 1.13 (0.99-1.30)Injection drug use in L6Ma(yes vs. no) 1.00 (0.85-1.16)Multiple sex partners in L6Ma(>1 vs. ≤ 1) 1.86 (1.60-2.17)*** 2.60 (2.18-3.10)***Sex work in L6Ma(yes vs. no) 1.19 (0.92-1.55)Notes:a‘L6M’ refers to behaviours and activities occurring in the last six monthsbRefers to injection or non-injection use*significant at p < 0.05; ** significant at p < 0.005; *** significant at p < 0.001Cheng et al. BMC Public Health  (2016) 16:4 Page 5 of 7AbbreviationsARYS: At-Risk Youth Study; AOR: Adjusted Odds Ratio; CI: Confidence Interval;GEE: Generalized Estimating Equation; IQR: Inter-Quartile Range; STI: SexuallyTransmitted Infection.Competing interestsThe author(s) declare that they have no competing interests.Author’s contributionsTC contributed to study design and the literature search, and was responsiblefor preparing the final draft of the manuscript. CJ contributed to study design,was responsible for managing the preliminary literature search, prepared theinitial draft of the manuscript, and provided critical comments on the final draftand approved the final manuscript. TK contributed to study design, and themain content of the manuscript, provided critical comments on the final draft,and approved the final manuscript. PN was responsible for conducting thestatistical analyses and contributing to the main content of the manuscript. Heprovided critical comments on the final draft, and approved the finalmanuscript. EW contributed to study design, statistical analyses, and the maincontent of the manuscript. He also provided critical comments on the finaldraft, and approved the final manuscript. KD contributed to study design,statistical analyses, and the main content of the manuscript. She also providedcritical comments on the final draft and approved the final manuscript.AcknowledgementsThe authors thank the study participants for their contribution to the research,as well as current and past researchers and staff. We would specifically like tothank Cody Callon, Deborah Graham, Peter Vann, Steve Kain, Tricia Collingham,Kristie Starr, and Carmen Rock for their research and administrative assistance.The study was supported by the US National Institutes of Health(U01DA038886) and the Canadian Institutes of Health Research (MOP–102742).This research was undertaken, in part, thanks to funding from the CanadaResearch Chairs program through a Tier 1 Canada Research Chair in Inner CityMedicine which supports Dr. Evan Wood. Dr. Kora DeBeck is supported by aMSFHR/St. Paul’s Hospital Foundation‐Providence Health Care Career ScholarAward and a CIHR New Investigator Award. Funding sources had no role instudy design; in the collection, analysis and interpretation of data; in the writingof the report; or in the decision to submit the paper for publication.Author details1British Columbia Centre for Excellence in HIV/AIDS, 608-1081 Burrard Street,Vancouver, B.C., Canada, V6Z 1Y6. 2Faculty of Health Sciences, Simon FraserUniversity, Blusson Hall, Room 11300, 8888 University Drive, Burnaby, B.C.,Canada, V5A 1S6. 3BC Women Hospital and Health Centre, 4500 Oak St,Vancouver, B.C., Canada, V6H 3V5. 4Faculty of Medicine, University of BritishColumbia, 317 - 2194 Health Sciences Mall, Vancouver, B.C., Canada, V6T 1Z3.5School of Public Policy, Simon Fraser University, 515 West Hastings Street,Suite 3271, Vancouver, B.C., Canada, V6B 5K3.Received: 25 September 2015 Accepted: 16 December 2015References1. Gilles K. Adolescence: A foundation for future health (Fact Sheet 1). In:Lancet Series on Adolescent Health Fact Sheets. Population ReferenceBureau. 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