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Declining trends in the rates of assisted injecting: a prospective cohort study Pedersen, Jeanette S; Dong, Huiru; Small, Will; Wood, Evan; Nguyen, Paul; Kerr, Thomas; Hayashi, Kanna Jan 27, 2016

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RESEARCH Open AccessDeclining trends in the rates of assistedinjecting: a prospective cohort studyJeanette Somlak Pedersen1, Huiru Dong2, Will Small2,3, Evan Wood2,4, Paul Nguyen2, Thomas Kerr2,4and Kanna Hayashi2,4,5*AbstractBackground: Assisted injecting has been associated with increased risk of blood-borne infections, overdose, andother harms among people who inject drugs (PWID), particularly women. Given the changing availability of relevantharm reduction interventions in Vancouver, Canada, in recent years, we conducted a gender-based analysis toexamine changes in rates and correlates of assisted injecting over time among active PWID.Methods: Using data from a prospective cohort of PWID in Vancouver, we employed gender-stratified multivariablegeneralized estimating equations to examine trends in assisted injecting and identify the correlates during twoperiods: June 2006–November 2009 and December 2009–May 2014.Results: Among 1119 participants, 376 (33.6 %) were females. Rates of assisted injecting declined between 2006and 2014 among males (21.9 to 13.8 %) and females (37.0 to 25.6 %). In multivariable analyses, calendar year ofinterview also remained independently and negatively associated with assisted injecting among males (adjustedodds ratio [AOR] 0.95, 95 % confidence interval [CI] 0.92–0.99) and females (AOR 0.93, 95 % CI 0.89–0.97). Syringeborrowing remained independently associated with assisted injecting throughout the study period among females(AOR 1.53, 95 % CI 1.10–2.11 during 2006–2009; AOR 2.15, 95 % CI 1.24–3.74 during 2009–2014) and during2009–2014 among males (AOR 1.88, 95 % CI 1.02–3.48).Conclusions: Our findings demonstrate assisted injecting has significantly decreased for both males andfemales over the past decade. Nevertheless, rates of assisted injecting remain high, especially among women,and are associated with high-risk behavior, indicating a need to provide safer assisted injecting services tothese vulnerable sub-populations of PWID.Keywords: Assisted injecting, Injection drug use, Harm reduction, VancouverBackgroundInjection drug use is a major public health issue associ-ated with significant health and social consequences.People who require assistance injecting have been shownto be a particularly vulnerable subgroup of people whoinject drugs (PWID) [1, 2]. Assisted injection, which re-fers to manual administration of an injection to anotherperson [3], is common among PWID, with a 1996–2002study estimating that 41 % of PWID in a large Canadiancity reported assisted injecting within the previous6 months [1].Assisted injecting is a major risk factor for many nega-tive health outcomes. As those who provide assistanceinjecting often use the same syringe between two indi-viduals, there is an independent association betweenrequiring help injecting and syringe sharing—a well-established risk behavior for blood-borne infections [4,5]. Research has documented that assisted injecting isstrongly associated with HIV [1, 6, 7], hepatitis C [8],and cutaneous injection-related infections [9]. OneCanadian study found a twofold higher risk of HIV in-fection among those requiring assistance injecting [1].The negative health consequences of assisted injectingare not only limited to infections but also include non-* Correspondence: khayashi@cfenet.ubc.ca2British Columbia Centre for Excellence in HIV/AIDS, St. Paul’s Hospital,608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, Canada4Department of Medicine, University of British Columbia, St. Paul’s Hospital,608-1081 Burrard Street, Vancouver, BC V6Z 1Y6, CanadaFull list of author information is available at the end of the article© 2016 Pedersen et al. Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0International License (http://creativecommons.org/licenses/by/4.0/), 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(http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.Pedersen et al. Harm Reduction Journal  (2016) 13:2 DOI 10.1186/s12954-016-0092-3fatal overdoses [10] and vulnerability to various forms ofviolence (e.g., robbery) [11].Previous research has indicated that female PWIDmay be more likely than males to require assistance withinjecting [1, 2, 4, 12]. The higher rates of assisted inject-ing among females may be due to social and interper-sonal dynamics where males often control the use ofdrugs within relationships [1, 6, 11, 13, 14]. Conse-quently, females are commonly injected by males [11],and in turn, many women report requiring assistancewith injecting due to a lack of knowledge on how to in-ject themselves [2]. Although the reasons for needing as-sistance with injecting may be highly gendered, commonreasons for assisted injecting include a lack of viableveins, reliance upon jugular injection, being in with-drawal, and a lack of knowledge of how to inject [2, 4].In Vancouver, Canada, some harm reduction strategieshave been implemented over the past decade to addressthe harms associated with assisted injecting. In Septem-ber 2003, a medically supervised injection facility (SIF)opened in the city’s Downtown Eastside neighborhood,an area with high levels of injection drug use and HIVinfection [15]. There, healthcare staff provides educationon safer injection techniques [16]; however, the lawsgoverning the SIF do not allow healthcare staff and peersto perform manual assistance with injecting, constitutinga significant barrier for some PWID who are unable toself-inject [11]. In response, in 2005, the Vancouver AreaNetwork of Drug Users (VANDU), a local drug userorganization, began operating the Injection SupportTeam (IST) whereby trained peer volunteers walked thestreets of the Downtown Eastside providing education,support, and assistance with injections [3]. However, itceased operating in 2009 due to a lack of funding. Sub-sequently, between 2011 and 2013, a peer-run unsanc-tioned SIF was operated by VANDU in the DowntownEastside, where trained peer volunteers provided assistedinjections under a strict harm reduction policy ensuringsafe injection practices; however, compared to IST, it wason a smaller scale [11]. In many settings around the world,except for some European countries, liabilities related toproviding assistance with injecting of illicit drugs posechallenges for developing harm reduction interventionsother than provision of safer injection education [17].While a recent study has suggested a declining impactof assisted injecting on HIV incidence in Vancouver[18], little is known about changes in the prevalence andthe associated harms of assisted injection over time inthis setting, and how they may differ across the genders.Therefore, we conducted a gender-based analysis amongPWID in Vancouver to examine trends in the rates of re-quiring assisted injecting over time. In sub-analyses, wealso examined changes in the correlates of and reasonsfor requiring assisted injecting over time.MethodsStudy designData were collected from the Vancouver Injection DrugUsers Study (VIDUS), a prospective cohort study ofPWID in Vancouver, Canada. Recruitment of VIDUSparticipants began in the Downtown Eastside neighbor-hood in May 1996. The VIDUS cohort has been de-scribed in detail previously [19]. In brief, eligibilitycriteria include being aged ≥18 years, injecting illicitdrugs at least once in the preceding month, living ingreater Vancouver area, and providing informed consent.At baseline and subsequent semi-annual follow-up inter-views, participants complete an interviewer-administeredquestionnaire, which includes items on sociodemo-graphics, drug use patterns, and other characteristicsand exposures. At each visit, participants provide bloodsamples to test for HIV and hepatitis C and receive CAD$30 in monetary compensation. The VIDUS cohort hasbeen approved by the University of British Columbia/Providence Healthcare Research Ethics Board.For the present analyses, participants were eligible ifthey completed the baseline assessment between Decem-ber 1, 2005 and May 31, 2014. The sample was furtherrestricted to those who reported having injected drugs inthe previous 6 months for each subsequent follow-up.Study variablesThe main outcome of interest was assisted injecting inthe past 6 months, defined as responding “yes” to thequestion: “In the last 6 months, did someone help youinject?” The primary explanatory variable was calendaryear of interview (per year later). Based on the literature[2, 4, 20], we also selected a range of secondary explana-tory variables that we hypothesized to be associated withassisted injecting. Binary variables (yes vs. no) includedthe following: Caucasian ancestry; not completing highschool education; currently in a stable relationship;homelessness; sex work, defined as exchanging sex forgifts, food, shelter, clothes, etc.; incarceration; and beinga victim of violence; ≥daily heroin injection; ≥dailycocaine injection; ≥daily crystal methamphetamine injec-tion; ≥daily prescription opioid injection; any public in-jection drug use; syringe borrowing; non-fatal overdose;and ever learned safe injection technique by a healthcareprovider assessed at baseline. A continuous variableincluded years injecting (per 10 years longer). Time-varying sociodemographic and drug use variables referredto the previous 6 months unless otherwise indicated.Statistical analysesAll analyses were stratified by gender. First, we examinedthe baseline sample characteristics stratified by reports ofassisted injecting using Pearson’s chi-squared test (for bin-ary variables) and Wilcoxon rank-sum test (for continuousPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 2 of 8variables). Fisher’s exact test was used when one or moreof the cells contained expected values less than or equal tofive. We also plotted proportions of participants reportingassisted injecting over the calendar year of interview.Since the analyses of assisted injecting included serialmeasures for each participant, we used generalized esti-mating equations (GEE) with logit link, which providedstandard errors adjusted by multiple observations perperson using an exchangeable correlation structure. Toexamine the relationship between the calendar year ofinterview and assisted injecting, we fit multivariable GEEmodels using a conservative confounding model selec-tion approach [21]. We included all variables that wereassociated with assisted injecting in unadjusted analysesat p < 0.10 in a full multivariable model, and used a step-wise approach to fit a series of reduced models. Aftercomparing the value of the coefficient of the calendaryear of interview in each reduced model, we droppedthe secondary variable associated with the smallest rela-tive change. We continued this iterative process untilthe minimum change exceeded 5 %.Because each participant contributed a different num-ber of study visits, we further conducted a sensitivityanalysis using independence estimating equations (IEE)with the same confounding model selection approach.IEE examined the relationship between the calendar yearof interview and assisted injecting, allowing for potentialinformative cluster size in the analysis [22].In a sub-analysis to identify changes in the correlatesof assisted injecting over time, we divided the studyperiod into two sub-periods (June 2006–November 2009and December 2009–May 2014) based on the VANDUIST operation period and fit multivariable models separ-ately. Both periods included the same set of variablesdescribed above with the only difference being the pres-ence/absence of a variable assessing the use of theVANDU IST in the previous 6 months (yes vs. no). Wedetermined the covariates to be included in the finalmultivariable models using an a priori-defined model-building procedure. The procedure started with all co-variates that were associated with assisted injecting atthe level of p < 0.10 in unadjusted analyses, and pro-ceeded using a backward selection process while twovariables (i.e., years injecting and accessing VANDUIST) were forced to remain in the models. The finalmultivariable models with the lowest quasi-likelihoodunder the independence model criterion value were se-lected [23].Lastly, we also examined changes in the reasons for re-quiring assisted injecting over time. Since the questionasking about reasons for assisted injecting was removedfrom the questionnaire during some periods in thefollow-up, only the data collected during the first andlast 18 months of the study period (i.e., December2005–May 2007 and December 2012–May 2014) wereavailable for this analysis. We used Pearson’s chi-squaredtest (or Fisher’s exact test when one or more of the cellscontained expected values less than or equal to five) tocompare the reasons for assisted injecting between thetwo 18-month periods. All p values were two-sided. Allstatistical analyses were performed using the SAS soft-ware version 9.4 (SAS, Cary, NC).ResultsSummary statisticsA total of 1119 participants, including 376 (33.6 %) fe-male PWID, were included in this study. Of these, 151(20.3 %) males and 127 (33.8 %) females reported requir-ing assisted injecting in the previous 6 months at base-line. Table 1 shows the baseline sample characteristicsstratified by requiring assisted injecting in the previous6 months. As can be seen in Fig. 1, rates of requiring as-sistance with injecting have decreased for both malesand females over time. In 2006, 37.0 % of females reportedassisted injecting in the previous 6 months compared to25.6 % in 2014. Similarly, in 2006, 21.9 % of males re-ported assisted injecting in the previous 6 months com-pared to 13.8 % in 2014.Primary analysesThe declining trends in assisted injecting were consistentwith the results of the multivariable GEE analyses. Asshown in Table 2, after an extensive confounder adjust-ment, the calendar year of interview remained independ-ently and negatively associated with assisted injectingamong both males (adjusted odds ratio [AOR] 0.95, 95 %confidence interval [CI] 0.92–0.99) and females (AOR0.93, 95 % CI 0.89–0.97).Consistent with the GEE analyses, the sensitivity ana-lysis using IEE also found declining trends in assistedinjecting among both males (for the calendar year ofinterview, AOR 0.95, 95 % CI 0.91–0.99) and females(AOR 0.93, 95 % CI 0.88–0.98).Sub-analysesIn the multivariable GEE analyses of factors associatedwith assisted injecting during two time periods, June2006–November 2009 and December 2009–May 2014,there were some persistent and changing correlates ofassisted injecting between the genders as well as betweenthe two time periods. Among males, during the first timeperiod, sex work (AOR 3.75, 95 % CI 1.68–8.33) andinjecting in public (AOR 1.41, 95 % CI 1.07–1.85) were in-dependently associated with assisted injecting. During thesecond time period, daily crystal meth injection (AOR2.98, 95 % CI 1.93–4.61), injecting in public (AOR 2.00,95 % CI 1.46–2.73), and syringe borrowing (AOR 1.88,95 % CI 1.02–3.48) were independently associated withPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 3 of 821.918.816.514.213.2 12.714.819.113.837.0 37.840.528.926.221.223.528.325.6010203040502006 2007 2008 2009 2010 2011 2012 2013 2014Percentage requiring assisted injectiontYear of InterviewMaleFemaleFig. 1 Rates of requiring assistance with injecting among PWID by year of interview. PWID people who inject drugsTable 1 Baseline sample characteristics stratified by requiring assistance with injecting in the previous 6 months among PWID inVancouver, Canada (n = 1119)Characteristic Males (n = 743) Females (n = 376)Requiring assistance with injectinga p value Requiring assistance with injectinga p valueYes (%) No (%) Yes (%) No (%)151 (20.3) 592 (79.7) 127 (33.8) 249 (66.2)Demographic and social characteristicsAge (median, IQR) 43 (36–48) 42 (35–48) 0.596 36 (28–43) 37 (29–45) 0.605Caucasian 100 (66.2) 409 (69.1) 0.499 70 (55.1) 125 (50.2) 0.367<High school diploma 78 (51.7) 249 (42.1) 0.039 65 (51.2) 141 (56.6) 0.368In a stable relationship 40 (26.5) 148 (25.0) 0.683 55 (43.3) 96 (38.6) 0.390Homelessa 63 (41.7) 230 (38.9) 0.519 57 (44.9) 86 (34.5) 0.051Sex worka 7 (4.6) 11 (1.9) 0.069 54 (42.5) 102 (41.0) 0.822Incarcerateda 29 (19.2) 115 (19.4) 0.951 28 (22.1) 33 (13.3) 0.031Victim of violencea 50 (33.1) 137 (23.1) 0.013 43 (33.9) 51 (20.5) 0.007Drug use-related characteristicsYears injecting (median, IQR) 20 (8–30) 19 (12–31) 0.347 12 (8–24) 16 (10–24) 0.044≥Daily heroin injectiona 52 (34.4) 187 (31.6) 0.504 62 (48.8) 86 (34.5) 0.007≥Daily cocaine injectiona 20 (13.3) 52 (8.8) 0.100 18 (14.2) 27 (10.8) 0.347≥Daily crystal meth injectiona 14 (9.3) 24 (4.1) 0.009 8 (6.3) 9 (3.6) 0.229≥Daily PO injectiona 8 (5.3) 47 (7.9) 0.269 7 (5.5) 12 (4.8) 0.772Injecting in publica 77 (51.0) 242 (40.9) 0.021 67 (52.8) 92 (37.0) 0.003Syringe borrowinga 15 (9.9) 56 (9.5) 0.860 22 (17.3) 21 (8.4) 0.011Non-fatal overdosea 18 (11.9) 36 (6.1) 0.014 14 (11.0) 23 (9.2) 0.608Accessed VANDU InjectionSupport Teama26 (17.2) 67 (11.3) 0.014 17 (13.4) 26 (10.4) 0.574Ever learned safe injection techniqueby healthcare provider34 (22.5) 124 (21.0) 0.932 37 (29.1) 45 (18.1) 0.026PWID people who inject drugs, IQR interquartile range, PO prescription opioid, VANDU Vancouver Area Network of Drug UsersaActivities in the previous 6 monthsPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 4 of 8assisted injecting. Among females, during the first timeperiod, sex work (AOR 1.45, 95 % CI 1.08–1.93), injectingin public (AOR 1.97, 95 % CI 1.48–2.62), and syringe bor-rowing (AOR 1.53, 95 % CI 1.10–2.11) were independ-ently associated with requiring assistance with injecting.During the second time period, daily heroin injection(AOR 1.63, 95 % CI 1.17–2.28), injecting in public (AOR1.45, 95 % CI 1.08–1.96), and syringe borrowing (AOR2.15, 95 % CI 1.24–3.74) were independently associatedwith assisted injecting.Table 3 shows reasons for assisted injecting during thefirst and last 18 months of the study period, DecemberTable 2 Univariable and multivariable GEE analyses of factors associated with requiring assistance with injecting among PWID inVancouver, Canada (n = 1119)Characteristic Males FemalesUnadjusted OR Adjusted OR Unadjusted OR Adjusted OR(95 % CI) (95 % CI) (95 % CI) (95 % CI)Interview year(per year later) 0.95 (0.92–0.99) 0.95 (0.92–0.99) 0.90 (0.87–0.94) 0.93 (0.89–0.97)Ethnicity(Caucasian vs. other) 1.09 (0.80–1.49) 1.29 (0.91–1.81)Education(<high school diploma vs. ≥high school diploma) 1.14 (0.85–1.53) 0.95 (0.66–1.35)Currently in a stable relationship(yes vs. no) 1.20 (0.99–1.47) 1.05 (0.86–1.28)Homelessa(yes vs. no) 1.10 (0.91–1.32) 1.53 (1.23–1.90)Sex worka(yes vs. no) 2.67 (1.48–4.80) 2.17 (1.18–3.99) 1.48 (1.21–1.82)Incarcerateda(yes vs. no) 1.08 (0.86–1.34) 1.57 (1.19–2.09)Victim of violencea(yes vs. no) 1.35 (1.13–1.62) 1.24 (1.03–1.48) 1.56 (1.26–1.93) 1.31 (1.06–1.62)Years since first injection(per 10 years longer) 0.85 (0.75–0.97) 0.60 (0.49–0.73) 0.80 (0.65–0.98)Heroin injectiona(≥daily vs. <daily) 1.37 (1.15–1.63) 1.53 (1.23–1.90)Cocaine injectiona(≥daily vs. <daily) 1.56 (1.23–1.98) 0.92 (0.70–1.22)Crystal meth injectiona(≥daily vs. <daily) 2.11 (1.49–2.99) 2.20 (1.54–3.14) 0.99 (0.53–1.87)PO injectiona(≥daily vs. <daily) 1.01 (0.77–1.33) 0.98 (0.65–1.48)Injecting in publica(yes vs. no) 1.67 (1.41–1.97) 1.56 (1.31–1.85) 1.90 (1.57–2.30) 1.59 (1.29–1.96)Syringe borrowinga(yes vs. no) 1.38 (1.07–1.77) 1.96 (1.54–2.49) 1.47 (1.14–1.91)Non-fatal overdosea(yes vs. no) 1.56 (1.20–2.03) 1.23 (0.89–1.70)Ever learned safe injection technique by healthcare provider(yes vs. no) 1.05 (0.75–1.47) 1.93 (1.26–2.96) 1.80 (1.16–2.79)PWID people who inject drugs, PO prescription opioid, OR odds ratio, CI confidence intervalaActivities/events in the past 6 monthsPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 5 of 82005–May 2007 and December 2012–May 2014. Asshown, the three most common reasons for males re-quiring assistance with injecting during the first18 months included having bad veins/no veins (40.4 %),jugular injection (21.2 %), and a lack of injection tech-nique (20.5 %). In contrast, during the last 18 months,the ranking slightly changed, including jugular injection(33.3 %), bad veins/no veins (30.8 %), being anxious/dope sick (14.1 %), and vision or other disability(14.1 %). Significantly more males reported jugular injec-tion to be a reason for assisted injecting in the secondcompared to first period (p = 0.045). Among females, themost common reasons during the first 18 months in-cluded having bad veins/no veins (41.7 %), jugular injec-tion (37.4 %), and a lack of injection technique (16.5 %).Again, the ranking during the last 18 months slightlychanged and included jugular injection (45.0 %), badveins/no veins (30.0 %), and being anxious/dope sick(21.7 %). Significantly more females reported being anx-ious/dope sick to be a reason for assisted injecting in thesecond compared to first time period (p = 0.016).DiscussionIn our study, rates of assisted injecting in the previous6 months have declined between 2006 and 2014 for bothmales (21.9 to 13.8 %) and females (37.0 to 25.6 %). Thedeclining trends were consistent with the results of mul-tivariable GEE analyses in which, after extensive con-founder adjustments, the calendar year of interviewremained independently and negatively associated withassisted injecting among both genders. Further, syringeborrowing remained independently and positively associ-ated with assisted injecting throughout the study periodamong females and in more recent years among males.In the last 18-month period (between December 2012and May 2014), the top three commonly reported rea-sons for assisted injecting were similar between malesand females and included jugular injection, bad veins/noveins, and being anxious/dope sick. For both genders,proportions of participants reporting a lack of injectiontechnique as a reason for assisted injecting significantlydecreased in more recent years.We have demonstrated a significant decline in therates of assisted injecting for both male and femalePWID over time even after adjusting for a range of po-tential confounders. To our knowledge, this is the firststudy examining trends in rates of assisted injecting overtime. The declining rates among PWID in this settingare encouraging and may be related to increased aware-ness of the risks associated with assisted injecting due toimproved access to harm reduction information and in-terventions. Although the present study did not directlyexamine whether access to such interventions helpedPWID stop assisted injecting, our findings that propor-tions of PWID reporting “a lack of injection technique”as a reason for requiring assisted injecting significantlydecreased among both genders in more recent yearssuggest that this might have been the case for somePWID. However, it is important to note that rates ofassisted injecting in recent years continue to be highdespite the decline demonstrated in this study. This isparticularly true for females, which is consistent withprevious studies demonstrating higher rates of assistedinjecting among females than males [1, 2, 4]. Researchhas highlighted the social and structural context withinwhich assisted injecting commonly occurs, including therole of social and interpersonal dynamics as well as so-cial rules of providing money or drugs in exchange forassistance [20]. For females, assisted injecting is often afeature of intimate or romantic relationships where malepartners commonly control the drugs to be injected [14,20]. This has been argued to further subordinate womenwithin drug scenes and increasing their vulnerability tonegative health consequences such as blood-borne infec-tions [11, 24, 25]. Thus, we recommend that future in-terventions examine ways of addressing the genderdisparity in rates of assisting injecting, including consid-eration of the social and structural context.Our findings support the existing literature by demon-strating that syringe borrowing has continued to beTable 3 Reasons for assisted injecting among PWID during two time periods (December 2005–May 2007 and December 2012–May 2014)Reason for needing help Males (n = 229) Females (n = 175)December 2005–May 2007 (%)December 2012–May 2014 (%)p value December 2005–May 2007 (%)December 2012–May 2014 (%)p value151 (65.9) 78 (34.1) 115 (65.7) 60 (34.3)Lack of injection technique 31 (20.5) 8 (10.3) 0.050 19 (16.5) 2 (3.3) 0.013Bad veins/no veins 61 (40.4) 24 (30.8) 0.153 48 (41.7) 18 (30.0) 0.128Anxious/dope sick 22 (14.6) 11 (14.1) 0.924 10 (8.7) 13 (21.7) 0.016Jugular injection 32 (21.2) 26 (33.3) 0.045 43 (37.4) 27 (45.0) 0.329Vision or other disability 24 (15.9) 11 (14.1) 0.721 17 (14.8) 7 (11.7) 0.570Other reasons 7 (4.6) 9 (11.5) 0.052 4 (3.5) 1 (1.7) 0.662PWID people who inject drugsPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 6 of 8common among PWID requiring assistance with inject-ing, particularly among women. In the context of intim-ate relationships, qualitative findings have demonstratedthat women are often injected by controlling “boy-friends” [11]. This increases the likelihood that boy-friends will inject themselves first and then using thesame syringe on them after. In other words, genderedpower dynamics play an important role in increasing therisk of syringe borrowing among women who rely onassisted injecting. A concerning finding of our study isthat the association between assisted injecting and syr-inge borrowing appears to have strengthened in recentyears (compared to the first time period studied). Wehypothesize that this may be due to a lack of specific in-terventions targeting syringe sharing among those whorequire assistance with injecting.Our study demonstrates some noteworthy trends indrug use patterns associated with assisted injecting overtime. Consistent with previous studies [26], injecting inpublic was identified as a persistent correlate of assistedinjecting for both males and females throughout thestudy period. This is concerning as injecting safely inpublic is often challenged by unhygienic locations, inter-ruption, violence, and police presence [26–28], all ofwhich increase risks to the harmful effects of assistedinjecting. Our study also highlights some changingtrends in drug use patterns. Daily crystal meth injectionwas identified as an independent correlate of assistedinjecting among males in recent years. There has beenan increasing trend in crystal meth injections in Vancou-ver in recent years [29]. People who inject drugs of ashort half-life, such as crystal meth, tend to inject manytimes a day and are vulnerable to vascular damage andblood-borne disease acquisition [30]. They may also sub-sequently progress to injecting in more risky ways, suchas the jugular vein injecting [30], which is associatedwith requiring assistance with injecting [31]. Our findingthat jugular injection as a reason for assisted injectinghas increased among males in recent years supports thishypothesis, although loss of access to peripheral veins asthe VIDUS cohort ages is another possible explanationfor transitioning to jugular injections. Among females,daily heroin injection was identified as an independentcorrelate of assisted injecting in recent years, and anx-iousness and dope sickness as a reason for requiring as-sistance with injecting has also increased in recent yearsamong females. Dope sickness is common in peoplewithdrawing from heroin; thus, the increase in anxious-ness and dope sickness is consistent with the emergenceof daily heroin injection as an independent correlate ofassisted injecting among females. However, our studywas unable to examine why different drugs were identi-fied as independent correlates between the genders. Fur-ther qualitative research is needed to explore this issue.The findings presented in this study have a number ofimportant implications for policy and research. We agreewith previous researchers [1, 11, 12] that allowingassisted injecting at SIFs would result in potential healthbenefits for PWID. Not only would it likely decrease theoverall risky rate of assisted injecting (e.g., through ex-tending the reach of the SIFs to a large subgroup ofPWID, who require manual assistance with injecting andare at a heightened risk of harms associated with assistedinjecting due to the social and structural factors), allow-ing assisted injecting at SIFs would also decrease thenumber of PWID who inject in public outdoor spacesthereby decreasing their vulnerability to harms associ-ated with public outdoor assisted injecting [12]. Further-more, permitting assisted injecting at SIFs would alsoprovide a significant sub-population of PWID with ac-cess to clean syringes, thereby reducing their risk ofblood-borne infections. Indeed, a previous evaluation ofan unsanctioned peer-run SIF that allowed assistedinjecting demonstrated the feasibility and potential bene-fits of this approach [32], indicating that it reshaped thesocial and structural contexts surrounding assisted injec-tion to reduce exposure to HIV risks and drug sceneviolence. Secondly, previous studies have also demon-strated that trained peer educators can provide helpfuleducation and safer injections to PWID who require as-sistance injecting [3, 11]. Therefore, access to safe peer-driven assisted injecting services both within SIFs as wellas in the community, such as the VANDU IST, shouldbe promoted.This study has some limitations. First, as the VIDUSstudy is not a random sample, our study findings maynot be generalizable to PWID at large. Second, the self-reported data may have been affected by respondingbias, including socially desirable responding and recallbias. If these sources of bias were present, the trueprevalence of risk behaviors assessed would be underes-timated, which would bias our findings towards the null.Third, as with all observational research, the estimatedrelationships between the explanatory variables andassisted injecting may be under the influence of unmeas-ured confounding, although we sought to address thisbias through multivariable adjustment involving key po-tential demographic, behavioral, social/structural, andenvironmental confounders.ConclusionsIn summary, our study demonstrated that rates of assistedinjecting have significantly declined among our sample ofPWID in Vancouver between 2006 and 2014, which is en-couraging as assisted injecting is a major risk factor for anumber of negative health consequences. However, ratesof assisted injecting remain high, especially amongwomen. We urge policy makers to reconsider the legalPedersen et al. Harm Reduction Journal  (2016) 13:2 Page 7 of 8framework of existing SIFs to allow assisted injecting asthis would reduce a number of harmful consequences forsome of the most marginalized and vulnerable PWID.AbbreviationsCI: confidence interval; IQR: interquartile range; OR: odds ratio;PO: prescription opioid; PWID: people who inject drugs; VANDU: VancouverNetwork of Drug Users.Competing interestsThe authors declare that they have no competing interests.Authors’ contributionsJSP, KH, and TK designed the study and wrote the protocol. PN and HDconducted the statistical analyses. JSP wrote the first draft of the manuscriptand all authors contributed to and have 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. The study was supportedby the US National Institutes of Health (U01DA038886, R01DA033147). Thisresearch was undertaken, in part, thanks to funding from the Canada ResearchChairs program through a Tier 1 Canada Research Chair in Inner City Medicinewhich supports Dr. Evan Wood. Dr. Kanna Hayashi is supported by theCanadian Institutes of Health Research New Investigator Award (MSH-141971).Funding from the Michael Smith Foundation for Health Research supportsDr. Small. The funders had no role in the design, in the collection, analysis,and interpretation of the data; in the writing of the manuscript; or in thedecision to submit the manuscript for publication.Author details1Cumming School of Medicine, University of Calgary, 3330 Hospital DriveNW, Calgary, ABT2N 4N1Canada. 2British Columbia Centre for Excellence inHIV/AIDS, St. Paul’s Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6,Canada. 3Faculty of Health Sciences, Simon Fraser University, 8888 UniversityDrive, Burnaby, BC 15A 1S6, Canada. 4Department of Medicine, University ofBritish Columbia, St. Paul’s Hospital, 608-1081 Burrard Street, Vancouver, BCV6Z 1Y6, Canada. 5B.C. Centre for Excellence in HIV/AIDS, University of BritishColumbia, St. Paul’s Hospital, 608-1081 Burrard Street, Vancouver, BC V6Z 1Y6,Canada.Received: 5 November 2015 Accepted: 24 December 2015References1. 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Summary of findings from theevaluation of a pilot medically supervised safer injecting facility. CMAJ.2006;175:1399–404.16. Wood RA, Wood E, Lai C, Tyndall MW, Montaner JS, Kerr T. Nurse-deliveredsafer injection education among a cohort of injection drug users: evidencefrom the evaluation of Vancouver’s supervised injection facility. Int J DrugPolicy. 2008;19:183–8.17. Solaia S, Dubois-Arbera F, Benninghoffa F, Benaroyo L. Ethical reflectionsemerging during the activity of a low threshold facility with supervised drugconsumption room in Geneva, Switzerland. Int J Drug Policy. 2006;17:17–22.18. Lappalainen L, Kerr T, Hayashi K, Dong H, Wood E. Decreasing impact ofrequiring assistance injecting on HIV incidence. J Acquir Immune DeficSyndr. 2015;69:e40–2.19. Strathdee SA, Patrick DM, Currie SL, Cornelisse PG, Rekart ML, Montaner JS,et al. Needle exchange is not enough: lessons from the Vancouver injectingdrug use study. AIDS. 1997;11:F59–65.20. 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Physical injecting sites among injecting drug usersin Sydney, Australia. Drug Alcohol Depend. 2001;62:77–82.31. Rafful C, Wagner KD, Werb D, Gonzalez-Zuniga PE, Verdugo S, Rangel G, etal. Prevalence and correlates of neck injection among people who injectdrugs in Tijuana, Mexico. Drug Alcohol Rev. 2015;34:630–6.32. Kerr T, Oleson M, Tyndall MW, Montaner J, Wood E. A description of apeer-run supervised injection site for injection drug users. J UrbanHealth. 2005;82:267–75.Pedersen et al. Harm Reduction Journal  (2016) 13:2 Page 8 of 8

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