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1.  Associations Between Childhood Trauma and Non-Fatal Overdose Among People Who Inject Drugs 
Addictive behaviors  2014;43:83-88.
Introduction
Although people who inject drugs (IDU) remain at a high risk of accidental overdose, interventions that address overdose remain limited. Accordingly there is a continuing need to identify psychological and social factors that shape overdose risk. Despite being reported frequently among IDU, childhood trauma has received little attention as a potential risk factor for overdose. This study aims to evaluate relationships between non-fatal overdose and five forms of childhood maltreatment among a cohort of IDU in Vancouver, Canada.
Methods
Data was obtained from two prospective cohorts of IDU between December 2005 and May 2013. Multivariate generalized estimating equations (GEE) were used to explore relationships between five forms of childhood trauma and non-fatal overdose, adjusting for potential confounders.
Results
During the study period, 1697 IDU, including 552 (32.5%) women, were followed. At baseline, 1136 (67.0%) participants reported at least one form of childhood trauma, while 4–9% reported a non-fatal overdose at each semi-annual follow-up. In multivariate analyses, physical [adjusted odds ratio (AOR): 1.36, 95% confidence interval (CI): 1.08–1.71], sexual (AOR: 1.48, CI: 1.17–1.87), and emotional abuse (AOR: 1.54, CI: 1.22–1.93) and physical neglect (AOR: 1.28, CI: 1.01–1.62) were independently associated with non-fatal overdose (all p < 0.05).
Conclusions
Childhood trauma was common among participants, and reporting an experience of trauma was positively associated with non-fatal overdose. These findings highlight the need to provide intensive overdose prevention to trauma survivors and to incorporate screening for childhood trauma into health and social programs tailored to IDU.
doi:10.1016/j.addbeh.2014.12.014
PMCID: PMC4304975  PMID: 25588793
Childhood abuse; Childhood neglect; Childhood maltreatment; Injection drug use; Non-fatal overdose
2.  High-intensity cannabis use associated with lower plasma HIV-1 RNA viral load among recently-infected people who use injection drugs 
Drug and alcohol review  2014;34(2):135-140.
Introduction and Aims
Cannabis use is common among people who are living with HIV/AIDS. While there is growing pre-clinical evidence of the immunomodulatory and anti-viral effects of cannabinoids, their possible effects on HIV disease parameters in humans is largely unknown. Thus, we sought to investigate the possible effects of cannabis use on plasma HIV-1 RNA viral loads among recently-seroconverted illicit drug users.
Design and Methods
We used data from two linked longitudinal observational cohorts of people who use injection drugs. Using multivariable linear mixed-effects modeling, we analysed the relationship between pVL and high-intensity cannabis use among participants who seroconverted following recruitment.
Results
Between May, 1996 and March, 2012, 88 individuals seroconverted after recruitment and were included in these analyses. Median pVL in the first 365 days among all seroconverters was 4.66 log10 c/mL. In a multivariable model, at least daily cannabis use was associated with 0.51 log10 c/mL lower pVL (β = −0.51, Standard Error = 0.170, p-value = 0.003).
Discussion
Consistent with the findings from recent in vitro and in vivo studies, including one conducted among lentiviral-infected primates, we observed a strong association between cannabis use and lower pVL following seroconversion among illicit drug-using participants.
Conclusion
Our findings support the further investigation of the immunomodulatory or anti-viral effects of cannabinoids among individuals living with HIV/AIDS.
doi:10.1111/dar.12223
PMCID: PMC4363114  PMID: 25389027
Plasma HIV-1 RNA viral load; cannabis; cannabinoids; HIV infection; disease progression
3.  Denial of Prescription Analgesia Among People Who Inject Drugs in a Canadian Setting 
Drug and alcohol review  2014;34(2):221-228.
Introduction and Aims
Despite the high prevalence of pain among people who inject drugs (PWID), clinicians may be reluctant to prescribe opioid-based analgesia to those with a history of drug use or addiction. We sought to examine the prevalence and correlates of PWID reporting being denied prescription analgesia (PA). We also explored reported reasons for and actions taken after being denied PA.
Design and Methods
Using data from two prospective cohort studies of PWID in Vancouver, Canada, multivariate logistic regression was used to identify the prevalence and correlates of reporting being denied PA. Descriptive statistics were used to characterize reasons for denials and subsequent actions.
Results
Approximately two thirds (66.5%) of our sample of 462 active PWID reported having ever been denied PA. We found that reporting being denied PA was significantly and positively associated with having ever been enrolled in methadone maintenance treatment (MMT) (adjusted odds ratio [AOR]=1.76, 95%CI: 1.11–2.80) and daily cocaine injection (AOR=2.38, 95%CI: 1.00–5.66). The most commonly reported reason for being denied PA was being accused of drug-seeking (44.0%). Commonly reported actions taken after being denied PA included buying the requested medication off the street (40.1%) or obtaining heroin to treat pain (32.9%)
Discussion and Conclusions
These findings highlight the clinical challenges of addressing perceived pain control needs and the need for strategies to prevent high-risk methods of self-managing pain, such as obtaining diverted medications or illicit substances for pain. Such strategies may include integrated pain management guidelines within MMT and other substance use treatment programs.
doi:10.1111/dar.12226
PMCID: PMC4657858  PMID: 25521168
pain; prescription opioids; diversion; drug seeking; methadone
4.  Factors associated with inability to access addiction treatment among people who inject drugs in Vancouver, Canada 
Background
Addiction treatment is an effective strategy used to reduce drug-related harm. In the wake of recent developments in novel addiction treatment modalities, we conducted a longitudinal data analysis to examine factors associated with inability to access addiction treatment among a prospective cohort of persons who inject drugs (PWID).
Methods
Data were derived from two prospective cohorts of PWID in Vancouver, Canada, between December 2005 and November 2013. Using multivariate generalized estimating equations, we examined factors associated with reporting an inability to access addiction treatment.
Results
In total, 1142 PWID who had not accessed any addiction treatment during the six months prior to interview were eligible for this study, including 364 women (31.9 %). Overall, 188 (16.5 %) reported having sought but were ultimately unsuccessful in accessing addiction treatment at least once during the study period. In multivariate analysis, factors independently and positively associated with reporting inability to access addiction treatment included: binge drug use (Adjusted Odds Ratio [AOR] = 1.65), being a victim of violence (AOR = 1.77), homelessness (AOR = 1.99), and having ever accessed addiction treatment (AOR = 2.33); while length of time injecting was negatively and independently associated (AOR = 0.98) (all p < 0.05).
Conclusions
These findings suggest that sub-populations of PWID were more likely to report experiencing difficulty accessing addiction treatment, including those who may be entrenched in severe drug addiction and vulnerable to violence. It is imperative that additional resources go into ensuring treatment options are readily available when requested for these target populations.
doi:10.1186/s13011-016-0053-6
PMCID: PMC4766680  PMID: 26916425
Injection drug use; Addiction treatment; Homelessness; Drug or alcohol treatment; Binge drug use; Violence
5.  HIV, drugs and the legal environment 
A large body of scientific evidence indicates that policies based solely on law enforcement without taking into account public health and human rights considerations increase the health risks of people who inject drugs (PWIDs) and their communities. Although formal laws are an important component of the legal environment supporting harm reduction, it is the enforcement of the law that affects PWIDs' behavior and attitudes most acutely. This commentary focuses primarily on drug policies and policing practices that increase PWIDs' risk of acquiring HIV and viral hepatitis, and avenues for intervention. Policy and legal reforms that promote public health over the criminalization of drug use and PWID are urgently needed. This should include alternative regulatory frameworks for illicit drug possession and use. Changing legal norms and improving law enforcement responses to drug-related harms requires partnerships that are broader than the necessary bridges between criminal justice and public health sectors. HIV prevention efforts must partner with wider initiatives that seek to improve police professionalism, accountability, and transparency and boost the rule of law. Public health and criminal justice professionals can work synergistically to shift the legal environment away from one that exacerbates HIV risks to one that promotes safe and healthy communities.
doi:10.1016/j.drugpo.2014.09.001
PMCID: PMC4346482  PMID: 25265900
HIV; law; policing; injection drug use; harm reduction
6.  DEVELOPMENT OF A BRIEF SUBSTANCE USE SENSATION SEEKING SCALE: VALIDATION AND PREDICTION OF INJECTION-RELATED BEHAVIORS 
AIDS and behavior  2015;19(2):352-361.
Sensation seeking, a personality trait, has been shown to predict engagement in high-risk behaviors. However, little is known regarding the impact of sensation seeking on substance use among street youth. We therefore sought to modify a sensation seeking scale (SSS) for use among this population. Street youth from the Vancouver-based At-Risk Youth Study (n = 226) completed the modified SSS. Exploratory and confirmatory factor analysis (EFA/CFA) were undertaken to establish the scale’s dimensionality and internal validity. The association between SSS score and injection-related behaviors was tested using generalized estimating equation (GEE) analysis. EFA results indicated scale unidimensionality. The comparative fit index (CFI) suggested acceptable fit (CFI = 0.914). In multivariate analysis, sensation seeking was independently associated with injection drug use, crystal methamphetamine use, polysubstance use, and binge drug use (all p < 0.05). Our findings provide preliminary support for the use of the modified SSS among street youth.
doi:10.1007/s10461-014-0875-z
PMCID: PMC4450886  PMID: 25119056
injection; crystal methamphetamine; sensation seeking; street youth; injection initiation
7.  Declining trends in the rates of assisted injecting: a prospective cohort study 
Background
Assisted injecting has been associated with increased risk of blood-borne infections, overdose, and other harms among people who inject drugs (PWID), particularly women. Given the changing availability of relevant harm reduction interventions in Vancouver, Canada, in recent years, we conducted a gender-based analysis to examine 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 multivariable generalized estimating equations to examine trends in assisted injecting and identify the correlates during two periods: June 2006–November 2009 and December 2009–May 2014.
Results
Among 1119 participants, 376 (33.6 %) were females. Rates of assisted injecting declined between 2006 and 2014 among males (21.9 to 13.8 %) and females (37.0 to 25.6 %). In multivariable analyses, calendar year of interview also remained independently and negatively associated with assisted injecting among males (adjusted odds ratio [AOR] 0.95, 95 % confidence interval [CI] 0.92–0.99) and females (AOR 0.93, 95 % CI 0.89–0.97). Syringe borrowing 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 during 2009–2014 among males (AOR 1.88, 95 % CI 1.02–3.48).
Conclusions
Our findings demonstrate assisted injecting has significantly decreased for both males and females 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 to these vulnerable sub-populations of PWID.
doi:10.1186/s12954-016-0092-3
PMCID: PMC4728798  PMID: 26817687
Assisted injecting; Injection drug use; Harm reduction; Vancouver
8.  Inability to access addiction treatment predicts injection initiation among street-involved youth in a Canadian setting 
Background
Preventing injection drug use among vulnerable youth is critical for reducing serious drug-related harms. Addiction treatment is one evidence-based intervention to decrease problematic substance use; however, youth frequently report being unable to access treatment services and the impact of this on drug use trajectories remains largely unexplored. This study examines the relationship between being unable to access addiction treatment and injection initiation among street-involved youth.
Methods
Data were derived from the At-Risk Youth Study (ARYS), a prospective cohort of street-involved youth aged 14–26 who use illicit drugs, from September 2005 to May 2014. An extended Cox model with time-dependent variables was used to identify factors independently associated with injection initiation.
Results
Among 462 participants who were injection naïve at baseline, 97 (21 %) initiated injection drug use over study follow-up and 129 (28 %) reported trying but being unable to access addiction treatment in the previous 6 months at some point during the study period. The most frequently reported reason for being unable to access treatment was being put on a wait list. In a multivariable Cox regression analysis, being unable to access addiction treatment remained independently associated with a more rapid rate of injection initiation (Adjusted Hazard Ratio =2.02; 95 % Confidence Interval: 1.12–3.62), after adjusting for potential confounders.
Conclusion
Inability to access addiction treatment was common among our sample and associated with injection initiation. Findings highlight the need for easily accessible, evidence-based addiction treatment for high-risk youth as a means to prevent injection initiation and subsequent serious drug-related harms.
doi:10.1186/s13011-015-0046-x
PMCID: PMC4702392  PMID: 26733043
Injection initiation; At-risk youth; Addiction treatment; Injection prevention
9.  Substance use patterns and unprotected sex among street-involved youth in a Canadian setting: a prospective cohort study 
BMC Public Health  2016;16:4.
Background
Rates of sexually transmitted infections (STI) and unplanned pregnancy are high among youth. While the intersection between drug and alcohol use and unprotected sex is well recognized, few studies have examined the relationship between substance use patterns and unprotected sex among high risk-populations such as street-involved youth.
Methods
Data were derived from the At-Risk Youth Study (ARYS), a prospective cohort of street-involved youth from Vancouver, Canada. Generalized estimating equations (GEE) were used to examine substance use patterns that were independently associated with unprotected sex, defined as (vaginal or anal) sexual intercourse without consistent condom 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, female gender (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 recent unprotected sex: injection or non-injection crystal methamphetamine use (AOR = 1.21, 95 % CI: 1.03-1.43), injection or non-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 independently associated with female gender and a wide range of substance use patterns. Evidence-based and gender-informed sexual 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 be integrated across all health and social services.
doi:10.1186/s12889-015-2627-z
PMCID: PMC4700772  PMID: 26728877
Street-youth; Unprotected sex; Addictions; Risk behaviour
10.  The Impact of Childhood Emotional Abuse on Violence among People Who Inject Drugs 
Drug and alcohol review  2014;34(1):4-9.
Introduction and Aims
Childhood emotional abuse is a known risk factor for various poor social and health outcomes. While people who inject drugs (IDU) report high levels of violence, in addition to high rates of childhood maltreatment, the relationship between childhood emotional abuse and later life violence within this population has not been examined.
Design and Methods
Cross-sectional data were derived from an open prospective cohort of IDU in Vancouver, Canada. Childhood emotional abuse was measured using the Childhood Trauma Questionnaire. We used multivariate logistic regression to examine potential associations between childhood emotional abuse and being a recent victim or perpetrator of violence.
Results
Between December 2005 and May 2013, 1437 IDU were eligible for inclusion in this analysis, including 465 (32.4%) women. In total, 689 (48.0%) reported moderate to severe history of childhood emotional abuse, while 333 (23.2%) reported being a recent victim of violence and 173 (12.0%) reported being a recent perpetrator of violence. In multivariate analysis, being a victim of violence (adjusted odds ratio = 1.49, 95% confidence interval 1.15–1.94) and being a perpetrator of violence (adjusted odds ratio = 1.58, 95% confidence interval 1.12–2.24) remained independently associated with childhood emotional abuse.
Discussion and Conclusions
We found high rates of childhood emotional abuse and subsequent adult violence among this sample of IDU. Emotional abuse was associated with both victimisation and perpetration of violence. These findings highlight the need for policies and programs that address both child abuse and historical emotional abuse among adult IDU.
doi:10.1111/dar.12133
PMCID: PMC4167988  PMID: 24635836
emotional abuse; trauma; violence; injection drug use
11.  Ongoing Impact of HIV Infection on Mortality among Persons who Inject Drugs Despite Free Antiretroviral Therapy 
Addiction (Abingdon, England)  2014;110(1):111-119.
Aims
To determine the impact of HIV infection on mortality over time among persons who inject drugs (PWID) in settings with free HIV/AIDS care.
Design and Setting
Prospective cohort study of PWID in Vancouver, Canada, recruited between May 1996 and December 2011. We ascertained morality rates and causes of death through a confidential linkage with the provincial vital statistics registry.
Participants
2283 individuals were followed for a median of 60.9 months (Interquartile range: 34.4 – 113.1) among whom 622 (27.2%) individuals were HIV-positive at baseline, and 179 (7.8%) seroconverted during follow-up.
Measurements
The primary and secondary outcomes of interests were all-cause mortality and cause of death, respectively. The main independent variable of interest was HIV serostatus (positive vs. negative). We used Cox proportional hazards regression to determine factors associated with mortality, including socio-demographic variables, drug use behaviors and other risk behaviors.
Findings
Over the study period, 491 (21.5%) individuals died. In multivariate analyses, HIV infection remained independently associated with all-cause mortality (adjusted hazard ratio = 3.15; 95% CI: 2.59 – 3.82). While all-cause mortality rates declined markedly during the study period (p < 0.001, the independent effect of HIV infection on mortality remained unchanged over time (p = 0.640). Among HIV-positive individuals, significant changes in causes of death from infectious and AIDS-related causes to non-AIDS-related etiologies were observed.
Conclusions
HIV infection continues to have a persistent impact on mortality rates among persons who inject drugs in settings with free HIV/AIDS care, though causes of death have shifted markedly from infectious and AIDS-related causes to non-AIDS-related etiologies.
doi:10.1111/add.12736
PMCID: PMC4270909  PMID: 25203392
illicit drug use; mortality; HIV/AIDS; Vancouver
12.  High-intensity cannabis use and adherence to antiretroviral therapy among people who use illicit drugs in a Canadian setting 
AIDS and behavior  2015;19(1):120-127.
Background
Cannabis is increasingly prescribed clinically and utilized by people living with HIV/AIDS (PLWHA) to address symptoms of HIV disease and to manage side effects of antiretroviral therapy (ART). In light of concerns about the possibly deleterious effect of psychoactive drug use on adherence to ART, we sought to determine the relationship between high-intensity cannabis use and adherence to ART among a community-recruited cohort of HIV-positive illicit drug users.
Methods
We used data from the ACCESS study, an ongoing prospective cohort study of HIV-seropositive illicit drug users linked to comprehensive ART dispensation records in a setting of universal no-cost HIV care. We estimated the relationship between at least daily cannabis use in the last six months, measured longitudinally, and the likelihood of optimal adherence to ART during the same period, using a multivariate linear mixed-effects model accounting for relevant socio-demographic, behavioral, clinical and structural factors.
Results
From May 2005 to May 2012, 523 HIV-positive illicit drug users were recruited and contributed 2430 interviews. At baseline, 121 (23.1%) participants reported at least daily cannabis use. In bivariate and multivariate analyses we did not observe an association between using cannabis at least daily and optimal adherence to prescribed HAART (Adjusted Odds Ratio = 1.12, 95% Confidence Interval [95% CI]: 0.76 – 1.64, p-value = 0.555.)
Conclusions
High-intensity cannabis use was not associated with adherence to ART. These findings suggest cannabis may be utilized by PLWHA for medicinal and recreational purposes without compromising effective adherence to ART.
doi:10.1007/s10461-014-0847-3
PMCID: PMC4289662  PMID: 25012624
13.  GANG INVOLVEMENT AMONG STREET-INVOLVED YOUTH IN A CANADIAN SETTING: A GENDER-BASED ANALYSIS 
Public health  2014;129(1):74-77.
Objectives
Evidence suggests that gang involvement is associated with adverse health outcomes among high-risk youth. However, few studies have investigated the prevalence and correlates of gang affiliation among this population, particularly in Canada. We examined the relationship between self-reported gang involvement and early childhood traumatic experiences, social factors, and other behaviors in a study of drug-using, street-involved youth.
Study Design
Cross-Sectional Study
Methods
Data were derived from the At-Risk Youth Study (ARYS), a prospective study of street-involved youth in Vancouver, Canada. Between June 2009 and May 2011, participants were asked questions ascertaining lifetime gang involvement and gang affiliation in one’s social network. We examined the gender-specific correlates of gang involvement using stratified log-binomial regression analyses.
Results
Among 435 eligible participants, 94 (21.6%) reported gang involvement and 206 (47.4%) reported having friends in a gang. In gender-stratified models, males involved in gangs were more likely to be of Aboriginal ancestry (prevalence ratio [PR] = 1.63, 95% confidence interval [CI]: 1.09 – 2.44), have grown up in government care (PR = 2.03, 95%CI: 1.32 – 3.12), dealt drugs (PR = 2.52, 95%CI: 1.66 – 3.85), and been incarcerated (PR = 1.40, 95%CI: 1.29 – 2.80). Women involved in gangs were more likely to have reported a history of childhood sexual abuse (PR = 3.08, 95%CI: 1.15 – 8.27).
Conclusions
These results suggest that a variety of adverse experiences in early life are associated with an increased risk of gang affiliation among street-involved youth. Primary prevention strategies aiming to avert gang initiation among high-risk youth should seek to address childhood abuse and other traumatic experiences commonly experienced by this population.
doi:10.1016/j.puhe.2014.10.017
PMCID: PMC4305456  PMID: 25542743
14.  The impact of methadone maintenance therapy on heptatis c incidence among illicit drug users. 
Addiction (Abingdon, England)  2014;109(12):2053-2059.
Aims
To determine the relationship between methadone maintenance therapy (MMT) and hepatitis C (HCV) seroconversion among illicit drug users.
Design
Generalized Estimating Equation model assuming a binomial distribution and a logit link function was used to examine for a possible protective effect of MMT use on HCV incidence.
Setting
Data from three prospective cohort studies of illicit drug users in Vancouver, Canada between 1996 and 2012.
Participants
1004 HCV antibody negative illicit drug users stratified by exposure to MMT.
Measurements
Baseline and semi-annual HCV antibody testing and standardised interviewer administered questionnaire soliciting self-reported data relating to drug use patterns, risk behaviours, detailed sociodemographic data and status of active participation in an MMT program.
Findings
184 HCV seroconversions were observed for an HCV incidence density of 6.32 [95% confidence interval [CI]: 5.44 – 7.31] per 100 person-years. After adjusting for potential confounders, MMT exposure was protective against HCV seroconversion (Adjusted Odds Ratio [AOR] = 0.47; 95% CI: 0.29 - 0.76). In sub-analyses, a dose-response protective effect of increasing MMT exposure on HCV incidence (AOR = 0.87; 95% CI: 0.78 – 0.97) per increasing 6-month period exposed to MMT was observed.
Conclusion
Participation in methadone maintenance treatment appears to be highly protective against hepatitis C incidence among illicit drug users. There appears to be a dose-response protective effect of increasing methadone exposure on hepatitis C incidence.
doi:10.1111/add.12682
PMCID: PMC4229435  PMID: 25041346
hepatitis C; HCV; illicit drug use; methadone; opioid; incident infection; seroconversion
15.  Gender Influences on Hepatitis C Incidence Among Street Youth in a Canadian Setting 
Purpose
Few studies have examined gender-based differences in the risk of hepatitis C (HCV) infection among street-involved youth. We compared rates of HCV infection among male and female street-involved youth in a Canadian setting.
Methods
The At-Risk Youth Study (ARYS) is a prospective cohort of drug-using, street-involved youth. Study recruitment and follow-up occurred in Vancouver, Canada, between September 2005 and November 2011. Eligible participants were illicit drug-using youth aged 14–26 years at enrollment, recruited by street-based outreach. We evaluated rates of HCV antibody seroconversion, measured every six months during study follow-up, and used Cox proportional hazards regression to compare risk factors for HCV incidence between male and female street youth.
Results
Among 512 HCV-seronegative youth contributing 836 person-years of follow-up, 56 (10.9%) seroconverted to HCV. Among female participants, the incidence density of HCV infection was 10.9 per 100 person-years and in males 5.1 per 100 person-years (p = 0.009). In multivariate analyses, female gender was independently associated with a higher rate of HCV seroconversion (Adjusted Hazard Ratio (AHR) = 2.01; 95% Confidence Interval [CI], 1.18 – 3.44). Risk factors were similar in gender stratified analyses and included injection heroin and injection crystal methamphetamine, although syringe sharing was only associated with HCV incidence among males.
Conclusions
Among street-involved youth in this setting, females had double the incidence of HCV seroconversion demonstrating the need for gender focused HCV prevention interventions for this population.
doi:10.1016/j.jadohealth.2014.07.006
PMCID: PMC4254041  PMID: 25240449
Hepatitis C; street youth; gender; crystal methamphetamine; heroin
16.  WILLINGNESS TO ENGAGE IN PEER-DELIVERED HIV VOLUNTARY COUNSELLING AND TESTING AMONG PEOPLE WHO INJECT DRUGS IN A CANADIAN SETTING 
Background
People who inject drugs (IDU) face unique systemic, social and individual barriers to conventional HIV voluntary counselling and testing (VCT) programs. Peer-delivered approaches represent a possible alternative to improve rates of testing among this population.
Methods
Cross-sectional data from a prospective cohort of IDU in Vancouver, Canada were collected between December 2011 and May 2012. Bivariate statistics and multivariate logistic regression were used to identify the prevalence of and factors associated with willingness to receive peer-delivered VCT.
Results
Of 600 individuals, 51.5% indicated willingness to receive peer-delivered pretest counselling, 40.7% to receive peer-delivered rapid HIV testing, and 42.8% to receive peer-delivered post-test counselling. Multivariate analyses found significant positive associations between willingness for pre-test counselling and having used Vancouver’s supervised injection facility, Insite, or being a member of VANDU (a local drug user organization) (all p < 0.05). Daily crack smoking and having used Insite were positively associated with willingness to receive peer-delivered HIV testing (p < 0.05). Willingness to receive peer-delivered post-test counselling was positively associated with male gender, daily crack smoking, having used Insite, and being a member of VANDU (p<0.05).
Conclusion
While not universally acceptable, peer-delivered VCT approaches may improve access to HIV testing among IDU.
doi:10.1136/jech-2013-203707
PMCID: PMC4654111  PMID: 24700578
Peer-delivered; Voluntary HIV counselling and testing; People who inject drugs; Vancouver
17.  Association of patterns of methadone use with antiretroviral therapy discontinuation: a prospective cohort study 
BMC Infectious Diseases  2015;15:537.
Background
Methadone maintenance therapy (MMT) is a proven treatment strategy for opioid dependent patients. Although studies have demonstrated that MMT increases contact with the medical system and improves adherence to antiretroviral therapy (ART) in HIV-positive people who inject drugs (PWID), the effect of MMT discontinuation on ART discontinuation has not been well described.
Methods
We examined the impact of continuous MMT use, MMT non-use and MMT discontinuation on the time to ART discontinuation (defined as 90 days of continuous non-use following previous enrolment) in a community-recruited prospective cohort of HIV-positive PWID followed between May 1996 and May 2013 in Vancouver, Canada. Multivariate Cox proportional hazards regression was used to examine the association between MMT use patterns and time to ART discontinuation while adjusting for socio-demographic confounders.
Results
A total of 794 HIV-positive PWID were included during the study period. In an adjusted analysis, in comparison to those who were continuously on MMT, MMT non-use (Adjusted Hazard Ratio [AHR] = 1.44, 95 % Confidence Interval [CI]: 1.19–1.73) as well as discontinuing MMT (AHR = 1.82, 95 % CI: 1.27–2.60) were both found to be independently associated with time to ART discontinuation.
Conclusions
This study reinforces the known benefits of MMT use on ART adherence and demonstrates how discontinuation of MMT is independently associated with an increased risk of ART cessation. These data highlight the importance of retaining PWID on MMT.
doi:10.1186/s12879-015-1255-7
PMCID: PMC4653887  PMID: 26586238
Methadone; Opiate substitution treatment; HIV; Antiretroviral therapy; Highly active
18.  DRUG AND HIV-RELATED RISK BEHAVIORS AFTER GEOGRAPHIC MIGRATION AMONG A COHORT OF INJECTION DRUG USERS 
AIDS and behavior  2008;14(4):854-861.
To determine whether migration impacted on drug use and HIV-related risk behaviors among injection drug users (IDU), we identified participants in a prospective cohort of IDU (Vancouver Injection Drug User Study) who had reported migrating out of Greater Vancouver between May 1996 and November 2005. We compared risk behaviors before and after a move for individuals who migrated (movers) and for a similar period for non-movers using linear growth curve analyses. In total, 1,122 individuals were included, including 430 (38.3%) women and 331 (29.5%) Aboriginal participants. Among these, 192 (17.1%) individuals reported migrating out of Greater Vancouver between 1996 and 2005 while 930 (82.9%) did not. Movers were significantly younger than non-movers: 32.0 (Interquartile Range [IQR]: 24.3–39.2) and 34.6 (IQR: 26.9–40.8) respectively. A significant decrease in those reporting unstable housing, frequent heroin and cocaine injection occurred only in movers. Our findings suggest that, in this setting, risk-taking among IDU declines following periods of migration out of Greater Vancouver.
doi:10.1007/s10461-008-9397-x
PMCID: PMC4651001  PMID: 18427970
Migration; Injection drug use; HIV risk behaviors
19.  OFFER OF FINANCIAL INCENTIVES FOR UNPROTECTED SEX IN THE CONTEXT OF SEX WORK 
Drug and alcohol review  2010;29(2):144-149.
Introduction and Aims
Commercial sex workers (CSW) are often portrayed as vectors of disease transmission. However, the role clients play in sexual risk taking and related decision making has not been thoroughly characterised.
Design and Methods
Participants were drawn from the Vancouver Injection Drug Users Study, a longitudinal cohort. Analyses were restricted to those who reported selling sex between June 2001 and December 2005. Using multivariate generalised estimating equation, we evaluated the prevalence of and factors associated with being offered money for sex without a condom.
Results
A total of 232 CSW were included in the analyses, with 73.7% reporting being offered more money for condom non-use, and 30.6% of these CSW accepting. Variables independently associated with being offered money for sex without a condom included daily speedball use [adjusted odds ratio (AOR) = 1.21, 95% confidence interval (CI): 0.23–0.62], daily crack smoking (AOR = 1.51, 95% CI: 1.04–2.19), daily heroin injection (AOR = 1.76, 95% CI: 1.27–2.43) and drug use with clients (AOR = 3.22, 95% CI: 2.37–4.37). Human immunodeficiency virus seropositivity was not significant (AOR = 0.98, 95% CI: 0.67–1.44).
Discussion and Conclusions
Findings highlight the role clients play in contributing to unprotected sex through economic influence and exploitation of CSW drug use. HIV serostatus has no bearing on whether more money is offered for sex without a condom. Novel interventions should target both CSW and clients. [Johnston CL, Callon C, Li K, Wood E, Kerr T. Offer of financial incentives for unprotected sex in the context of sex work. Drug Alcohol Rev 2009]
doi:10.1111/j.1465-3362.2009.00091.x
PMCID: PMC4646705  PMID: 20447221
sex work; injection drug use; condom use; HIV risk
20.  SURVIVAL SEX WORK INVOLVEMENT AS A PRIMARY RISK FACTOR FOR HEPATITIS C VIRUS ACQUISITION IN DRUG-USING YOUTHS IN A CANADIAN SETTING 
Objective
To examine whether there were differential rates of hepatitis C virus (HCV) incidence in injecting drug-using youths who did and did not report involvement in survival sex work.
Design
Data were derived from 2 prospective cohort studies of injecting drug users (May 1, 1996, to July 31, 2007). Analyses were restricted to HCV antibody-negative youths who completed baseline and at least 1 follow-up assessment.
Setting
Vancouver, British Columbia, Canada.
Participants
Of 3074 injecting drug users, 364 (11.8%) were youths (aged 14-24 years) with a median age of 21.3 years and a duration of injecting drug use of 3 years.
Main Exposure
Survival sex work involvement.
Main Outcome Measure
The Kaplan-Meier method and Cox proportional hazards regression were used to compare HCV incidence among youths who did and did not report survival sex work.
Results
Baseline HCV prevalence was 51%, with youths involved in survival sex work significantly more likely to be HCV antibody positive (60% vs 44%; P = .002). In baseline HCV antibody-negative youths, the cumulative HCV incidence at 36 months was significantly higher in those involved in survival sex work (68.4% vs 38.8%; P < .001). The HCV incidence density was 36.8 (95% confidence interval [CI], 24.2-53.5) per 100 person-years in youths reporting survival sex work involvement at baseline compared with 14.1 (9.4-20.3) per 100 person-years in youths not reporting survival sex work. In multivariate Cox proportional hazards analyses, survival sex work was the strongest predictor of elevated HCV incidence (adjusted relative hazard, 2.30; 95% CI, 1.27-4.15).
Conclusion
This study calls attention to the critical need for evidence-based social and structural HCV prevention efforts that target youths engaged in survival sex work.
doi:10.1001/archpediatrics.2009.241
PMCID: PMC4646708  PMID: 20048243
21.  COGNITIVE FACTORS AND WILLINGNESS TO PARTICIPATE IN AN HIV VACCINE TRIAL AMONG HIV-NEGATIVE INJECTION DRUG USERS 
Vaccine  2009;28(7):1663-1667.
This cross-sectional study involving a cohort of injection drug users (IDU) examined the relationship between cognitive factors (HIV treatment optimism, self-efficacy and knowledge of vaccine trial concepts) as well as risk factors for seroconversion, and willingness to participate (WTP) in a preventive phase 3 HIV vaccine trial. Willingness to participate overall was 56%. In a multivariate analysis, for a 20-unit increase in a 100-point composite scale, self-efficacy was positively related to WTP (adjusted odds ratio [AOR] = 1.95, 95% CI = 1.40–2.70). HIV treatment optimism and knowledge of vaccine trial concepts were unrelated to WTP. Aboriginal ethnicity (AOR = 3.47, 95% CI = 1.68–7.18) and a higher educational level (≥high school) (AOR = 1.96, 95% CI = 1.07–3.59) were positively related to WTP. This study provides information on WTP for an HIV vaccine trial. Limitations and future directions are also discussed.
doi:10.1016/j.vaccine.2009.12.023
PMCID: PMC4646221  PMID: 20044049
HIV vaccine preparedness; Cognitive factors; Injection drug users; VIDUS; Vancouver
22.  MODELLING CRACK COCAINE USE TRENDS OVER 10 YEARS IN A CANADIAN SETTING 
Drug and alcohol review  2010;29(3):271-277.
Introduction and Aims
Crack cocaine use among illicit drug users is associated with a range of health and community harms. However, long-term epidemiological data documenting patterns and risk factors for crack use initiation remain limited especially among injection drug users. We investigated longitudinal patterns of crack cocaine use among polydrug users in Vancouver, Canada.
Design and Methods
We examined the rate of crack use among injection drug users enrolled in a prospective cohort study in Vancouver, Canada between 1996 and 2005. We also used a Cox proportional hazards regression analysis to identify independent predictors of crack use initiation among this population.
Results
In total, 1603 injection drug users were recruited between May 1996 and December 2005. At baseline, 7.4% of participants reported ever using crack and this rate increased to 42.6% by the end of the study period (Mantel trend test P < 0.001).
Independent predictors of crack use initiation during the study period included frequent cocaine injection, crystal methamphetamine injection, residency in the city's drug using epicenter and involvement in the sex trade (all P < 0.05).
Discussion and Conclusions
These findings demonstrate a massive increase in crack use among injection drug users in a Canadian setting. Our findings also highlight the complex interactions that contribute to the initiation of crack use among injection drug users and suggest that evidence-based interventions are urgently needed to address crack use initiation and to address harms associated with its ongoing use.
doi:10.1111/j.1465-3362.2009.00145.x
PMCID: PMC4643832  PMID: 20565519
crack cocaine; injection drug use; initiation; Vancouver; predictive modelling
23.  FACTORS ASSOCIATED WITH EMPLOYMENT AMONG A COHORT OF INJECTION DRUG USERS 
Drug and alcohol review  2010;29(3):293-300.
Introduction and Aims
One of the most substantial costs of drug use is lost productivity and social functioning, including holding of a regular job. However, little is known about employment patterns of injection drug users (IDU). We sought to identify factors that were associated with legal employment among IDU.
Design and Methods
We describe the employment patterns of participants of a longitudinal cohort study of IDU in Vancouver, Canada. We then use generalised estimating equations (GEE) to determine statistical associations between legal employment and various intrinsic, acquired, behavioural and circumstantial factors.
Results
From 1 June 1999 to 30 November 2003, 330 (27.7%) of 1190 participants reported having a job at some point during follow up. Employment rates remain somewhat stable throughout the study period (9–12.4%). Factors positively and significantly associated with legal employment in multivariate analysis were male gender (adjusted odds ratio [AOR] = 2.78) and living outside the Downtown Eastside (AOR = 1.85). Factors negatively and significantly associated with legal employment included older age (AOR = 0.97); Aboriginal ethnicity (AOR = 0.72); HIV-positive serostatus (AOR = 0.32); HCV-positive serostatus (AOR = 0.46); daily heroin injection (AOR = 0.73); daily crack use (AOR = 0.77); public injecting (AOR = 0.50); sex trade involvement (AOR = 0.49); recent incarceration (AOR = 0.56); and unstable housing (AOR = 0.57).
Discussion and Conclusions
Our results suggest a stabilising effect of employment for IDU and socio-demographic, drug use and risk-related barriers to employment. There is a strong case to address these barriers and to develop innovative employment programming for high-risk drug users.
doi:10.1111/j.1465-3362.2009.00141.x
PMCID: PMC4638214  PMID: 20565522
employment; injection drug use; Vancouver
24.  USE OF A MEDICALLY SUPERVISED INJECTION FACILITY AMONG STREET YOUTH 
Purpose
Supervised injecting facilities (SIFs) provide a sanctioned space for injection drug users and are associated with decreased overdose mortality and HIV risk behaviors among adults. Little is known about SIF use among youth. We identified factors associated with use of the Vancouver SIF, the only such facility in North America, among street youth.
Methods
From September 2005 to May 2012, we collected data from the At-Risk Youth Study (ARYS), a prospective cohort of street youth in Vancouver, Canada. Eligible youth were aged 14–26 years. Participants reporting injection completed questionnaires at baseline and semiannually. We used generalized estimating equation logistic regression to identify factors associated with SIF use.
Results
During the study period, 42.3% of 414 injecting youth reported use of the SIF at least once. Of all SIF-using youth, 51.4% went to the facility at least weekly, and 44.5% used it for at least one-quarter of all injections. SIF-using youth were more likely to live or spend time in the neighborhood surrounding the SIF (adjusted odds ratio [AOR], 3.29; 95% confidence interval [CI], 2.38–4.54), to inject in public (AOR, 2.08; 95% CI, 1.53–2.84), or to engage in daily injection of heroin (AOR, 2.36; 95% CI, 1.72–3.24), cocaine (AOR, 2.44; 95% CI, 1.34–4.45), or crystal methamphetamine (AOR, 1.62; 95% CI, 1.13–2.31).
Conclusions
This study, the first examining SIF use among street youth in North America, demonstrated that the facility attracted high-frequency young drug users most at risk of blood-borne infection and overdose, and those that otherwise inject in public spaces.
doi:10.1016/j.jadohealth.2014.04.013
PMCID: PMC4209311  PMID: 24925493
drug abuse; adolescent; needle sharing; HIV; hepatitis C
25.  Factors Associated with Leaving Hospital against Medical Advice among People Who Use Illicit Drugs in Vancouver, Canada 
PLoS ONE  2015;10(10):e0141594.
Background
Leaving hospital against medical advice (AMA) is common among people who use illicit drugs (PWUD) and is associated with severe health-related harms and costs. However, little is known about the prevalence of and factors associated with leaving AMA among PWUD.
Methods
Data were collected through two Canadian prospective cohort studies involving PWUD between September 2005 and July 2011 and linked to a hospital admission/discharge database. Bivariable and multivariable generalized estimating equations were used to examine factors associated with leaving hospital AMA among PWUD who were hospitalized.
Results
Among 488 participants who experienced at least one hospitalization, 212 (43.4%) left the hospital AMA at least once during the study period. In multivariable analyses, factors positively and significantly associated with leaving hospital AMA included: unstable employment (AOR = 1.92; 95% confidence interval [CI]: 1.22–3.03); recent incarceration (AOR = 1.63; 95%CI: 1.07–2.49); ≥ daily heroin injection (AOR = 1.49; 95%CI: 1.05–2.11); and younger age per year younger (adjusted odds ratio [AOR] = 1.04; 95%CI: 1.02–1.06).
Conclusions
We found a substantial proportion of PWUD in this setting left hospital AMA and that various markers of risk and vulnerability were associated with this phenomenon. Our findings highlight the need to address substance abuse issues early following hospital admission. These findings further suggest a need to develop novel interventions to minimize PWUD leaving hospital prematurely.
doi:10.1371/journal.pone.0141594
PMCID: PMC4624845  PMID: 26509447

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