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1.  Homelessness Independently Predicts Injection Drug Use Initiation among Street-involved Youth in a Canadian setting 
This longitudinal study examines the association between homelessness and injection drug use initiation among a cohort of street-involved youth in a setting of high prevalence crystal methamphetamine use.
Data were derived from the At-Risk Youth Study, a prospective cohort of street-involved youth aged 14 to 26 recruited between September 2005 and November 2011. Cox proportional hazards regression was used to identify factors independently associated with time to injection initiation.
Among 422 street-youth who had never injected at baseline, 77 injection initiation events were observed during follow-up. Homelessness was independently associated with injection initiation in multivariate Cox regression (Relative Hazard: 1.80 [95% CI: 1.13–2.87]) after adjusting for crystal methamphetamine use and other potential confounders.
These findings highlight that homelessness is a key risk factor for injection initiation among street-involved youth. Supportive housing interventions for street-youth may help prevent injection drug use initiation among this high-risk population.
PMCID: PMC3608753  PMID: 23299006
Youth; injection drug use; initiation; homelessness
2.  Gender Inequities in Quality of Care among HIV-Positive Individuals Initiating Antiretroviral Treatment in British Columbia, Canada (2000–2010) 
PLoS ONE  2014;9(3):e92334.
We measured gender differences in “Quality of Care” (QOC) during the first year after initiation of antiretroviral therapy and investigated factors associated with poorer QOC among women.
QOC was estimated using the Programmatic Compliance Score (PCS), a validated metric associated with all-cause mortality, among all patients (≥19 years) who initiated ART in British Columbia, Canada (2000–2010).
PCS includes six indicators of non-compliance with treatment initiation guidelines at baseline (not having drug resistance testing before treatment; starting on a non-recommended regimen; starting therapy at CD4<200 cells/mm3) and during first-year follow-up (receiving <3 CD4 tests; receiving <3 viral load tests; not achieving viral suppression within six months). Summary scores range from 0–6; higher scores indicate poorer QOC. Multivariable ordinal logistic regression was used to measure if female gender was an independent predictor of poorer QOC and factors associated with poorer QOC among women.
QOC was determined for 3,642 patients (20% women). At baseline: 42% of women (34% men) did not have resistance testing before treatment; 17% of women (9% men) started on a non-recommended regimen (all p<0.001). At follow-up: 17% of women (11% men) received <3 CD4; 17% of women (11% men) received <3 VL; 50% of women (41% men) did not achieve viral suppression (all p<0.001). Overall, QOC was better among men (mean PSC = 1.54 (SD = 1.30)) compared with women (mean = 1.89 (SD = 1.37); p<0.001). In the multivariable model, female gender (AOR = 1.16 [95% CI: 0.99–1.35]; p = 0.062) remained associated with poorer QOC after covariate adjustment. Among women, those with injection drug use history, of Aboriginal ancestry, from Vancouver Island, and who initiated ART in earlier years were more likely to have poorer QOC.
Poorer QOC among women, especially from marginalized communities, demands that barriers undermining women's access to high-quality care be addressed to improve treatment and health for women with HIV.
PMCID: PMC3958538  PMID: 24642949
3.  Severe food insecurity is associated with elevated unprotected sex among HIV-seropositive injection drug users independent of HAART use 
AIDS (London, England)  2011;25(16):2037-2042.
Despite emerging evidence of a significant adverse relationship between food insecurity and sexual risk-taking, data have been primarily derived from resource-constrained settings and HIV-negative populations. To our knowledge, this study is the first to longitudinally evaluate the relationship between food insecurity and unprotected sex among HIV-seropositive people who inject drugs [injection drug users (IDUs)] both on and not on HAART.
Longitudinal analyses were restricted to HIV-positive IDUs who completed baseline and at least one follow-up visit in a prospective cohort (AIDS Care Cohort to evaluate Exposure to Survival Services, 2005–2009).
We constructed a multivariate logistic model using generalized estimating equations (GEEs) to assess an independent relationship between severe food insecurity (e.g., hunger due to lack of access or means to acquire food) and unprotected vaginal/anal sex.
Among 470 HIV-positive IDUs, the median age was 42 years (interquartile range 36–47) with 61% men and 39% women. The prevalence of severe food insecurity was 71%, with no differences by HAART use. Severe food insecure IDUs were marginally less likely to have a suppressed HIV-1 RNA viral load (31 vs. 39%, p=0.099). In multivariate GEE analyses, severe food insecurity [adjusted odds ratio=2.68, 95% confidence interval 1.49–4.82] remained independently correlated with unprotected sex among HIV-positive IDUs, controlling for age, sex/gender, married/cohabitating partner, binge drug use, homelessness, and HAART use.
These findings highlight a crucial need for structural HIV interventions that incorporate targeted food assistance strategies for IDUs. Given recent evidence of poor virological response among food insecure individuals on HAART, innovative HIV care models should integrate targeted food security programs and early access to HAART.
PMCID: PMC3956106  PMID: 21811140
food insecurity; HAART; HIV/AIDS; injection drug use; sexual risk
4.  Social and structural factors associated with HIV disease progression among illicit drug users: A systematic review 
AIDS (London, England)  2012;26(9):1049-1063.
To systematically review factors associated with HIV disease progression among illicit drug users, focusing on exposures exogenous to individuals that likely shape access and adherence to HIV treatment.
A systematic review of peer-reviewed English-language studies among HIV-seropositive illicit drug users with at least one of these endpoint of interest: a diagnosis of AIDS; death; changes/differences in CD4 cell counts; or changes/differences in plasma HIV-1 RNA levels.
Articles were included if they reported factors associated with an outcome of interest among a group of illicit drug users. Studies were identified, screened and selected using systematic methods.
Of 2,668 studies matching the search criteria, 58 (2%) met the inclusion criteria, all but one from North America or Western Europe. Overall, 41 (71%) studies contained significant individual-level clinical characteristics or behaviours (e.g., illicit drug use) associated with disease progression. Fifteen studies (26%) identified significant social, physical, economic or policy-level exposures, including incarceration, housing status or lack of legal income.
While past studies demonstrate important environmental exposures that appear to shape access to care and subsequent disease progression, the limited literature to examine these factors demonstrates the need for future research to consider risk environment characteristics and the role they may play in shaping health outcomes from HIV infection among drug users through determining access and adherence to evidence-based care. (198 words)
PMCID: PMC3955099  PMID: 22333747
Antiretroviral therapy; CD4; drug users; pathogenesis; progression; risk factors; viral load
5.  Expansion of HAART Coverage Is Associated with Sustained Decreases in HIV/AIDS Morbidity, Mortality and HIV Transmission: The “HIV Treatment as Prevention” Experience in a Canadian Setting 
PLoS ONE  2014;9(2):e87872.
There has been renewed call for the global expansion of highly active antiretroviral therapy (HAART) under the framework of HIV treatment as prevention (TasP). However, population-level sustainability of this strategy has not been characterized.
We used population-level longitudinal data from province-wide registries including plasma viral load, CD4 count, drug resistance, HAART use, HIV diagnoses, AIDS incidence, and HIV-related mortality. We fitted two Poisson regression models over the study period, to relate estimated HIV incidence and the number of individuals on HAART and the percentage of virologically suppressed individuals.
HAART coverage, median pre-HAART CD4 count, and HAART adherence increased over time and were associated with increasing virological suppression and decreasing drug resistance. AIDS incidence decreased from 6.9 to 1.4 per 100,000 population (80% decrease, p = 0.0330) and HIV-related mortality decreased from 6.5 to 1.3 per 100,000 population (80% decrease, p = 0.0115). New HIV diagnoses declined from 702 to 238 cases (66% decrease; p = 0.0004) with a consequent estimated decline in HIV incident cases from 632 to 368 cases per year (42% decrease; p = 0.0003). Finally, our models suggested that for each increase of 100 individuals on HAART, the estimated HIV incidence decreased 1.2% and for every 1% increase in the number of individuals suppressed on HAART, the estimated HIV incidence also decreased by 1%.
Our results show that HAART expansion between 1996 and 2012 in BC was associated with a sustained and profound population-level decrease in morbidity, mortality and HIV transmission. Our findings support the long-term effectiveness and sustainability of HIV treatment as prevention within an adequately resourced environment with no financial barriers to diagnosis, medical care or antiretroviral drugs. The 2013 Consolidated World Health Organization Antiretroviral Therapy Guidelines offer a unique opportunity to further evaluate TasP in other settings, particularly within generalized epidemics, and resource-limited setting, as advocated by UNAIDS.
PMCID: PMC3922718  PMID: 24533061
6.  Identifying self-perceived HIV-related stigma in a population accessing antiretroviral therapy 
AIDS care  2012;25(1):10.1080/09540121.2012.687809.
This study identifies factors associated with self-perceived HIV-related stigma (stigma) among a cohort of individuals accessing antiretroviral therapy (ART) in British Columbia, Canada. Data were drawn from the Longitudinal Investigations into Supportive and Ancillary Health Services study, which collects social, clinical, and quality of life (QoL) information through an interviewer-administered survey. Clinical variables (i.e. CD4 count) were obtained through linkages with the British Columbia HIV/AIDS Drug Treatment Program. Multivariable linear regression was performed to determine the independent predictors of stigma. Our results indicate that among participants with high school education or greater the outcome stigma, was associated with a 3.05 stigma unit decrease (95% CI: −5.16, −0.93). Having higher relative standard of living and perceiving greater neighborhood cohesion were also associated with a decrease in stigma (−5.30 95% CI: −8.16, −2.44; −0.80 95% CI: −1.39, −0.21, respectively). Lower levels of stigma were found to be associated with better QoL measures, including perceiving better overall function (−0.90 95% CI: −1.47, −0.34), having fewer health worries (−2.11 95% CI: −2.65, −1.57), having fewer financial worries (−0.67 95% CI: −1.12, −0.23), and having less HIV disclosure concerns (−4.12 95% CI: −4.63, −3.62). The results of this study show that participants with higher education level, better QoL measures, and higher self-reported standards of living are less likely to perceive HIV-related stigma.
PMCID: PMC3879041  PMID: 22672228
stigma; ART; quality of life; HIV
7.  Gender Differences in Clinical Outcomes among HIV-Positive Individuals on Antiretroviral Therapy in Canada: A Multisite Cohort Study 
PLoS ONE  2013;8(12):e83649.
Cohort data examining differences by gender in clinical responses to combination antiretroviral therapy (ART) remain inconsistent and have yet to be explored in a multi-province Canadian setting. This study investigates gender differences by injection drug use (IDU) history in virologic responses to ART and mortality.
Data from the Canadian Observational Cohort (CANOC) collaboration, a multisite cohort study of HIV-positive individuals initiating ART after January 1, 2000, were included. This analysis was restricted to participants with a follow-up HIV-RNA plasma viral load measure and known IDU history. Weibull hazard regression evaluated time to virologic suppression (2 consecutive measures <50 copies/mL), rebound (>1000 copies/mL after suppression), and all-cause mortality. Sensitivity analyses explored the impact of presumed ART use in pregnancy on virologic outcomes.
At baseline, women (1120 of 5442 participants) were younger (median 36 vs. 41 years) and more frequently reported IDU history (43.5% vs. 28.8%) (both p<0.001). Irrespective of IDU history, in adjusted multivariable analyses women were significantly less likely to virologically suppress after ART initiation and were at increased risk of viral load rebound. In adjusted time to death analysis, no differences by gender were noted. After adjusting for presumed ART use in pregnancy, observed gender differences in time to virologic suppression for non-IDU, and time to virologic rebound for IDU, became insignificant.
HIV-positive women in CANOC are at heightened risk for poor clinical outcomes. Further understanding of the intersections between gender and other factors augmenting risk is needed to maximize the benefits of ART.
PMCID: PMC3877405  PMID: 24391803
8.  Crystal methamphetamine and initiation of injection drug use among street-involved youth in a Canadian setting 
Although injection drug use is known to result in a range of health-related harms, including transmission of HIV and fatal overdose, little is known about the possible role of synthetic drugs in injection initiation. We sought to determine the effect of crystal methamphetamine use on risk of injection initiation among street-involved youth in a Canadian setting.
We used Cox regression analyses to identify predictors of injection initiation among injection-naive street-involved youth enrolled in the At-Risk Youth Study, a prospective cohort study of street-involved youth in Vancouver, British Columbia. Data on circumstances of first injection were also obtained.
Between October 2005 and November 2010, a total of 395 drug injection–naive, street-involved youth provided 1434 observations, with 64 (16.2%) participants initiating injection drug use during the follow-up period, for a cumulative incidence of 21.7 (95% confidence interval [CI] 1.7–41.7) per 100 person-years. In multivariable analysis, recent noninjection use of crystal methamphetamine was positively associated with subsequent injection initiation (adjusted hazard ratio 1.93, 95% CI 1.31–2.85). The drug of first injection was most commonly reported as crystal methamphetamine (14/31 [45%]).
Noninjection use of crystal methamphetamine predicted subsequent injection initiation, and crystal methamphetamine was the most commonly used drug at the time of first injection. Evidence-based strategies to prevent transition to injection drug use among crystal methamphetamine users are urgently needed.
PMCID: PMC3855114  PMID: 24130244
Cutaneous injection-related infections (CIRI) are a primary reason injection drug users (IDU) access the emergency department (ED).
Using Cox proportional hazard regression, we examined predictors of ED use for CIRI, stratified by sex, among 1083 supervised injection facility (SIF) users.
Over a four-year period, 289 (27%) visited the ED for CIRI, yielding an incidence density for females of 23.8 (95% confidence interval (CI): 19.3 – 29.0) and males of 19.2 per 100 person-years (95% CI: 16.7 – 22.1). Factors associated with ED use for CIRI among females included residing in the Downtown Eastside (DTES) (adjusted hazard ratio [AHR] = 2.06 [1.13 – 3.78]) and being referred to hospital by SIF nurses (AHR = 4.48 [2.76 – 7.30]). Among males, requiring assistance with injection (AHR = 1.38 [1.01 – 1.90]), being HIV-positive (AHR = 1.85 [1.34 – 2.55]), and being referred to hospital by SIF nurses (AHR = 2.97 [1.93 – 4.57]) were associated with an increased likelihood of an ED visit for CIRI.
These results suggest SIF nurses have facilitated referral of hospital treatment for CIRI, highlighting the need for continued development of efficient and collaborative efforts to reduce the burden of CIRI.
PMCID: PMC3856908  PMID: 24339842
abscesses; cellulitis; emergency department; epidemiology; gender; health services; injection drug use
10.  Housing Status and the Health of People Living with HIV/AIDS 
Current HIV/AIDS reports  2012;9(4):364-374.
Individuals who are homeless or living in marginal conditions have an elevated burden of infection with HIV. Existing research suggests the HIV/AIDS pandemic in resource-rich settings is increasingly concentrated among members of vulnerable and marginalized populations, including homeless/marginally-housed individuals, who have yet to benefit fully from recent advances in highly-active antiretroviral therapy (HAART). We reviewed the scientific evidence investigating the relationships between inferior housing and the health status, HAART access and adherence and HIV treatment outcomes of people living with HIV/AIDS (PLWHA.) Studies indicate being homeless/marginally-housed is common among PLWHA and associated with poorer levels of HAART access and sub-optimal treatment outcomes. Among homeless/marginally-housed PLWHA, determinants of poorer HAART access/adherence or treatment outcomes include depression, illicit drug use and medication insurance status. Future research should consider possible social- and structural-level determinants of HAART access and HV treatment outcomes that have been shown to increase vulnerability to HIV infection among homeless/marginally-housed individuals. As evidence indicates homeless/marginally-housed PLWHA with adequate levels of adherence can benefit from HAART at similar rates to housed PLWHA, and given the individual and community benefits of expanding HAART use, interventions to identify HIV-seropositive homeless/marginally-housed individuals and engage them in HIV care including comprehensive support for HAART adherence are urgently needed.
PMCID: PMC3693560  PMID: 22968432
HIV/AIDS; antiretroviral therapy; homelessness; People Living with HIV/AIDS (PLWHA); adherence; CD4+; plasma; HIV-1; RNA; viral load; highly-active antiretroviral therapy (HAART); behavior aspects of HIV/AIDS
11.  Incarceration is associated with used syringe lending among active injection drug users with detectable plasma HIV-1 RNA: a longitudinal analysis 
BMC Infectious Diseases  2013;13:565.
Informed by recent studies demonstrating the central role of plasma HIV-1 RNA viral load (VL) on HIV transmission, interventions to employ HIV antiretroviral treatment as prevention (TasP) are underway. To optimize these efforts, evidence is needed to identify factors associated with both non-suppressed VL and HIV risk behaviours. Thus, we sought to assess the possible role played by exposure to correctional facilities on VL non-suppression and used syringe lending among HIV-seropositive people who use injection drugs (PWID).
We used data from the ACCESS study, a community-recruited prospective cohort. We used longitudinal multivariate mixed-effects analyses to estimate the relationship between incarceration and plasma HIV-1 RNA > 500 copies/mL among antiretroviral therapy (ART)-exposed active PWID and, during periods of non-suppression, the relationship between incarceration and used syringe lending.
Between May 1996 and March 2012, 657 ART-exposed PWID were recruited. Incarceration was independently associated with higher odds of VL non-suppression (Adjusted Odds Ratio [AOR] = 1.54, 95% Confidence Interval [95% CI]: 1.10, 2.16). In a separate multivariate model restricted to periods of VL non-suppression, incarceration was independently associated with lending used syringes (AOR = 1.81, 95% CI: 1.03, 3.18).
The current findings demonstrate that incarceration is associated with used syringe lending among active PWID with detectable plasma HIV-1 RNA. Our results provide a possible pathway for the commonly observed association between incarceration and increased risk of HIV transmission. Our results suggest that alternatives to incarceration of non-violent PWID and evidence-based combination HIV prevention interventions for PWID within correctional facilities are urgently needed.
PMCID: PMC3924231  PMID: 24289651
12.  Antiretroviral Therapy Reduces HIV Transmission in Discordant Couples in Rural Yunnan, China 
PLoS ONE  2013;8(11):e77981.
Although HIV treatment as prevention (TasP) via early antiretroviral therapy (ART) has proven to reduce transmissions among HIV-serodiscordant couples, its full implementation in developing countries remains a challenge. In this study, we determine whether China's current HIV treatment program prevents new HIV infections among discordant couples in rural China.
A prospective, longitudinal cohort study was conducted from June 2009 to March 2011, in rural Yunnan. A total of 1,618 HIV-discordant couples were eligible, 1,101 were enrolled, and 813 were followed for an average of 1.4 person-years (PY). Routine ART was prescribed to HIV-positive spouses according to eligibility (CD4<350 cells/µl). Seroconversion was used to determine HIV incidence.
A total of 17 seroconversions were documented within 1,127 PY of follow-up, for an overall incidence of 1.5 per 100 PY. Epidemiological and genetic evidence confirmed that all 17 seroconverters were infected via marital secondary sexual transmission. Having an ART-experienced HIV-positive partner was associated with a lower rate of seroconvertion compared with having an ART-naïve HIV-positive partner (0.8 per 100 PY vs. 2.4 per 100 PY, HR = 0.34, 95%CI = 0.12–0.97, p = 0.0436). While we found that ART successfully suppressed plasma viral load to <400 copies/ml in the majority of cases (85.0% vs. 19.5%, p<0.0001 at baseline), we did document five seroconversions among ART-experienced subgroup.
ART is associated with a 66% reduction in HIV incidence among discordant couples in our sample, demonstrating the effectiveness of China's HIV treatment program at preventing new infections, and providing support for earlier ART initiation and TasP implementation in this region.
PMCID: PMC3827220  PMID: 24236010
13.  Personalized Risk Assessment of Drug-Related Harm Is Associated with Health Outcomes 
PLoS ONE  2013;8(11):e79754.
The Independent Scientific Committee on Drugs (ISCD) assigned quantitative scores for harm to 20 drugs. We hypothesized that a personalized, ISCD-based Composite Harm Score (CHS) would be associated with poor health outcomes in polysubstance users.
A prospective community sample (n=293) of adults living in marginal housing was assessed for substance use. The CHS was calculated based on the ISCD index, and the personal substance use characteristics over four weeks. Regression models estimated the association between CHS and physical, psychological, and social health outcomes.
Polysubstance use was pervasive (95.8%), as was multimorbid illness (median 3, possible range 0–12). The median CHS was 2845 (interquartile range 1865–3977). Adjusting for age and sex, every 1000-unit CHS increase was associated with greater mortality (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.07–2.01, p = 0.02), and persistent hepatitis C infection (OR 1.29, 95% CI 1.02–1.67, p = 0.04). The likelihood of substance-induced psychosis increased 1.39-fold (95% CI 1.13–1.67, p = 0.001). The amount spent on drugs increased 1.51-fold (1.40–1.62, p < 0.001) and the odds of having committed a crime increased 1.74-fold (1.46–2.10, p < 0.001). Multimorbid illness increased 1.43-fold (95% CI 1.26–1.63, p < 0.001).
Greater CHS predicts poorer physical, psychological, and social health, and may be a useful quantitative, personalized measure of risk for drug-related harm.
PMCID: PMC3819243  PMID: 24223192
14.  Factors associated with difficulty accessing crack cocaine pipes in a Canadian setting 
Drug and alcohol review  2012;31(7):890-896.
Crack cocaine pipe sharing is associated with various health-related harms, including hepatitis C transmission. Although difficulty accessing crack pipes has been found to predict pipe sharing, little is known about the factors that limit pipe access in settings where pipes are provided at no cost, albeit in limited capacity. Therefore, we investigated crack pipe access among people who use drugs in Vancouver, Canada.
Data was collected through two Canadian prospective cohort studies. Generalized estimating equations (GEE) with logit link for binary outcomes was used to identify factors associated with difficulty accessing crack pipes.
Among 914 participants who reported using crack cocaine, 33% reported difficulty accessing crack pipes. In multivariate analyses, factors independently associated with difficulty accessing crack pipes included: sex work involvement (adjusted odds ratio [AOR] = 1.57; 95% confidence interval [CI]: 1.03 – 2.39), having shared a crack pipe (AOR = 1.69; 95%CI: 1.32 – 2.16), police presence where one buys/uses drugs (AOR = 1.47; 95%CI: 1.10 – 1.95), difficulty accessing services (AOR = 1.74; 95%CI: 1.31 – 2.32), and health problems associated with crack use (AOR = 1.37; 95%CI: 1.04 – 1.79). Reasons given for difficulty accessing pipes included sources being closed (48.2%) and no one around selling pipes (18.1%).
A substantial proportion of people who smoke crack cocaine report difficulty accessing crack pipes in a setting where pipes are available at no cost but in limited quantity. These findings indicate the need for enhanced efforts to distribute crack pipes and address barriers to pipe access.
PMCID: PMC3389312  PMID: 22462808
harm reduction; crack smoking; crack pipe access; Vancouver
15.  Improved Adherence to Modern Antiretroviral Therapy among HIV Infected Injection Drug Users 
HIV medicine  2012;13(10):596-601.
Adherence to antiretroviral therapy (ART) among injection drug users (IDU) is often sub-optimal, yet little is known about changes in patterns of adherence since the advent of highly active antiretroviral therapy in 1996. We sought to assess levels of optimal adherence to ART among IDU in a setting of free and universal HIV care.
Data was collected through a prospective cohort study of HIV-positive IDU in Vancouver, British Columbia. We calculated the proportion of individuals achieving at least 95% adherence in the year following initiation of ART from 1996 to 2009.
Among 682 individuals who initiated ART, the median age was 37 (31–44) years with 248 (36.4%) female participants. The proportion achieving at least 95% adherence increased over time from 19.3% in 1996 to 65.9% in 2009 (Cochrane-Armitage test for trend: p < 0.001). In a logistic regression model examining factors associated with 95% adherence, initiation year was statistically significant (Odds Ratio = 1.08, 95% Confidence Interval: 1.03–1.13, p < 0.001 per year after 1996) after adjustment for a range of drug use variables and other potential confounders.
The proportion of IDU achieving at least 95% adherence during the first year of ART has consistently increased over a 13-year period. Although improved tolerability and convenience of modern ART regimens likely explain these positive trends, by the end of the study period a substantial proportion of IDU still had sub-optimal adherence demonstrating the need for additional adherence support strategies.
PMCID: PMC3414686  PMID: 22551168
16.  Childhood Sexual Abuse and Risk for Initiating Injection Drug Use: A Prospective Cohort Study 
Preventive medicine  2012;55(5):500-504.
This study examined whether childhood sexual abuse predicts initiation of injection drug use in a prospective cohort of youth.
From October 2005 to November 2010, data were collected from the At Risk Youth Study (ARYS), a prospective cohort study of street-involved youth in Vancouver, Canada. Inclusion criteria were age 14-26 years, no lifetime drug injection, and non-injection drug use in the month preceding enrollment. Participants were interviewed at baseline and semiannually thereafter. Cox regression was employed to identify risk factors for initiating injection.
Among 395 injection-naïve youth, 81 (20.5%) reported childhood sexual abuse. During a median follow-up of 15.9 months (total follow-up 606.6 person-years), 45 (11.4%) youth initiated injection drug use, resulting in an incidence density of 7.4 per 100 person-years. In univariate analyses, childhood sexual abuse was associated with increased risk of initiating injection (unadjusted hazard ratio [HR], 2.38; 95% confidence interval [CI], 1.29–4.38; p=0.006), an effect that persisted in multivariate analysis despite adjustment for gender, age, Aboriginal ancestry and recent non-injection drug use (adjusted HR, 2.71; 95% CI, 1.42–5.20; p=0.003).
Childhood sexual abuse places drug users at risk for initiating injection. Addiction treatment programs should incorporate services for survivors of childhood maltreatment.
PMCID: PMC3489963  PMID: 22954518
child abuse; sexual; drug abuse; adolescent; cohort studies
17.  Predictors of CD4:CD8 Ratio Normalization and Its Effect on Health Outcomes in the Era of Combination Antiretroviral Therapy 
PLoS ONE  2013;8(10):e77665.
HIV leads to CD4:CD8 ratio inversion as immune dysregulation progresses. We examined the predictors of CD4:CD8 normalization after combination antiretroviral therapy (cART) and determined whether normalization is associated with reduced progression to AIDS-defining illnesses (ADI) and death.
A Canadian cohort of HIV-positive adults with CD4:CD8<1.2 prior to starting cART from 2000–2010 were analyzed. Predictors of (1) reaching a CD4:CD8 ≥1.2 on two separate follow-up visits >30 days apart, and (2) ADI and death from all causes were assessed using adjusted proportional hazards models.
4206 patients were studied for a median of 2.77 years and 306 (7.2%) normalized their CD4:CD8 ratio. Factors associated with achieving a normal CD4:CD8 ratio were: baseline CD4+ T-cells >350 cells/mm3, baseline CD8+ T-cells <500 cells/mm3, time-updated HIV RNA suppression, and not reporting sex with other men as a risk factor. There were 213 ADIs and 214 deaths in 13476 person-years of follow-up. Achieving a normal CD4:CD8 ratio was not associated with time to ADI/death.
In our study, few individuals normalized their CD4:CD8 ratios within the first few years of initiating modern cART. This large study showed no additional short-term predictive value of the CD4:CD8 ratio for clinical outcomes after accounting for other risk factors including age and HIV RNA.
PMCID: PMC3813720  PMID: 24204912
18.  A comparison of drug use and risk behavior profiles among younger and older street youth 
Substance use & misuse  2011;46(12):1486-1494.
Among 559 street youth recruited between 2005 and 2007 in Vancouver, Canada, young drug users (<21years of age) were compared with older drug users (≥21 years) with regard to recent drug use and sexual practices using multiple logistic regression. Older youth were more likely to be male and of Aboriginal ancestry, to have more significant depressive symptoms, to have recently engaged in crack smoking, and to have had a recent history of injection drug use. Young drug users, by contrast, were more likely to have engaged in recent binge alcohol use. Efforts to reduce drug use-related harm among street youth may be improved by considering the highly prevalent use of “harder” drugs and risk for depression among older youth.
PMCID: PMC3799836  PMID: 21417557
street youth; adolescents; injection; drug use; sex; HIV/AIDS
19.  Use of North America’s first medically supervised safer injecting facility among HIV-positive injection drug users 
The objective of this study was to examine supervised injecting facility (SIF) use among a cohort of 395 HIV-positive injection drug users (IDUs) in Vancouver, Canada. The correlates of SIF use were identified using generalized estimating equation analyses. In multivariate analyses, frequent SIF use was associated with homelessness (adjusted odds ratio [AOR] = 1.90), daily heroin injection (AOR = 1.56), and daily cocaine injection (AOR = 1.59). The reasons given for not using the SIF included a preference for injecting at home and already having a safe place to inject. The SIF services most commonly used were needle exchange and nursing services. The SIF appears to have attracted a high-risk subpopulation of HIV-positive IDUs; this coverage perhaps could be extended with the addition of HIV- specific services such as disease monitoring and the provision of antiretroviral therapy.
PMCID: PMC3799861  PMID: 22010805
20.  Addiction treatment-related Employment barriers: the impact of methadone maintenance 
Employment is commonly upheld as an important outcome of addiction treatment. To explore this attribution we assessed whether treatment enrolment predicts employment initiation among participants enrolled in a community-recruited Canadian cohort of people who inject drugs (IDU) (n=1579). Survival analysis initially found no association between addiction treatment enrolment and employment initiation. However, when methadone maintenance therapy (MMT) was separated from other treatment modalities, non-MMT treatment positively predicted employment transitions, while MMT was negatively associated with employment initiation. Sub-analyses examining transitions into temporary, informal and under-the-table income generation echo these results. Findings suggest that individual factors impacting employment transitions may systematically apply to MMT clients, and that, in this setting, the impact of treatment on employment outcomes is contingent on treatment type and design. Treatment-specific differences underscore the need to expand low-threshold MMT, explore MMT alternatives and evaluate the impact of treatment design on the social and economic activity of IDU.
PMCID: PMC3345299  PMID: 22301085
employment; addiction treatment; methadone maintenance therapy; Vancouver; injection drug use
21.  Potential Impact of a Free Online HIV Treatment Response Prediction System for Reducing Virological Failures and Drug Costs after Antiretroviral Therapy Failure in a Resource-Limited Setting 
BioMed Research International  2013;2013:579741.
Objective. Antiretroviral drug selection in resource-limited settings is often dictated by strict protocols as part of a public health strategy. The objective of this retrospective study was to examine if the HIV-TRePS online treatment prediction tool could help reduce treatment failure and drug costs in such settings. Methods. The HIV-TRePS computational models were used to predict the probability of response to therapy for 206 cases of treatment change following failure in India. The models were used to identify alternative locally available 3-drug regimens, which were predicted to be effective. The costs of these regimens were compared to those actually used in the clinic. Results. The models predicted the responses to treatment of the cases with an accuracy of 0.64. The models identified alternative drug regimens that were predicted to result in improved virological response and lower costs than those used in the clinic in 85% of the cases. The average annual cost saving was $364 USD per year (41%). Conclusions. Computational models that do not require a genotype can predict and potentially avoid treatment failure and may reduce therapy costs. The use of such a system to guide therapeutic decision-making could confer health economic benefits in resource-limited settings.
PMCID: PMC3794568  PMID: 24175292
22.  Ready Access to Illicit Drugs among Youth and Adult Users 
Current drug-control strategies in Canada focus funding and resources predominantly on drug law enforcement, often at the expense of preventive, treatment, and harm reduction efforts. This study aimed to examine the availability of the most commonly used substances in Vancouver, Canada after the implementation of such strategies.
Using data from two large cohorts of drug-using youth and adults in Vancouver from the calendar year 2007, we assessed perceived availability of heroin, crack, cocaine, crystal methamphetamine, and marijuana.
Compared to youth (n = 330), a greater proportion of adults (n = 1160) reported immediate access (i.e., within ten minutes) to heroin (81.0% vs. 55.9%, p < 0.001), crack (90.4% vs. 69.3%, p < 0.001) and cocaine (83.7% vs. 61.1%, p < 0.001). Conversely, larger proportions of youth reported immediate access to crystal methamphetamine (62.8% vs. 39.4%, p < 0.001) and marijuana (88.4% vs. 73.2%, p < 0.001) compared to adult users.
Regardless of differences in illicit drug availability by age, all drugs are readily accessed in Vancouver despite drug law enforcement efforts. This includes drugs that are frequently injected and place users at risk of human immunodeficiency virus (HIV) infection and transmission of other blood-borne disease.
PMCID: PMC3419381  PMID: 22882400
23.  The temporal relationship between drug supply indicators: an audit of international government surveillance systems 
BMJ Open  2013;3(9):e003077.
Illegal drug use continues to be a major threat to community health and safety. We used international drug surveillance databases to assess the relationship between multiple long-term estimates of illegal drug price and purity.
We systematically searched for longitudinal measures of illegal drug supply indicators to assess the long-term impact of enforcement-based supply reduction interventions.
Data from identified illegal drug surveillance systems were analysed using an a priori defined protocol in which we sought to present annual estimates beginning in 1990. Data were then subjected to trend analyses.
Main outcome measures
Data were obtained from government surveillance systems assessing price, purity and/or seizure quantities of illegal drugs; systems with at least 10 years of longitudinal data assessing price, purity/potency or seizures were included.
We identified seven regional/international metasurveillance systems with longitudinal measures of price or purity/potency that met eligibility criteria. In the USA, the average inflation-adjusted and purity-adjusted prices of heroin, cocaine and cannabis decreased by 81%, 80% and 86%, respectively, between 1990 and 2007, whereas average purity increased by 60%, 11% and 161%, respectively. Similar trends were observed in Europe, where during the same period the average inflation-adjusted price of opiates and cocaine decreased by 74% and 51%, respectively. In Australia, the average inflation-adjusted price of cocaine decreased 14%, while the inflation-adjusted price of heroin and cannabis both decreased 49% between 2000 and 2010. During this time, seizures of these drugs in major production regions and major domestic markets generally increased.
With few exceptions and despite increasing investments in enforcement-based supply reduction efforts aimed at disrupting global drug supply, illegal drug prices have generally decreased while drug purity has generally increased since 1990. These findings suggest that expanding efforts at controlling the global illegal drug market through law enforcement are failing.
PMCID: PMC3787412  PMID: 24080093
24.  The association between food insecurity and mortality among HIV-infected individuals on HAART 
Food insecurity is increasingly recognized as a barrier to optimal treatment outcomes but there is little data on this issue. We assessed associations between food insecurity and mortality in HIV-infected antiretroviral therapy (ART)-treated individuals in Vancouver, British Columbia (BC), and whether body max index (BMI) modified associations.
Individuals were recruited from the BC HIV/AIDS drug treatment program in 1998 and 1999, and were followed until June 2007 for outcomes. Food insecurity was measured with the Radimer/Cornell questionnaire. Cox proportional hazard models were used to determine associations between food insecurity, BMI and non-accidental deaths when controlling for confounders.
Among 1119 participants, 536 (48%) were categorized as food insecure and 160 (14%) were categorized as underweight (BMI <18.5). After a median follow-up time of 8.2 years, 153 individuals (14%) had died from non-accidental deaths. After controlling for adherence, CD4 counts, and socioeconomic variables, people who were food insecure and underweight were nearly two times more likely to die (Adjusted hazard ratio [AHR]=1.94, 95% Confidence interval [CI]=1.10-3.40) compared with people who were not food insecure or underweight. There was also a trend towards increased risk of mortality among people who were food insecure and not underweight (AHR= 1.40, 95% CI=0.91-2.05). In contrast, people who were underweight but food secure were not more likely to die.
Food insecurity is a risk factor for mortality among ART-treated individuals in BC, particularly among individuals who are underweight. Innovative approaches to address food insecurity should be incorporated into HIV treatment programs.
PMCID: PMC3740738  PMID: 19675463
Food insecurity; HIV/AIDS; mortality; Vancouver
25.  Incarceration and drug use patterns among a cohort of injection drug users 
Addiction (Abingdon, England)  2009;104(1):69-76.
Drug law enforcement remains the dominant response to drug-related harm. However, the impact of incarceration on deterring drug use remains under-evaluated. We sought to explore the relationship between incarceration and patterns of drug use among people who inject drugs (IDU).
Using generalized estimating equations (GEE), we examined the prevalence and correlates of injection cessation among participants in the Vancouver Injection Drug User Study followed over 9 years. In subanalyses, we used McNemar's tests and linear growth curve analyses to assess changes in drug use patterns before and after a period of incarceration among participants reporting incarceration and those not incarcerated.
Among 1603 IDU, 842 (53%) reported injection cessation for at least 6 months at some point during follow-up. In multivariate GEE analyses, recent incarceration was associated negatively with injection cessation [adjusted odds ratio (AOR) = 0.43, 95% confidence interval (CI) 0.37–0.50], whereas the use of methadone was associated positively with cessation (AOR = 1.38, 95% CI 1.22–1.56). In subanalyses assessing longitudinal patterns of drug use among incarcerated individuals and those not incarcerated over the study period, linear growth curve analyses indicated that there were no statistically significant differences in patterns of drug use between the two groups (all P > 0.05).
These observational data suggest that incarceration does not reduce drug use among IDU. Incarceration may inhibit access to mechanisms that promote injection cessation among IDU. In contrast, results indicate that methadone use is associated positively with injection cessation, independent of previous frequency of drug use.
PMCID: PMC3731940  PMID: 19133890
Addiction treatment; deterrence; drug law enforcement; drug policy; drug use patterns; incarceration; injection cessation; injection drug use

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