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.
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.
abscesses; cellulitis; emergency department; epidemiology; gender; health services; injection drug use
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.
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
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.
harm reduction; crack smoking; crack pipe access; Vancouver
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.
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.
child abuse; sexual; drug abuse; adolescent; cohort studies
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.
street youth; adolescents; injection; drug use; sex; HIV/AIDS
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.
For decades, Thailand has experienced high rates of illicit drug use and related harms. In response, the Thai government has relied on drug law enforcement to address this problem. Despite these efforts, high rates of drug use persist, and Thailand has been contending with an enduring epidemic of human immunodeficiency virus (HIV) among people who inject drugs (IDU).
In response to concerns regarding drug-related harm in Thailand and a lack of research focused on the experiences and needs of Thai IDU, the Mitsampan Community Research Project was launched in 2008. The project involved administering surveys capturing a range of behavioral and other data to community-recruited IDU in Bangkok in 2008 and 2009.
In total, 468 IDU in Bangkok were enrolled in the project. Results revealed high rates of midazolam injection, non-fatal overdose and incarceration. Syringe sharing remained widespread among this population, driven primarily by problems with access to syringes and methamphetamine injection. As well, reports of police abuse were common and found to be associated with high-risk behavior. Problems with access to evidence-based drug treatment and HIV prevention programs were also documented. Although compulsory drug detention centers are widely used in Thailand, data suggested that these centers have little impact on drug use behaviors among IDU in Bangkok.
The findings from this project highlight many ongoing health and social problems related to illicit drug use and drug policies in Bangkok. They also suggest that the emphasis on criminal justice approaches has resulted in human rights violations at the hands of police, and harms associated with compulsory drug detention and incarceration. Collectively, the findings indicate the urgent need for the implementation of evidence-based policies and programs in this setting.
Injection drug use; Drug law enforcement; Harm reduction; Community-based participatory research; Thailand
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.
employment; addiction treatment; methadone maintenance therapy; Vancouver; injection drug use
We sought to identify factors associated with harmful microinjecting practices in a longitudinal cohort of IDU.
Using data from the Vancouver Injection Drug Users Study (VIDUS) between January 2004 and December 2005, generalized estimating equations (GEE) logistic regression was performed to examine sociodemographic and behavioral factors associated with four harmful microinjecting practices (frequent rushed injecting, frequent syringe borrowing, frequently injecting with a used water capsule, frequently injecting alone).
In total, 620 participants were included in the present analysis. Our study included 251 (40.5%) women and 203 (32.7%) self-identified Aboriginal participants. The median age was 31.9 (interquartile range: 23.4–39.3). GEE analyses found that each harmful microinjecting practice was associated with a unique profile of sociodemographic and behavioral factors.
We observed high rates of harmful microinjecting practices among IDU. The present study describes the epidemiology of harmful microinjecting practices and points to the need for strategies that target higher risk individuals including the use of peer-driven programs and drug-specific approaches in an effort to promote safer injecting practices.
injection drug use; harmful; Vancouver; microinjecting practices
Assisted injection is common among people who inject drugs (IDU), and has been associated with elevated risk for HIV infection and overdose. However, this practice has not been explored in the Asian context, including in Thailand, where HIV prevalence among IDU remains high.
Using multivariate logistic regression, we examined the prevalence and correlates of assisted injecting among IDU participating in the Mitsampan Community Research Project in Bangkok. We also sought to identify reasons for engaging in assisted injecting and those who provide this form of assistance.
In total, 430 IDU participated in this study, including 376 (87.5%) who reported having ever required assistance injecting, and 81 (18.8%) who reported assisted injecting in the previous six months. In multivariate analyses, assisted injecting in the previous six months was independently and positively associated with being female (adjusted odds ratio [AOR] = 2.42; 95% confidence interval [CI]: 1.40 – 4.18), being a weekly heroin injector (AOR = 1.78; 95% CI: 0.99 – 3.20), syringe sharing (AOR = 2.08; 95% CI: 1.18 – 3.68) and soft-tissue infection (AOR = 3.51; 95% CI: 1.43 – 2.53). Having a longer injecting career (AOR = 0.96; 95% CI: 0.94 – 0.99) was negatively associated with assisted injecting. Primary reasons given for engaging in assisted injecting included being new to injecting and lacking knowledge on how to inject. The most common providers of assistance with injecting were close friends.
We found a high prevalence of assisted injecting among IDU in Bangkok, with females, frequent heroin injectors, those with shorter injecting careers being more likely to engage in this practice. Those who require help with the injecting process are more likely to share syringes, and have skin infections. These findings indicate the need for interventions focused on promoting safer and self-administered injections.
Injection drug use; Thailand; Assisted injection
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.
Exchanging sex for money, drugs, or other commodities for survival is associated with an array of HIV risks. We sought to determine if street-involved drug-using sexual minority youth are at greater risk for survival sex work and are more likely to engage in risk behaviors with clients.
We examined factors associated with survival sex work among participants enrolled in the At Risk Youth Study using logistic regression. Self-reported risk behaviors with clients were also examined.
Of 558 participants eligible for this analysis, 75 (13.4%) identified as a sexual minority and 63 (11.3%) reported survival sex work in the past 6 months. Sexual minority males (adjusted odds ratio = 16.1, P < .001) and sexual minority females (adjusted odds ratio = 6.87, P < 0.001) were at significantly greater risk for survival sex work. Sexual minority youth were more likely to report inconsistent condom use with clients (odds ratio = 4.30, P = 0.049) and reported a greater number of clients in the past 6 months (median = 14 vs. 3, P = 0.008).
Sexual minority street youth are not only more likely to engage in survival sex work but also demonstrate elevated HIV risk behavior. These findings suggest that harm reduction and HIV prevention programs for sexual minority youth who exchange sex are urgently required.
adolescent; HIV; LGBT; sex work; sexual minority; street youth
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.
AUDIT; PUBLIC HEALTH
Thailand has for years attempted to address illicit drug use through aggressive drug law enforcement. Despite accounts of widespread violence by police against people who inject drugs (IDU), the impact of police violence has not been well investigated. In the wake of an intensified police crackdown in 2011, we sought to identify the prevalence and correlates of experiencing police beating among IDU in Bangkok.
Community-recruited samples of IDU in Bangkok were surveyed between June 2009 and October 2011. Multivariate log-binomial regression was used to identify factors associated with reporting police beating.
In total, 639 unique IDU participated in this serial cross-sectional study, with 240 (37.6%) participants reporting that they had been beaten by police. In multivariate analyses, reports of police beating were associated with male gender (Adjusted Prevalence Ratio [APR] = 4.43), younger age (APR = 1.69), reporting barriers to accessing healthcare (APR = 1.23), and a history of incarceration (APR = 2.51), compulsory drug detention (APR = 1.22) and syringe sharing (APR = 1.44), and study enrolment in 2011 (APR = 1.27) (all p < 0.05). Participants most commonly reported police beating during the interrogation process.
A high proportion of IDU in Bangkok reported having been beaten by the police. Experiencing police beating was independently associated with various indicators of drug-related harm. These findings suggest that the over-reliance on enforcement-based approaches is contributing to police-perpetrated abuses and the perpetuation of the HIV risk behaviour among Thai IDU.
HIV/AIDS; Drug law enforcement; Injection drug use; Harm reduction; Thailand
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.
Addiction treatment; deterrence; drug law enforcement; drug policy; drug use patterns; incarceration; injection cessation; injection drug use
HIV-positive injection drug users (IDU) are known to be at risk for multiple medical problems that may necessitate emergency department (ED) use, however, the relative contribution of HIV disease versus injection-related complications have not been well described.
We examined factors associated with ED use among a prospective cohort of HIV-positive IDU in a Canadian setting.
We enrolled HIV-positive IDU into a community-recruited prospective cohort study. We modeled factors associated with the time to first ED visit using Cox regression to determine factors independently associated with ED use. In sub-analyses, we examined ED diagnoses and subsequent hospital admission rates.
Between December 5, 2005, and April 30, 2008, 428 HIV-positive IDU were enrolled, among whom the cumulative incidence of ED use was 63.7% (95% Confidence Interval [CI]: 59.1% – 68.3%) at 12 months after enrollment. Factors independently associated with time to first ED visit included: unstable housing (Hazard Ratio [HR] = 1.5, 95% CI: 1.1–2.0) and reporting being unable to obtain needed health care services (HR = 2.2, 95% CI: 1.2–4.1), whereas CD4 count and viral load were non-significant. Skin and soft tissue infections (SSTIs) accounted for the greatest proportion of ED visits (17%). Of the 2461 visits to the ED, 419 (17%) were admitted to hospital.
High rates of ED use were observed among HIV-positive IDU, a behavior that was predicted by unstable housing and limited access to primary care. Factors other than HIV infection appear to be driving ED use among this population in the post-HAART era.
Emergency Service; Injection Drug Use; HIV; Canada
Innovative health programs for injection drug users (IDUs), such as supervised injecting facilities (SIFs), are often preceded by evaluations of IDUs’ willingness to use the service. The validity of these surveys has not been fully evaluated. We sought to determine whether measures of willingness collected prior to the opening of a Canadian SIF accurately predicted subsequent use of the program.
Data were derived from a prospective cohort of IDUs. The sample size for this study was 640 IDUs. Using multivariate logistic regression, it was assessed if a history of reporting willingness to use the program, were it available, was associated with subsequent use. In sub-analysis restricted to individuals who had a history of reported willingness, we used multivariate longitudinal analysis to identify factors associated with not attending the SIF.
Among 442 IDUs, 72% of those who reported initial willingness to use a SIF later attended the program, and a prior willingness to use a SIF significantly predicted later attendance (adjusted odds ratio = 1.67). In sub-analyses restricted to those who had a history of reporting willingness to use the SIF, not using the program was predicted by not frequenting the neighborhood where the SIF was located.
Our findings indicate that reported willingness measures collected from IDUs regarding potential SIF program participation prior to its opening independently predicted later attendance even when variables that were likely determinants of willingness were adjusted for. These data suggest that willingness measures are reasonably valid tools for planning the delivery of health services among IDU populations.
injection drug use; supervised injection facilities; validity of willingness measures
Previous studies suggest that active drug use may compromise HIV treatment among HIV-positive injection drug users (IDU). However, little is known about the differential impacts of cocaine injection, heroin injection, and combined cocaine and heroin injection on plasma HIV-1 RNA suppression.
Data were derived from a longstanding open prospective cohort of HIV-positive IDU in Vancouver, Canada. Kaplan-Meier methods and Cox proportional hazards regression were used to examine the impacts of different drug use patterns on rates of plasma HIV-1 RNA suppression.
Between May 1996 and April 2008, 267 antiretroviral (ART) naïve participants were seen for a median follow-up duration of 50.6 months after initiating ART. The incidence density of HIV-1 RNA suppression was 65.2 (95%CI: 57.0–74.2) per 100 person-years. In Kaplan-Meier analyses, compared to those who abstained from injecting, individuals injecting heroin, cocaine, or combined heroin/cocaine at baseline were significantly less likely to achieve viral suppression (all p < 0.01). However, none of the drug use categories remained associated with a reduced rate of viral suppression when considered as time-updated variables (all p > 0.05).
Active injecting at the time of ART initiation was associated with lower plasma HIV-1 RNA suppression rates; however, there was no difference in suppression rates when drug use patterns were examined over time. These findings imply that adherence interventions for active injectors should optimally be applied at the time of ART initiation.
injection drug use; antiretroviral therapy; viral suppression
During the mid-1990s, Vancouver experienced a well characterized HIV outbreak among injection drug users (IDU) and many questioned how this could occur in the presence of a high volume needle exchange program (NEP). Specific concerns were fuelled by early research demonstrating that frequent needle exchange program attendees were more likely to be HIV positive than those who attended the NEP less frequently. Since then, some have misinterpreted this finding as evidence that NEPs are ineffective or potentially harmful. In light of continuing questions about the Vancouver HIV epidemic, we review 15 years of peer-reviewed research on Vancouver’s NEP to describe what has been learned through this work. Our review demonstrates that: 1) NEP attendance is not causally associated with HIV infection, 2) frequent attendees of Vancouver’s NEP have higher risk profiles which explain their increased risk of HIV seroconversion, and 3) a number of policy concerns, as well as the high prevalence of cocaine injecting contributed to the failure of the NEP to prevent the outbreak. Additionally, we highlight several improvements to Vancouver’s NEP that contributed to declines in syringe sharing and HIV incidence. Vancouver’s experience provides a number of important lessons regarding NEP. Keys to success include refocusing the NEP away from an emphasis on public order objectives by separating distribution and collection functions, removing syringe distribution limits and decentralizing and diversifying NEP services. Additionally, our review highlights the importance of context when implementing NEPs, as well as ongoing evaluation to identify factors that constrain or improve access to sterile syringes.
needle exchange programs; injection drug use; HIV/AIDS; policing; Vancouver
Release from prison is associated with a markedly increased risk of both fatal and non-fatal drug overdose, yet the risk factors for overdose in recently released prisoners are poorly understood. The aim of this study was to identify risk and protective factors for non-fatal overdose (NFOD) among a cohort of illicit drug users in Vancouver, Canada, according to recent incarceration.
Prospective cohort of 2515 community-recruited illicit drug users in Vancouver, Canada, followed from 1996 to 2010. We examined factors associated with NFOD in the past six months separately among those who did and did not also report incarceration in the last six months.
One third of participants (n=829, 33.0%) reported at least one recent NFOD. Among those recently incarcerated, risk factors independently and positively associated with NFOD included daily use of heroin, benzodiazepines, cocaine or methamphetamine, binge drug use, public injecting and previous NFOD. Older age, methadone maintenance treatment and HIV seropositivity were protective against NFOD. A similar set of risk factors was identified among those who had not been incarcerated recently.
Among this cohort, and irrespective of recent incarceration, NFOD was associated with a range of modifiable risk factors including more frequent and riskier patterns of drug use. Not all ex-prisoners are at equal risk of overdose and there remains an urgent need to develop and implement evidence-based preventive interventions, targeting those with modifiable risk factors in this high risk group.
Overdose; Ex-prisoners; Drug users
Expanding access to highly active antiretroviral therapy (HAART) has become an important approach to HIV prevention in recent years. Previous studies suggest that concomitant changes in risk behaviours may either help or hinder programs that use a Treatment as Prevention strategy.
We consider HIV-related risk behaviour as a social contagion in a deterministic compartmental model, which treats risk behaviour and HIV infection as linked processes, where acquiring risk behaviour is a prerequisite for contracting HIV. The equilibrium behaviour of the model is analysed to determine epidemic outcomes under conditions of expanding HAART coverage along with risk behaviours that change with HAART coverage. We determined the potential impact of changes in risk behaviour on the outcomes of Treatment as Prevention strategies. Model results show that HIV incidence and prevalence decline only above threshold levels of HAART coverage, which depends strongly on risk behaviour parameter values. Expanding HAART coverage with simultaneous reduction in risk behaviour act synergistically to accelerate the drop in HIV incidence and prevalence. Above the thresholds, additional HAART coverage is always sufficient to reverse the impact of HAART optimism on incidence and prevalence. Applying the model to an HIV epidemic in Vancouver, Canada, showed no evidence of HAART optimism in that setting.
Our results suggest that Treatment as Prevention has significant potential for controlling the HIV epidemic once HAART coverage reaches a threshold. Furthermore, expanding HAART coverage combined with interventions targeting risk behaviours amplify the preventive impact, potentially driving the HIV epidemic to elimination.
Previous studies of adherence to antiretroviral therapy (ART) for HIV among young injection drug users (IDU) have been limited because financial barriers to care disproportionately affect youth, thus confounding results. This study examines adherence among IDU in a unique setting where all medical care is provided free-of-charge. From May 1996 to April 2008, we followed a prospective cohort of 545 HIV-positive IDU of 18 years of age or older in Vancouver, Canada. Using generalized estimating equations (GEE), we studied the association between age and adherence (obtaining ART≥95% of the prescribed time), controlling for potential confounders. Using Cox proportional hazards regression, we also studied the effect of age on time to viral load suppression (<500 copies per milliliter), and examined adherence as a mediating variable. Five hundred forty-five participants were followed for a median of 23.8 months (interquartile range [IQR]=8.5–91.6 months). Odds of adherence were significantly lower among younger IDU (adjusted odds ratio [AOR]=0.76 per 10 years younger; 95% confidence interval [CI], 0.65–0.89). Younger IDU were also less likely to achieve viral load suppression (adjusted hazard ratio [AHR]=0.75 per 10 years younger; 95% CI, 0.64–0.88). Adding adherence to the model eliminated this association with age, supporting the role of adherence as a mediating variable. Despite absence of financial barriers, younger IDU remain less likely to adhere to ART, resulting in inferior viral load suppression. Interventions should carefully address the unique needs of young HIV-positive IDU.
Evidence is needed to improve HIV treatment outcomes for individuals who use injection drugs (IDU). Although studies have suggested higher rates of plasma viral load (PVL) rebound among IDU on antiretroviral therapy (ART), risk factors for rebound have not been thoroughly investigated.
We used data from a long-running community-recruited prospective cohort of IDU in Vancouver, Canada, linked to comprehensive ART and clinical monitoring records. Using proportional hazards methods, we modeled the time to confirmed PVL rebound above 1000 copies/mL among IDU on ART with sustained viral suppression, defined as two consecutive undetectable PVL measures.
Between 1996 and 2009, 277 individuals had sustained viral suppression. Over a median follow-up of 32 months, 125 participants (45.1%) experienced at least one episode of virologic failure for an incidence of 12.6 (95% Confidence Interval [CI]: 10.5 – 15.0) per 100 person years. In a multivariate model, PVL rebound was independently associated with sex trade involvement (Adjusted Hazard Ratio [AHR] = 1.40, 95% CI: 1.08 – 1.82) and recent incarceration (AHR = 1.83, 95% CI: 1.33 – 2.52). Methadone maintenance therapy (AHR = 0.79, 95% CI: 0.66 – 0.94) was protective. No measure of illicit drug use was predictive.
In this setting of free ART, several social and environmental factors predicted higher risks of viral rebound among IDU, including sex trade involvement and incarceration. These findings should help inform efforts to identify individuals at risk of viral rebound as well as targeted interventions to treat and retain individuals in effective ART.
human immunodeficiency virus (HIV) infection; antiretroviral therapy (ART); injection drug user (IDU); plasma HIV-1 RNA viral load; viral suppression; viral rebound