Injection Drug Users In Vancouver Research Articles

Baseline self-perceived risk of HIV infection independently predicts the rate of HIV seroconversion in a prospective cohort of injection drug users

The identification of individuals at the highest risk of human immunodeficiency virus (HIV) infection is critical for targeting prevention strategies. We evaluated self-perceived risk of HIV infection and rates of subsequent HIV seroconversion among a prospective cohort study of injection drug users (IDUs). We performed an analysis of the time to HIV infection among 994 baseline HIV negative IDUs enrolled in the Vancouver injection drug users study (VIDUS). IDUs were stratified based on their baseline self-perceived risk of HIV seroconversion (higher than others vs same or lower). Kaplan-Meier methods were used to estimate cumulative HIV incidence rates and Cox regression was used to determine adjusted relative hazards for HIV seroconversion. At the end of 24 months after enrolment into the cohort, the cumulative HIV incidence rate was significantly elevated among the 5.9% of the sample who perceived their risk for HIV infection to be higher at baseline (26.6% vs 7.8% log-rank P < 0.001). In a Cox model that adjusted for all variables that were associated with the time to HIV infection in univariate analyses, a higher baseline self-perceived risk of acquiring HIV infection (relative hazard RH: 2.48 [95% Confidence interval (CI): 1.51, 4.10]; P = 0.004) remained independently associated with time to HIV seroconversion. IDUs' perception of their risk for HIV seroconversion upon enrolment into a prospective cohort study was strongly and independently associated with the subsequent rate of HIV seroconversion. Since this risk marker remained independently associated with HIV seroconversion, even after adjustment for time-updated risk behaviours, our findings have major implications that may aid outreach workers in their efforts to identify IDUs who should be targeted with prevention efforts.

Displacement of Canada's largest public illicit drug market in response to a police crackdown.

Law enforcement is often used in an effort to reduce the social, community and health-related harms of illicit drug use by injection drug users (IDUs). There are, however, few data on the benefits of such enforcement or on the potential harms. A large-scale police "crackdown" to control illicit drug use in Vancouver's Downtown Eastside provided us with an opportunity to evaluate the effect. As part of our ongoing prospective cohort study of IDUs in Vancouver, we examined data collected from 244 IDUs in the 3 months before the police crackdown and from 142 IDUs in the 3 months after the start of the crackdown, on Apr. 7, 2003. All study subjects were active drug users. We also examined external data on needle exchanges and syringe disposal. The 2 groups of IDUs were statistically similar: they were mainly young (mean age 39 years) and male (63%), and they had injected illicit drugs for 13 years on average. Ethnic background and the proportion homeless were also similar. There were no statistically significant reported differences (all p > 0.1) in the street price of heroin, cocaine or "crack" in the 2 periods. In the 3-month periods before and after the crackdown, respectively, the rates of daily heroin injection were 27.9% and 26.8%, daily cocaine injection 28.7% and 27.5%, and daily crack use 59.4% and 60.6% (all p > 0.1). The proportions of study subjects receiving methadone treatment, 41.0% and 44.4% (p = 0.516), did not differ. However, the proportions reporting a change in where drugs were used, 22.5% and 33.8% (p < 0.05), and the proportions reporting a change in the neighbourhood of use because of police presence, 18.1% and 26.8% (p < 0.05), increased significantly. Needle-exchange data confirmed that the community levels of drug use were unchanged. Disposal statistics demonstrated that the monthly average number of used syringes found on the streets outside the traditional area of drug use increased from 784 in the 3 months before Apr. 1 to 1253 in the subsequent 3 months (p = 0.002) and the monthly average number of used syringes found in public boxes for the safe disposal of syringes decreased from 865 to 502 (p = 0.018). The effort to control illicit drug use did not alter the price of drugs or the frequency of use, nor did it encourage enrollment in methadone treatment programs. Several measures indicated displacement of injection drug use from the area of the crackdown into adjacent areas of the city, which has implications for both recruitment of new initiates into injection drug use and HIV prevention efforts.

Alcohol use and incarceration adversely affect HIV-1 RNA suppression among injection drug users starting antiretroviral therapy.

We conducted this study among HIV-infected injection drug users to determine the effect of self-reported alcohol use and prior incarceration at the time of initiating antiretroviral therapy on subsequent HIV-1 RNA suppression. We examined the demographics, recent incarceration history, and drug and alcohol use history from the Vancouver Injection Drug User Study (VIDUS) questionnaire closest to the date of initiating antiretroviral therapy. We linked these data to the HIV/AIDS Drug Treatment Program. There were 234 VIDUS participants who accessed antiretroviral therapy through the Drug Treatment Program from August 1, 1996, to July 31, 2001. In terms of illicit drug use, 196 (84%) reported injecting heroin and cocaine at the time of initiating antiretroviral therapy. Multiple logistic regression revealed that in the 6 months prior to initiating antiretroviral therapy, alcohol use (adjusted odds ratio [AOR] 0.32; 95% CI 0.13-0.81) and incarceration (AOR 0.22; 95% CI 0.09-0.58) were independently associated with lower odds of HIV-1 RNA suppression. Factors positively associated with HIV-1 RNA suppression included: adherence (AOR 1.27; 95% CI 1.06-1.51); lower baseline HIV-1 RNA (AOR 1.30; 95% CI 1.01-1.66); highly active antiretroviral therapy (AOR 4.10; 95% CI 1.56-10.6); months on therapy (AOR 1.1; 95% CI 1.06-1.14). Among HIV-infected injection drug users who were on antiretroviral therapy, any alcohol use and incarceration in the 6 months prior to initiating antiretroviral therapy were negatively associated with achieving HIV-1 RNA suppression. In addition to addiction treatment for active heroin and cocaine use, the identification and treatment of alcohol problems should be supported in this setting. As well, increased outreach to HIV-infected drug users recently released from prison to ensure continuity of care needs to be further developed.

An external evaluation of a peer-run "unsanctioned" syringe exchange program.

In Vancouver, British Columbia, Canada, difficulty accessing syringes at night has been shown to be strongly associated with human immunodeficiency virus (HIV) risk behavior among the city's injection drug users (IDUs). On September 1, 2001, the Vancouver Area Network of Drug Users (VANDU) initiated an unsanctioned all-night needle-exchange program on a street corner in the heart of the neighborhood where many of the city's IDUs are concentrated. An external evaluation of the population reached by the VANDU exchange was performed through the Vancouver Injection Drug User's Study, a prospective cohort study of IDUs begun in 1996. Persons accessing syringes through the exchange were compared to those active injectors who acquired their syringes from other sources, including the city's fixed site exchange, which closes at 8:00 PM. Overall, 587 active IDUs were seen during the period September 2001 to June 2002; of these individuals, 165 (28.1%) reported using the VANDU exchange. In multivariate analyses, participants who used the VANDU table were more likely to frequently inject cocaine (adjusted odds ratio [AOR]=1.56; 95% confidence interval [CI]=1.00-2.44), inject in public (AOR=2.71; 95% CI=1.62-4.53), and require help injecting (OR=2.13; 95% CI=1.33-3.42). Interestingly, use of the table was also independently associated with safer syringe disposal (AOR=2.69; 95% CI=1.38-5.21). Results indicate that the unsanctioned exchange appears to have reached those IDUs at highest risk of HIV infection. Although the cross-sectional nature of the study design warrants caution, we also found that use of the nighttime exchange was strongly associated with higher rates of safe syringe disposal. The data suggest that drug user organizations can play a major role in reducing harm among their peers by reaching the highest risk drug users with harm reduction services. The findings also suggest that other forms of syringe-exchange programs should consider the benefits of offering fixed site nighttime service.

Requiring Help Injecting as a Risk Factor for HIV Infection in the Vancouver Epidemic

Requiring help injecting was recently associated with syringe sharing, and later HIV-1 and HCV seroconversion among injection drug users (IDU) in Vancouver. This risk factor remains poorly understood. The present study investigates this risk factor among Vancouver IDUs.We evaluated factors associated with requiring help injecting among participants enrolled in the Vancouver Injection Drug User Study (VIDUS) using univariate and logistic regression analyses. VIDUS participants who were followed-up during the period December 2000 to December 2001 were eligible for the present analyses. We also evaluated self-reported reasons for requiring help injecting.Overall, 661 active injection drug users were interviewed during the study period. Among this population, 151 (22.8%) had required help injecting during the last six months, whereas 510 (77.2%) indicated that they had not. Variables that were independently associated with requiring help injecting included borrowing a used syringe (adjusted odds ratio [AOR] = 2.18), frequent cocaine injection (AOR = 1.57), and female gender (AOR = 2.29). Among males, the most common reasons for requiring help injecting were: having no viable veins (77.1%), and anxiousness or being drug sick (42.9%). Among females, the most common reasons reported were: having no viable veins (71.6%), jugular injection or 'jugging' (45.7%), and being anxious or drug sick (27.2%). Almost twice as many females (13.6% vs 7.1%) reported not knowing how to inject as their reason for requiring help injecting.Although current public health approaches, such as needle exchange, are unable to address the concerns associated with requiring help injecting, available evidence suggests that safer injecting facilities have the potential to substantially mitigate this risk behaviour.

Psychosocial Determinants of Adherence to Highly Active Antiretroviral Therapy among Injection Drug Users in Vancouver

Sub-optimal adherence to highly active antiretroviral therapy (HAART) among injection drug users (IDUs) is a significant concern. As such, there is an urgent need to identify psychosocial determinants of adherence that can be incorporated into interventions designed to promote optimal adherence. To identify psychosocial determinants of adherence to HAART, as well as self-reported reasons for missing doses of HAART among HIV-infected IDUs. We developed an eight-item adherence self-efficacy scale comprised of two sub-scales: adherence efficacy and self-regulatory efficacy. We examined correlates between adherence self-efficacy, outcome expectations, socio-demographic characteristics, drug use and risk behaviours, social support and HAART adherence among 108 HIV-infected participants in the Vancouver Injection Drug Users Study (VIDUS). Pharmacy-based adherence to HAART was obtained through a confidential record linkage to the province of British Columbia's HIV/AIDS Drug Treatment Program. Participants were defined as adherent if they picked-up 95% of their HAART prescriptions. Participants were also asked to indicate reasons for missing doses of HAART. Logistic regression was used to identify the factors independently associated with adherence to HAART. Seventy-one (66%) HIV-infected IDUs were less than 95% adherent. Forgetting was the most frequently cited reason (27%) for missing doses of HAART. Factors independently associated with adherence to HAART included adherence efficacy expectations [OR=1.8 (95% CI: 1.0-3.1); P=0.039] and negative outcome expectations [OR=0.8 (95% CI: 0.7-0.9); P=0.027]. We found low rates of adherence to HAART among IDUs. Psychological constructs derived from self-efficacy theory are highly germane to the understanding of adherence behaviour, and interventions that address these constructs should be developed and tested among HIV-infected drug users.

High pregnancy rates and reproductive health indicators among female injection-drug users in Vancouver, Canada

High pregnancy rates and reproductive health indicators among female injection-drug users in Vancouver, Canada

Sexual violence among a cohort of injection drug users

The objective of this study was to determine the prevalence of, and factors associated with, sexual violence in childhood, adolescence and adulthood, among injection drug using men and women. The Vancouver Injection Drug User Study is a prospective cohort of injection drug users (IDU) begun in 1996. The analysis included all individuals who completed the baseline questionnaire who responded to a question about sexual assault. Multivariate modeling was used to determine and to what extent a history of sexual violence at different ages is predictive of HIV risk and other health risk behaviors. HIV prevalence was calculated as the total current number of HIV-positive individuals in the cohort. Of the 1437 eligible individuals, 36% reported a lifetime history of sexual violence; 68% of women, and 19% of men ( p<0.001). After adjusting for fixed sociodemographics, these individuals were more likely to have ever been in the sex trade, to knowingly share needles/rigs with HIV-positive people, to have attempted suicide, to have ever accidentally overdosed, to binge on alcohol, and to have been diagnosed with a mental disorder/disability. The prevalence of child sexual abuse in this cohort is 21%; 33% for women, and 13% for men. The data show a dose–response relationship between age at first sexual violence and most risk behaviors examined. These relationships are further mediated by gender. The prevalence of HIV among individuals who ever experienced sexual violence was 25%, compared to 19% among those who never experienced sexual violence ( p=0.006). Sexual violence, and especially child sexual abuse, is highly prevalent among this cohort, particularly among women. Child sexual abuse has worse consequences for both genders than sexual violence later in life. Nevertheless, women and men are affected differently by sexual violence at different ages, and this has significant implications for health promotion programs, and specifically HIV prevention.

High pregnancy rates and reproductive health indicators among female injection-drug users in Vancouver, Canada

Objective: To determine the incidence of pregnancy among active injection-drug users and to identify factors associated with becoming pregnant.Methods: The Vancouver Injection Drug UserStudy (VIDUS) is a prospective cohort study that began in 1996. Women who had completed a baseline and at least one follow-up questionnaire between June 1996 and January 2002 were included in the study.Parametric and non-parametric methods were used to compare characteristics of women who reported pregnancy over the study period with those who did not over the same time period.Results: A totalof 104 women reported a primary pregnancy over the study period. The incidence of pregnancy over the follow-up period was 6.46 (95% confidence interval (CI) 5.24-7.87) per 100 person-years. The averageage of women who reported pregnancy was younger than that of women who did not report pregnancy (27 vs. 32 years, p < 0.001). Women of Aboriginal ethnicity were more likely to report pregnancy(odds ratio 1.6, 95% CI 1.0-2.5). Comparison of drug use showed no significant differences in pregnancy rate with respect to the use of heroin, cocaine or crack (p > 0.05). In examining sexualbehavior, women who reported having had a regular partner in the previous 6 months were three times more likely to have reported pregnancy. Despite the fact that 67% of women in this study reported usingsome form of contraception, the use of reliable birth control was low. Only 5% of women in our study reported the use of hormonal contraceptives.Conclusion: There were a high number of pregnanciesamong high-risk women in this cohort. This corresponded with very low uptake of reliable contraception. Innovative strategies to provide reproductive health services to at-risk women who are injecting drugsis a public health priority.

The potential public health and community impacts of safer injecting facilities: evidence from a cohort of injection drug users.

Although medically supervised safer injecting facilities (SIFs) remain untested in North America, their implementation is currently being debated. Reluctance of health policy makers to initiate a pilot study of SIFs may in part be hindered by outstanding questions regarding the potential community and public health impact of the intervention. Specifically, it is presently unknown if those at greatest risk of overdose and HIV transmission or those responsible for community impact of injection drug use will be willing to attend. The current study was conducted to evaluate the proportion of injection drug users (IDU) willing to attend medically supervised SIFs, if they were available, among participants enrolled in the Vancouver Injection Drug User Study (VIDUS). The authors also evaluated factors associated with willingness to use a SIF using univariate and logistic regression analyses. Participants who were followed from June 2001 to June 2002 were eligible for the present analyses. Overall, 587 active IDU responded to a questionnaire during the study period. Among respondents, 215 (36.6%) expressed willingness to attend a SIF. Variables that were independently associated with willingness to attend a SIF in multivariate analyses included having difficulty accessing sterile syringes (adjusted odds ratio [AOR] = 2.07), requiring help injecting (AOR = 1.52), frequently injecting heroin (AOR = 1.81), sex trade work (AOR = 2.02), and injecting in public spaces (AOR = 2.00). Several variables that have recently been associated with overdose, syringe sharing, HIV and HCV incidence, and community impact of illicit drug use in this setting were associated with willingness to attend medically supervised SIFs. Although the impact of SIFs in North America can only be quantified by scientific evaluation, these data indicate a high potential for immediate community and public health benefits if SIFs were presently available.

Satellite needle distribution among injection drug users: policy and practice in two canadian cities.

Access to clean needles and syringes through needle exchange programs (NEPs) has reduced both high-risk behaviors and the transmission of blood-borne infections among injection drug users (IDUs). However, policies regarding "needle-for-needle" exchange versus unrestricted needle distribution remain controversial. The objective of this study was to compare sources of needles, trends in needle distribution, and the practice of satellite needle distribution (SND) among IDUs in Vancouver and Montreal. SND was defined as receiving a new syringe from another individual through trading, purchasing, borrowing, or being given the syringe outright, or supplying a syringe to another individual through trading, selling, lending, or giving a syringe outright. This was practiced by 46% of IDUs in Vancouver and 50% of IDUs in Montreal. SND was associated with borrowing used injection equipment (adjusted OR [AOR], 2.62; 95% CI: 1.85-3.71), conducting bulk needle exchanges (AOR, 1.85; 95% CI: 1.34-2.54), being married or in a common-law relationship (AOR, 1.85; 95% CI: 1.34-2.54), and regular visits to the NEP (> weekly) (AOR, 1.54; 95% CI: 1.17-2.13). In Vancouver, SND was also associated with borrowing used needles (AOR, 2.07; 95% CI: 1.22-3.52). In these two cities, despite different distribution policies, almost half of the participants reported SND, and this was associated with high risk sharing. The practice of SND appears to be an important mechanism for needle acquisition, especially for those at highest risk for HIV and hepatitis C transmission.

Science, Ideology, and Needle Exchange Programs

Needle exchange programs (NEPs) to prevent HIV transmission among injection drug users are accepted in many countries but remain at the center of heated debate in the United States. In 1997, the author published a study of injection drug users in Vancouver showing an explosive outbreak of HIV. An incidental finding was higher HIV rates among frequent attendees of the local NEP. While this was expected because NEPs attract users at highest risk, opponents of needle exchange applied an unsupportable causal interpretation to this finding. If frequent NEP attendees had higher HIV rates, so the interpretation went, NEPs must be responsible for promoting the spread of HIV. Despite the author's admonitions against this misinterpretation of the data, it was used as part of a successful campaign to oppose U.S. federal funding of needle exchange. Regrettably, biased or even misleading interpretations often occur in the volatile interface of imperfect science and ideological debate.

Factors associated with persistent high-risk syringe sharing in the presence of an established needle exchange programme.

Vancouver has experienced an explosive HIV epidemic despite the presence of a needle exchange programme (NEP). We sought possible explanations for high-risk syringe sharing among Vancouver injection drug users over the period January 1999 to October 2000. Overall, 14% of participants reported high-risk sharing. Although acquiring needles exclusively from the NEP was independently associated with less sharing, we identified several risk factors for persistent sharing, including difficulty accessing sterile needles, bingeing, and frequent cocaine injection.

High Pregnancy Rates and Reproductive Health Indicators among Female Injection Drug Users in Vancouver, Canada

High Pregnancy Rates and Reproductive Health Indicators among Female Injection Drug Users in Vancouver, Canada

Is early discharge safe after naloxone reversal of presumed opioid overdose?

Patients with suspected opioid overdose frequently require naloxone treatment. Despite recommendations to observe such patients for 4 to 24 hours after naloxone, earlier discharge is becoming more common. This prospective, observational study of patients with presumed opioid overdose examines the safety of early disposition decisions and the accuracy of outcome prediction by physicians 1 hour after the administration of naloxone. The study was carried out at St. Paul's Hospital, an inner city teaching centre that cares for most of the injection drug users in Vancouver, BC. Patients were formally assessed 1 hour after receiving naloxone for presumed opioid overdose. Demographics, medical history and physical examination were documented on specific data forms, and physicians recorded their comfort with early discharge. Patients were followed up, and those who required a critical intervention or suffered a pre-defined adverse event (AE) within 24 hours of their 1-hour assessment were identified. Of 573 patients, 48% were discharged in less than 2 hours, 23% in 2-4 hours and 29% in >4 hours. 94 patients who were held in the emergency department (ED) or admitted required a critical intervention, including supplemental oxygen for hypoxia (74), repeat naloxone (52), antibiotics administered intravenously (IV) (14), assisted ventilations (13), fluid bolus for hypotension (12), charcoal for associated life-threatening overdose (6), IV inotropic agents (2), antiarrhythmics for sustained tachycardia >130 beats/min (1), and administration of bicarbonate for arterial [HCO3] <5 or venous CO2 <5 (1). Physicians predicted adverse events with 94% sensitivity and 59% specificity. No discharged patients suffered a serious AE within 24 hours of ED discharge. Emergency physicians can clinically identify patients at risk of deterioration after naloxone reversal of suspected opioid overdose. Prolonged observation or hospital admission is not usually required. Selective early discharge of patients with presumed opioid overdose is feasible and appears safe. A clinical prediction rule may be useful in identifying patients eligible for early discharge.

Antiretroviral medication use among injection drug users: two potential futures.

To model the potential impact of HIV infection rates and the use of antiretroviral medication on life expectancy and mortality in the Downtown Eastside of Vancouver, British Columbia, Canada, from 1999 to 2006. Population projections were made to estimate the population of the Downtown Eastside in the year 2006. Two scenarios were modelled to predict the impact of HIV infection and antiretroviral use on mortality and life expectancy. The use of antiretroviral therapy was estimated to be 80% in the first scenario and 20% in the second. The prevalence of HIV by age and sex, and by year infected was estimated using data from the Vancouver Injection Drug User Study. If the level of antiretroviral therapy use among HIV-positive individuals was 80% at baseline, then we estimate that the life expectancy at birth in the year 2006 will be 60.8 years for men and 72.8 years for women, and 172 AIDS deaths will occur between 1999 and 2006. In contrast, if the present level of antiretroviral medication use persists, the life expectancy at birth in the year 2006 will be 56.9 years for men and 68.6 years for women, and 503 AIDS deaths will occur between 1999 and 2006. Our analysis suggests that if the low levels of antiretroviral therapy use persist, life expectancy in Vancouver's Downtown Eastside will soon be on a par with many of the world's least developed countries. Our findings highlight the large health status decline that can be expected in many inner city neighbourhoods if low levels of antiretroviral use persist. Although reasonable coverage targets for injection drug users (IDU) have not been established, the expanded use of antiretroviral medication is urgently needed to avert a drastic decline in health status.

A qualitative investigation into an HIV outbreak among injection drug users in Vancouver, British Columbia

The proportion of injection drug users (IDUs) testing positive for Human Immunodeficiency Virus (HIV) in British Columbia has increased from 3 to 7% since January 1993 (Patrick et al ., 1997). We conducted a qualitative study as a first step in a case control investigation aimed at identifying risk factors associated with HIV seroconversion. Sixteen subjects participated in in-depth interviews which were transcribed and analysed using grounded theory methods. Three dominant themes emerged: Addiction, Prevention, and Social Determinants. The results suggest that prevention efforts such as the availability of clean needles and condoms are not adequate to combat the complex social determinants of addiction-be they causal or consequential-which in turn contribute to unsafe injection practices.

Injection drug use and HIV infection among the seriously mentally ill: a report from Vancouver.

A recently reported outbreak of HIV among injection drug users in Vancouver determined that, in early 1997, 23% of this population was HIV-positive, and that HIV-negative injection drug users were becoming positive at the rate of 18.6% per year, the highest rate reported in North America. One significant factor behind the outbreak is the high prevalence of injection cocaine use among drug addicts in Vancouver. Cocaine, because it has a short "high," creates a need for more frequent injections and therefore increases the likelihood of needle sharing and HIV transmission. The mentally ill in Vancouver are particularly at risk for HIV infection because of their vulnerability to substance misuse and because large numbers of them reside in the main drug-using neighborhood. The provincial and federal governments have made $4,700,000 available to respond to this public health emergency, to be spent on the expansion of community services, including a number of needle-exchange sites. Accessing these and other health care services continues to be a challenge for injection drug users who also suffer from serious mental illnesses; for these persons an assertive case management model may be the most effective way of maintaining continuity of care.

Factors associated with frequent needle exchange program attendance in injection drug users in Vancouver, Canada.

The objective of this study was to identify factors associated with frequent needle exchange program (NEP) attendance by injection drug users (IDUs) in Vancouver, Canada. Data were examined from a case control study of recent HIV infection. IDUs with documented HIV seroconversion after January 1, 1994 (n = 89) and seronegative controls with two documented HIV-negative test results in the same period (n = 192) were asked about demographic and social information, drug injection and sexual behavior, and NEP attendance. Logistic regression was used to examine the effect of multiple variables on NEP attendance while adjusting for HIV status and other potential confounders. Frequent (> 1 time/week) versus nonfrequent (< or = 1 time/week) NEP attenders did not differ with respect to gender, age, ethnicity, education, or HIV serostatus. For men, multivariate analysis showed that frequent cocaine injection was the only variable independently associated with NEP attendance (adjusted odds ratio [AOR] = 3.9; 95% confidence interval [CI] = 1.8-8.3); for women, independently associated variables were frequency of any drug injection (AOR = 5.5; 95% CI = 1.7-17), shooting gallery attendance (AOR = 11.5; 95% CI = 2.2-66), and having a nonlegal source of income (AOR = 3.4; 95% CI = 1.0-12). Borrowing used needles was associated with frequent NEP attendance in the univariate analysis. The NEP in Vancouver attracts IDUs who are frequent injectors (especially men using cocaine) and who have high-risk behaviors or an unstable lifestyle. This finding reinforces the role of NEPs as potential focal points for intervention in this hard-to-reach population.

Social determinants predict needle‐sharing behaviour among injection drug users in Vancouver, Canada

Despite the fact that needle exchange was introduced in Vancouver as early as 1988, needle sharing remains common. An analysis was conducted to identify determinants of borrowing used needles among subjects participating in a case-control study. IDUs had a documented HIV seroconversion after 1 January, 1994 (n = 89), or repeatedly tested HIV-seronegative after this date (n = 192). Interviewer-administered questionnaires focused on drug use, sexual behaviours, source of needles and depression. Subjects were asked if they had "ever been forced to have sex" as a child, youth or adult. Logistic regression identified determinants of borrowing needles. After controlling for HIV serostatus, factors independently associated with borrowing were injecting > 4 times/day, polydrug use, and ever experiencing non-consensual sex (AOR = 3.4, 95% CI: 1.8, 6.5). Depression was associated with borrowing, although not independently so. Homosexual activity was independently associated with borrowing among males, whereas living with a sexual partner was an independent predictor for females. Access or barriers to clean needle use were not associated with borrowing. Social determinants, particularly a history of sexual abuse, are among the most significant predictors of needle borrowing among Vancouver's IDUs. Early identification of these factors should be a component of HIV prevention programmes.