Kora DeBeck

Smoking of crack cocaine as a risk factor for HIV infection among people who use injection drugs

Background: Little is known about the possible role that smoking crack cocaine has on the incidence of HIV infection. Given the increasing use of crack cocaine, we sought to examine whether use of this illicit drug has become a risk factor for HIV infection. Methods: We included data from people participating in the Vancouver Injection Drug Users Study who reported injecting illicit drugs at least once in the month before enrolment, lived in the greater Vancouver area, were HIV-negative at enrolment and completed at least 1 follow-up study visit. To determine whether the risk of HIV seroconversion among daily smokers of crack cocaine changed over time, we used Cox proportional hazards regression and divided the study into 3 periods: May 1, 1996–Nov. 30, 1999 (period 1), Dec. 1, 1999–Nov. 30, 2002 (period 2), and Dec. 1, 2002–Dec. 30, 2005 (period 3). Results: Overall, 1048 eligible injection drug users were included in our study. Of these, 137 acquired HIV infection during follow-up. The mean proportion of participants who reported daily smoking of crack cocaine increased from 11.6% in period 1 to 39.7% in period 3. After adjusting for potential confounders, we found that the risk of HIV seroconversion among participants who were daily smokers of crack cocaine increased over time (period 1: hazard ratio [HR] 1.03, 95% confidence interval [CI] 0.57–1.85; period 2: HR 1.68, 95% CI 1.01–2.80; and period 3: HR 2.74, 95% CI 1.06–7.11). Interpretation: Smoking of crack cocaine was found to be an independent risk factor for HIV seroconversion among people who were injection drug users. This finding points to the urgent need for evidence-based public health initiatives targeted at people who smoke crack cocaine.

Police and public health partnerships: Evidence from the evaluation of Vancouver's supervised injection facility

In various settings, drug market policing strategies have been found to have unintended negative effects on health service use among injection drug users (IDU). This has prompted calls for more effective coordination of policing and public health efforts. In Vancouver, Canada, a supervised injection facility (SIF) was established in 2003. We sought to determine if local police impacted utilization of the SIF. We used generalized estimating equations (GEE) to prospectively identify the prevalence and correlates of being referred by local police to Vancouvers SIF among IDU participating in the Scientific Evaluation of Supervised Injecting (SEOSI) cohort during the period of December 2003 to November 2005. Among 1090 SIF clients enrolled in SEOSI, 182 (16.7%) individuals reported having ever been referred to the SIF by local police. At baseline, 22 (2.0%) participants reported that they first learned of the SIF via police. In multivariate analyses, factors positively associated with being referred to the SIF by local police when injecting in public include: sex work (Adjusted Odds Ratio [AOR] = 1.80, 95%CI 1.28 – 2.53); daily cocaine injection (AOR = 1.54, 95%CI 1.14 – 2.08); and unsafe syringe disposal (AOR = 1.46, 95%CI 1.00 – 2.11). These findings indicate that local police are facilitating use of the SIF by IDU at high risk for various adverse health outcomes. We further found that police may be helping to address public order concerns by referring IDU who are more likely to discard used syringes in public spaces. Our study suggests that the SIF provides an opportunity to coordinate policing and public health efforts and thereby resolve some of the existing tensions between public order and health initiatives.

Modelling crack cocaine use trends over 10 years in a Canadian setting

INTRODUCTION AND AIMS Crack cocaine use among illicit drug users is associated with a range of health and community harms. However, long-term epidemiological data documenting patterns and risk factors for crack use initiation remain limited especially among injection drug users. We investigated longitudinal patterns of crack cocaine use among polydrug users in Vancouver, Canada. DESIGN AND METHODS We examined the rate of crack use among injection drug users enrolled in a prospective cohort study in Vancouver, Canada between 1996 and 2005. We also used a Cox proportional hazards regression analysis to identify independent predictors of crack use initiation among this population. RESULTS In total, 1603 injection drug users were recruited between May 1996 and December 2005. At baseline, 7.4% of participants reported ever using crack and this rate increased to 42.6% by the end of the study period (Mantel trend test P < 0.001). Independent predictors of crack use initiation during the study period included frequent cocaine injection, crystal methamphetamine injection, residency in the citys drug using epicenter and involvement in the sex trade (all P < 0.05). DISCUSSION AND CONCLUSIONS These findings demonstrate a massive increase in crack use among injection drug users in a Canadian setting. Our findings also highlight the complex interactions that contribute to the initiation of crack use among injection drug users and suggest that evidence-based interventions are urgently needed to address crack use initiation and to address harms associated with its ongoing use.

Homelessness Independently Predicts Injection Drug Use Initiation Among Street-Involved Youth in a Canadian Setting

PURPOSE 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. METHODS We derived data from the At-Risk Youth Study, a prospective cohort of street-involved youth aged 14-26 years, recruited between September 2005 and November 2011. We used Cox proportional hazards regression to identify factors independently associated with time to injection initiation. RESULTS Among 422 street-youth who had never injected at baseline, we observed 77 injection initiation events during follow-up. Homelessness was independently associated with injection initiation in multivariate Cox regression (relative hazard, 1.80 [95% confidence interval, 1.13-2.87]) after adjusting for crystal methamphetamine use and other potential confounders. CONCLUSIONS 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 within this high-risk population.

Public injecting among a cohort of injecting drug users in Vancouver, Canada

Background: Despite the implementation of policy interventions to address open drug consumption, public injecting continues to occur in many urban settings. This study sought to examine public injecting among a community-recruited cohort of injecting drug users (IDUs) in Vancouver. Methods: The prevalence and correlates of recent public injecting among participants enrolled in the Vancouver Injection Drug User Study during the period of 1 December 2003 to 30 November 2005 were examined prospectively using generalised estimating equations (GEEs). Results: Among the sample of 620 active IDUs, at some point during the study period, 142 (22.9%) individuals reported “usually” or “always” injecting in public in the 6 months prior to their study visit. Factors that were significant and positively associated with recent frequent public injecting in multivariate GEE analysis include homelessness (adjusted OR (AOR) 6.70); frequent crack use (AOR 1.48); and frequent heroin injection (AOR 1.56). Recent frequent public injecting was found to be negatively associated with cooking and filtering drugs prior to injecting (AOR 0.50) and older age (AOR 0.95). Conclusion: The findings indicate that a substantial proportion of local IDUs frequently inject in public, and those who report recently injecting in public spaces appear to be a vulnerable population facing significant health hazards. The provision of secure housing may have the potential to protect the health of IDUs in this setting and significantly decrease the prevalence of public injecting. In addition, the findings support previous work suggesting that removing barriers to the use of Vancouver’s existing supervised injection site may serve to further reduce public drug use.

Incarceration and drug use patterns among a cohort of injection drug users.

AIMS 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). DESIGN 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 McNemars 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. FINDINGS 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). CONCLUSIONS 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.

Interest in low-threshold employment among people who inject illicit drugs: Implications for street disorder

BACKGROUND Income generation opportunities available to people who use illicit drugs have been associated with street disorder. Among a cohort of injection drug users (IDU) we sought to examine street-based income generation practices and willingness to forgo these sources of income if other low-threshold work opportunities were made available. METHODS Data were derived from a prospective community recruited cohort of IDU. We assessed the prevalence of engaging in disorderly street-based income generation activities, including sex work, drug dealing, panhandling, and recycling/salvaging/vending. Using multivariate logistic regressions based on Akaike information criterion and the best subset selection procedure, we identified factors associated with disorderly income generation activities, and assessed willingness to forgo these sources of income during the period of November 2008 to July 2009. RESULTS Among our sample of 874 IDU, 418 (48%) reported engaging in a disorderly income generation activity in the previous six months. In multivariate analyses, engaging in disorderly income generation activities was independently associated with high intensity stimulant use, as well as binge drug use, having encounters with police, being a victim of violence, sharing used syringes, and injecting in public areas. Among those engaged in disorderly income generation, 198 (47%) reported a willingness to forgo these income sources if given opportunities for low-threshold employment, with sex workers being most willing to engage in alternative employment. CONCLUSION Engagement in disorderly street-based income generation activities was associated with high intensity stimulant drug use and various markers of risk. We found that a high proportion of illicit drug users were willing to cease engagement in these activities if they had options for causal low-threshold employment. These findings indicate that there is a high demand for low-threshold employment that may offer important opportunities to reduce drug-related street disorder and associated harms.

Declining Incidence of Hepatitis C Virus Infection among People Who Inject Drugs in a Canadian Setting, 1996-2012

Background People who inject drugs (PWID) are at high risk of hepatitis C virus (HCV) infection. Trends in HCV incidence and associated risk factors among PWID recruited between 1996 and 2012 in Vancouver, Canada were evaluated. Methods Data were derived from a long-term cohort of PWID in Vancouver. Trends in HCV incidence were evaluated. Factors associated with time to HCV infection were assessed using Cox proportional hazards regression. Results Among 2,589, 82% (n = 2,121) were HCV antibody-positive at enrollment. Among 364 HCV antibody-negative participants with recent (last 30 days) injecting at enrollment, 126 HCV seroconversions were observed [Overall HCV incidence density: 8.6 cases/100 person-years (py); 95% confidence interval (95% CI): 7.2, 10.1; HCV incidence density among those with injecting during follow-up: 11.5 cases/100 py; 95% CI 9.7, 13.6]. The overall HCV incidence density declined significantly from 25.0/100 py (95% CI: 20.2, 30.3) in 1996–99, as compared to 6.0/100 py (95% CI: 4.1, 8.5) in 2000–2005, and 3.1/100 py (95% CI: 2.0, 4.8) in 2006–2012. Among those with injecting during follow-up, the overall HCV incidence density declined significantly from 27.9/100 py (95% CI: 22.6, 33.6) in 1996–99, as compared to 7.5/100 py (95% CI: 5.1, 10.6) in 2000–2005, and 4.9/100 py (95% CI: 3.1, 7.4) in 2006–2012. Unstable housing, HIV infection, and injecting of cocaine, heroin and methamphetamine were independently associated with HCV seroconversion. Conclusions HCV incidence has dramatically declined among PWID in this setting. However, improved public health strategies to prevent and treat HCV are urgently required to reduce HCV-associated morbidity and mortality.

Phylogenetic clustering of hepatitis C virus among people who inject drugs in Vancouver, Canada

Little is known about factors associated with hepatitis C virus (HCV) transmission among people who inject drugs (PWID). Phylogenetic clustering and associated factors were evaluated among PWID in Vancouver, Canada. Data were derived from the Vancouver Injection Drug Users Study. Participants who were HCV antibody‐positive at enrolment and those with HCV antibody seroconversion during follow‐up (1996 to 2012) were tested for HCV RNA and sequenced (Core‐E2 region). Phylogenetic trees were inferred using maximum likelihood analysis and clusters were identified using ClusterPicker (90% bootstrap threshold, 0.05 genetic distance threshold). Factors associated with clustering were assessed using logistic regression. Among 655 eligible participants, HCV genotype prevalence was: G1a: 48% (n = 313), G1b: 6% (n = 41), G2a: 3% (n = 20), G2b: 7% (n = 46), G3a: 33% (n = 213), G4a: <1% (n = 4), G6a: 1% (n = 8), G6e: <1% (n = 1), and unclassifiable: 1% (n = 9). The mean age was 36 years, 162 (25%) were female, and 164 (25%) were HIV+. Among 501 participants with HCV G1a and G3a, 31% (n = 156) were in a pair/cluster. Factors independently associated with phylogenetic clustering included: age <40 (versus age ≥40, adjusted odds ratio [AOR] = 1.64; 95% confidence interval [CI] 1.03, 2.63), human immunodeficiency virus (HIV) infection (AOR = 1.82; 95% CI 1.18, 2.81), HCV seroconversion (AOR = 3.05; 95% CI 1.40, 6.66), and recent syringe borrowing (AOR 1.59; 95% CI 1.07, 2.36). Conclusion: In this sample of PWID, one‐third demonstrated phylogenetic clustering. Factors independently associated with phylogenetic clustering included younger age, recent HCV seroconversion, prevalent HIV infection, and recent syringe borrowing. Strategies to enhance the delivery of prevention and/or treatment strategies to those with HIV and recent HCV seroconversion should be explored, given an increased likelihood of HCV transmission in these subpopulations. (Hepatology 2014;60:1571–1580)

The effectiveness of anti-illicit-drug public-service announcements: a systematic review and meta-analysis

Background Anti-illicit-drug public-service announcements (PSAs) have become a cornerstone of drug policy in the USA. However, studies of the effectiveness of these interventions have not been subjected to a systematic evaluation. Methods The authors searched 10 electronic databases along with major conference abstract databases (from inception until 15 February 2010) for all articles and abstracts that evaluated the effectiveness of anti-illicit-drug PSAs. The authors evaluated all studies that assessed intention to use illicit drugs and/or levels of illicit-drug use after exposure to PSAs, and conducted meta-analyses of these studies. Results The authors identified seven randomised trials (n=5428) and four observational trials (n=17 404). Only one randomised trial showed a statistically significant benefit of PSAs on intention to use illicit drugs, and two found evidence that PSAs significantly increased intention to use drugs. A meta-analysis of eligible randomised trials demonstrated no significant effect. Observational studies showed evidence of both harmful and beneficial effects. Conclusion Existing evidence suggests that the dissemination of anti-illicit-drug PSAs may have a limited impact on the intention to use illicit drugs or the patterns of illicit-drug use among target populations.