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5.  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 addition 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.
PMCID: PMC3456224  PMID: 14709714
Anti-HIV agents; HIV infections; Human; Logistic regression models; Substance abuse; Intravenous; Alcohol; Prison
6.  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 neigh-borbood 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.
PMCID: PMC3455981  PMID: 12930883
Harin reduction; HIV/AIDS; Peer; Vancouver; VANDU
7.  Predictors of Early Hospital Readmission in HIV-infected Patients with Pneumonia 
Although hospitalization patterns have been studied, little is known about hospital readmission among HIV-infected patients in the era of highly active antiretroviral therapy. We explored the risk factors for early readmission to a tertiary care inner-city hospital among HIV-infected patients with pneumonia in Vancouver, Canada.
Case-control study.
Tertiary care, university-affiliated, inner-city hospital.
All HIV-infected patients who were hospitalized with Pneumocystis carinii pneumonia (PCP) or bacterial pneumonia (BP) between January 1997 and December 2000. Case patients included those who had early readmissions, defined as being readmitted within 2 weeks of discharge (N = 131). Control patients were randomly selected HIV-infected patients admitted during the study period who were not readmitted within 2 weeks of discharge (N = 131), matched to the cases by proportion of PCP to BP.
Sociodemographic, HIV risk category, and clinical data were compared using χ2 test for categorical variables, and the Wilcoxon rank-sum test was used for continuous variables. Multivariable logistic regression was performed to determine the factors independently associated with early readmission. We also reviewed the medical records of 132 patients admitted to the HIV/AIDS ward during the study period and collected more detailed clinical data for a subanalysis.
Patients were at significantly increased odds of early readmission if they left the hospital against medical advice (AMA) (adjusted odds ratio [OR], 4.26; 95% confidence interval [95% CI], 2.13 to 8.55), lived in the poorest urban neighborhood (OR, 2.03; 95% CI, 1.09 to 3.77), were hospitalized in summer season (May though October, OR, 2.36; 95% CI, 1.36 to 4.10), or had been admitted in the preceding 6 months (OR, 2.55; 95% CI, 1.46 to 4.47). Gender, age, history of AIDS-defining illness, and injection drug use status were not significantly associated with early readmission.
Predictors of early readmission of HIV-infected patients with pneumonia included: leaving hospital AMA, living in the poorest urban neighborhood, being hospitalized in the preceding 6 months and during the summer months. Interventions involving social work may address some of the underlying reasons why these patients leave hospital AMA and should be further studied.
PMCID: PMC1494845  PMID: 12709090
case-control; hospital readmission; HIV; AIDS; bacterial pneumonia; PCP; antiretroviral therapy
8.  Adherence and plasma HIV RNA responses to highly active antiretroviral therapy among HIV-1 infected injection drug users 
The benefits of highly active antiretroviral therapy (HAART) for the treatment of HIV infection are well documented, but concerns regarding access and adherence to HAART are growing. We evaluated virological responses to HAART among HIV-1 infected patients who were injection drug users (IDUs) in a population-based setting where HIV/AIDS care is delivered free of charge.
We evaluated previously untreated HIV-1 infected men and women who initiated HAART between Aug. 1, 1996, and July 31, 2000, and who were followed until Mar. 31, 2002, in a province-wide HIV treatment program. We used Kaplan–Meier methods and Cox proportional hazards regression in our evaluation of time to suppression (i.e., less than 500 copies/mL) and rebound (i.e., 500 copies/mL or more) of plasma HIV-1 RNA, with patients stratified according to whether or not they had a history of injection drug use.
Overall, 1422 patients initiated HAART during the study period, of whom 359 (25.2%) were IDUs. In Kaplan–Meier analyses, the cumulative suppression rate at 12 months after initiation of HAART was 70.8% for non-IDUs and 51.4% for IDUs (p < 0.001) (these values include people who achieved suppression before 12 months but who might not have been followed for the full 12-month period). Among patients who achieved suppression of plasma HIV-1 RNA, the cumulative rebound rate at 12 months after initial suppression was 23.8% for non-IDUs and 34.7% for IDUs (p < 0.001). However, after adjustment for adherence and other covariates, the rates of HIV-1 RNA suppression (adjusted relative hazard 0.9, 95% confidence interval [CI] 0.7–1.0) and HIV-1 RNA rebound (adjusted relative hazard 1.3, 95% CI 1.0–1.6) were similar between non-IDUs and IDUs. Differences between non-IDUs and IDUs were even less pronounced in subanalyses that considered only therapy-adherent patients (p > 0.1).
Non-IDUs and IDUs had similar rates of HIV-1 RNA suppression and rebound after the initiation of HAART, once lower levels of adherence were taken into account. Nevertheless, the lower virological response rates among IDUs suggest that, unless interventions are undertaken to improve adherence, these patients may experience elevated rates of disease progression and use of medical services in our setting.
PMCID: PMC202281  PMID: 14517122
9.  Impact of supply-side policies for control of illicit drugs in the face of the AIDS and overdose epidemics: investigation of a massive heroin seizure 
More than 93% of the nearly $500 million spent annually on Canada's drug strategy goes toward efforts to reduce the illicit drug supply. However, little is known about the effectiveness of this strategy. On Sept. 2, 2000, Canadian police seized approximately 100 kg of heroin in one of the nation's largest-ever seizures of this drug. An ongoing prospective cohort study of injection drug users afforded an opportunity to evaluate the impact of this seizure.
The Vancouver Injection Drug User Study is a prospective cohort study of injection drug users that began in 1996. The present study relied primarily on data acquired from participants who were seen during the 30-day periods immediately before and after the seizure. We compared drug use and behavioural characteristics, heroin and cocaine prices, and participants' reports of whether law enforcement had affected their source of drugs or the types of drugs available on the street, as well as overdoses, in these 2 periods.
The 138 participants seen before the seizure were similar to the 123 participants seen after the seizure with respect to age, sex, ethnic background, education, HIV serostatus, neighbourhood residence, instability of housing, employment status, use of methadone maintenance therapy and all other measured potential confounders (all p > 0.10). We found no difference in the extent to which participants in the 2 groups reported daily use of heroin, frequency of nonfatal overdoses, or whether law enforcement had affected their source of drugs or the types of drugs available on the street (all p > 0.10). Although we detected no difference in the price of cocaine, the median reported price of heroin went down after the seizure (p = 0.034), which suggests that other shipments compensated for the seizure. External evaluations of deaths from overdoses and heroin purity indicated that the seizure had no impact, nor was any impact seen when the periods of analysis were extended.
The massive heroin seizure appeared to have no measurable public health benefit. Closer scrutiny of enforcement efforts is warranted to ensure that resources are delivered to the most efficient and cost-effective public health programs.
PMCID: PMC140425  PMID: 12538544
10.  Risk factors for elevated HIV incidence among Aboriginal injection drug users in Vancouver 
Because of established links between entrenched poverty and risk of HIV infection, there have long been warnings that HIV/AIDS will disproportionately affect Aboriginal people in Canada. We compared HIV incidence rates among Aboriginal and non-Aboriginal injection drug users (IDUs) in Vancouver and studied factors associated with HIV seroconversion among Aboriginal participants.
This analysis was based on 941 participants (230 Aboriginal people) recruited between May 1996 and December 2000 who were seronegative at enrolment and had completed at least one follow-up visit. Incidence rates were calculated using the Kaplan–Meier method. The Cox proportional hazards regression model was used to identify independent predictors of time to HIV seroconversion among female and male Aboriginal IDUs.
As of May 31, 2001, seroconversion had occurred in 112 (11.9%) of the participants, yielding a cumulative incidence of HIV infection at 42 months of 12.7% (95% confidence interval [CI] 10.3%–15.1%). The cumulative incidence at 42 months was significantly higher among the Aboriginal participants than among the non-Aboriginal participants (21.1% v. 10.7%, p < 0.001). This elevation in risk was present in both female and male Aboriginal IDUs. Among the female Aboriginal IDUs, frequent speedball (combined cocaine and heroin) injection (adjusted relative risk [RR] 3.1; 95% CI 1.4–7.1) and going on binges of injection drug use (adjusted RR 2.3; 95% CI 1.0–5.2) were found to be independent predictors of HIV seroconversion. Among the male Aboriginal IDUs, the independent predictors of seroconversion were frequent speedball injection (adjusted RR 2.9; 95% CI 1.0–8.5) and frequent cocaine injection (adjusted RR 2.5; 95% CI 1.0–6.5).
In Vancouver, Aboriginal IDUs are becoming HIV positive at twice the rate of non-Aboriginal IDUs. Our findings emphasize the urgent need for an appropriate and effective public health strategy — planned and implemented in partnership with Aboriginal AIDS service organizations and the Aboriginal community — to reduce the harms of injection drug use in this population.
PMCID: PMC139313  PMID: 12515780
11.  Leaving hospital against medical advice among HIV-positive patients 
Hospital discharge against medical advice, especially among substance-abusing populations, is a frustrating problem for health care pro-viders. Because of the high prevalence of injection drug use among HIV- positive patients admitted to hospital in Vancouver, we explored the factors associated with leaving hospital against medical advice in this population.
We reviewed records for all HIV/AIDS patients admitted to St. Paul's Hospital, Vancouver, between Apr. 1, 1997, and Mar. 1, 1999. After identifying the first (“index”) admission during this period, we followed the patients' records for 1 year. Multivariate models were applied to identify the determinants of discharge against medical advice and to estimate the impact of such discharge on readmission rate, readmission frequency and length of stay in hospital.
Of 981 index admissions among HIV/AIDS patients, 125 (13%) of the patients left the hospital against medical advice. Departure on the day on which welfare cheques were issued and a history of injection drug use were significant predictors of leaving against medical advice. After adjusting for sex, age, severity of illness, injection drug use and homelessness, we found that patients leaving against medical advice were readmitted more frequently than those who were formally discharged (frequency ratio 1.25, 95% confidence interval [CI] 1.11–1.42), were more likely to be readmitted with a related diagnosis within 30 days (odds ratio 5.00, 95% CI 3.04–8.24) and had significantly longer lengths of stay in the follow-up period.
Discharge against medical advice among HIV-positive patients was associated with frequent readmissions with the same diagnosis. Preventing such discharges is likely to benefit patients (by improving their health status) and the health care system (by reducing unnecessary readmissions).
PMCID: PMC122025  PMID: 12358196
12.  Risk factors for elevated HIV incidence rates among female injection drug users in Vancouver 
In 1997, we found a higher prevalence of HIV among female than among male injection drug users in Vancouver. Factors associated with HIV incidence among women in this setting were unknown. In the present study, we sought to compare HIV incidence rates among male and female injection drug users in Vancouver and to compare factors associated with HIV seroconversion.
This analysis was based on 939 participants recruited between May 1996 and December 2000 who were seronegative at enrolment with at least one follow-up visit completed, and who were studied prospectively until March 2001. Incidence rates were calculated using the Kaplan–Meier method. The Cox proportional hazards regression model was used to identify independent predictors of time to HIV seroconversion.
As of March 2001, seroconversion had occurred in 110 of 939 participants (64 men, 46 women), yielding a cumulative incidence rate of HIV at 48 months of 13.4% (95% confidence interval [CI] 11.0%–15.8%). Incidence was higher among women than among men (16.6% v. 11.7%, p = 0.074). Multivariate analysis of the female participants' practices revealed injecting cocaine once or more per day compared with injecting less than once per day (adjusted relative risk [RR] 2.6, 95% CI 1.4–4.8), requiring help injecting compared with not requiring such assistance (adjusted RR 2.1, 95% CI 1.1–3.8), having unsafe sex with a regular partner compared with not having unsafe sex with a regular partner (adjusted RR 2.9, 95% CI 0.9–9.5) and having an HIV-positive sex partner compared with not having an HIV-positive sex partner (adjusted RR 2.7, 95% CI 1.0–7.7) to be independent predictors of time to HIV seroconversion. Among male participants, injecting cocaine once or more per day compared with injecting less than once per day (adjusted RR 3.3, 95% CI 1.9–5.6), self-reporting identification as an Aboriginal compared with not self-reporting identification as an Aboriginal (adjusted RR 2.5, 95% CI 1.4–4.2) and borrowing needles compared with not borrowing needles (adjusted RR 2.0, 95% CI 1.1–3.4) were independent predictors of HIV infection.
HIV incidence rates among female injection drug users in Vancouver are about 40% higher than those of male injection drug users. Different risk factors for seroconversion for women as opposed to men suggest that sex-specific prevention initiatives are urgently required.
PMCID: PMC100922  PMID: 11949985
13.  Incidence of hepatitis C virus infection among injection drug users during an outbreak of HIV infection 
Beginning in 1994, Vancouver experienced an explosive outbreak of HIV infection among injection drug users (IDUs). The objectives of this study were to measure the prevalence and incidence of hepatitis C virus (HCV) infection in this context and to examine factors associated with HCV seroconversion among IDUs.
IDUs recruited through a study site and street outreach completed interviewer-administered questionnaires covering subjects' characteristics, behaviour, health status and service utilization and underwent serologic testing for HIV and HCV at baseline and semiannually thereafter. A Cox proportional hazards model was used to identify independent correlates of HCV seroconversion.
As of Nov. 30, 1999, 1345 subjects had been recruited into the study cohort. The prevalence of anti-HCV antibodies was 81.6% (95% confidence interval [CI] 79.6% to 83.6%) at enrolment. Sixty-two HCV seroconversions occurred among 155 IDUs who were initially HCV negative and who returned for follow-up, for an overall incidence density rate of 29.1 per 100 person-years (95% CI 22.3 to 37.3). The HCV incidence remained above 16 per 100 person-years over 3 years of observation (December 1996 to November 1999), whereas HIV incidence declined from more than 19 to less than 5 per 100 person-years. Independent correlates of HCV seroconversion included female sex, cocaine use, injecting at least daily and frequent attendance at a needle exchange program.
Because of high transmissibility of HCV among those injecting frequently and using cocaine, the harm reduction initiatives deployed in Vancouver during the study period proved insufficient to eliminate hepatitis C transmission in this population.
PMCID: PMC81496  PMID: 11599327
14.  Hospital utilization and costs in a cohort of injection drug users 
Many injection drug users (IDUs) seek care at emergency departments and some require hospital admission because of late presentation in the course of their illness. We determined the predictors of frequent emergency department visits and hospital admissions among community-based IDUs and estimated the incremental hospital utilization costs incurred by IDUs with early HIV infection relative to costs incurred by HIV-negative IDUs.
The Vancouver Injection Drug User Study (VIDUS) is a prospective cohort study involving IDUs that began in 1996. Our analyses were restricted to the 598 participants who gave informed consent for our study. We used the participants' responses to the baseline VIDUS questionnaire and, from medical records at St. Paul's Hospital, Vancouver, we collected detailed information about the frequency of emergency department visits, hospital admissions and the primary diagnosis for all visits or hospital stays between May 1, 1996, and Aug. 31, 1999. The incremental difference in hospital utilization costs by HIV status was estimated, based on 105 admissions in a subgroup of 64 participants.
A total of 440 (73.6%) of the 598 IDUs made 2763 visits to the emergency department at St. Paul's Hospital during the study period. Of these 440, 265 (60.2%) made frequent visits (3 or more). The following factors were associated with frequent use: HIV-positive status (seroprevalent: adjusted odds ratio [OR] 1.7, 95% confidence interval [CI] 1.2–2.6; seroconverted during study period: adjusted OR 3.0, 95% CI 1.6–5.7); more than 4 injections daily (adjusted OR 1.5, 95% CI 1.1–2.1); cocaine use more frequent than use of other drugs (adjusted OR 2.0, 95% CI 1.2–3.6); and unstable housing (adjusted OR 1.5, 95% CI 1.1–2.2). During the study period 210 of the participants were admitted to hospital 495 times; 118 (56.2%) of them were admitted frequently (2 or more admissions). The 2 most common reasons for admission were pneumonia (132 admissions among 79 patients) and soft-tissue infections (cellulitis and skin abscess) (90 admissions among 59 patients). The following factors were independently associated with frequent hospital admissions: HIV-positive status (seroprevalent: adjusted OR 5.4, 95% CI 3.4–8.6; seroconverted during study period: adjusted OR 2.9, 95% CI 1.4–6.0); and female sex (adjusted OR 1.8, 95% CI 1.1–3.1). The incremental hospital utilization costs incurred by HIV-positive IDUs relative to the costs incurred by HIV-negative IDUs were $1752 per year.
Hospital utilization was significantly higher among community-based IDUs with early HIV disease than among those who were HIV negative. Much of the hospital use was related to complications of injection drug use and may be reduced with the establishment of programs that integrate harm reduction strategies with primary care and addiction treatment.
PMCID: PMC81365  PMID: 11531049
15.  Unsafe injection practices in a cohort of injection drug users in Vancouver: Could safer injecting rooms help? 
In several European countries safer injecting rooms have reduced the public disorder and health-related problems of injection drug use. We explored factors associated with needle-sharing practices that could potentially be alleviated by the availability of safer injecting rooms in Canada.
The Vancouver Injection Drug User Study is a prospective cohort study of injection drug users (IDUs) that began in 1996. The analyses reported here were restricted to the 776 participants who reported actively injecting drugs in the 6 months before the most recent follow-up visit, during the period January 1999 to October 2000. Needle sharing was defined as either borrowing or lending a used needle in the 6-month period before the interview.
Overall, 214 (27.6%) of the participants reported sharing needles during the 6 months before follow-up; 106 (13.7%) injected drugs in public, and 581 (74.9%) reported injecting alone at least once. Variables independently associated with needle sharing in a multivariate analysis included difficulty getting sterile needles (adjusted odds ratio [OR] 2.7, 95% confidence interval [CI] 1.8–4.1), requiring help to inject drugs (adjusted OR 2.0, 95% CI 1.4–2.8), needle reuse (adjusted OR 1.8, 95% CI 1.3–2.6), frequent cocaine injection (adjusted OR 1.6, 95% CI 1.1–2.3) and frequent heroin injection (adjusted OR 1.5, 95% CI 1.04–2.1). Conversely, HIV-positive participants were less likely to share needles (adjusted OR 0.5, 95% CI 0.4–0.8), although 20.2% of the HIV-positive IDUs still reported sharing needles.
Despite the availability of a large needle-exchange program and targeted law enforcement efforts in Vancouver, needle sharing remains an alarmingly common practice in our cohort. We identified a number of risk behaviours — difficulty getting sterile needles, needle sharing and reuse, injection of drugs in public and injecting alone (one of the main contributing causes of overdose) — that may be alleviated by the establishment of supervised safer injecting rooms.
PMCID: PMC81364  PMID: 11531048
16.  The social determinants of emergency department and hospital use by injection drug users in Canada 
The aim of this study was to describe the relationship between sociodemographic characteristics and human immunodeficiency (HIV) status of a cohort of injection drug users (IDUs) on their self-reported health service utilization.
Interviewer-administered questionnaire.
IDUs who had injected illicit drugs within the previous month were recruited through street outreach. They underwent serology for HIV-1 and questionnaires on demographics, drug using behaviors, housing status, and health service utilization (hospitalization overnight and emergency department visits) in the previous 6 months. Logistic regression analysis was used to identify independent associations with the use of health services.
Of 1,103 cohort participants, 65% were male, 63% were white, and 23% were HIV positive. Cocaine was the most frequently injected drug used. Almost half (47%) had used health services in the previous 6 months. The following variables were associated independently with health service utilization (adjusted odds ratio; 95% confidence interval): unstable housing, defined as living primarily in a hotel, boarding room, or transition house or on the street in the past 6 months (1.44; 1.11–1.86); female gender (1.45; 1.11–1.89); HIV-positive status (1.43; 1.06–1.92); injection of cocaine (1.50; 1.12–2.02); and primary care physician visit in past 6 months (1.91; 1.39–2.64).
IDUs with unstable housing were more likely to report emergency department and hospital use, which may be a reflection of their disorganized lifestyle or poorer health status. Further studies are required to assess the effect on the health status and health care use of IDUs of interventions that increase the availability of safe, affordable housing.
PMCID: PMC3456690  PMID: 10609591
Canada; Drug Users; Health Services Utilization; Hospitalization; Housing

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