In North America, high HIV incidence rates have been observed in many urban areas as a result of illicit injection drug use (IDU), 1,2 and illicit drug overdoses are a leading cause of death. 3–5 In Canada, an Auditor General's report recently estimated that of the $454 million spent annually on Canada's drug strategy in 2000, $426 million (93.8%) was devoted to enforcement-based initiatives with the remaining 6.2% being shared between prevention and treatment. 6 A similar apportionment of resources to criminal justice interventions is seen in a variety of countries including the United States. 7,8
As a result, in most North American settings, the demand for addiction treatment services substantially exceeds availability, 7,9–11 and in our setting, the emergence of the HIV epidemic has been attributed, in part, to reductions in funding for addiction services in the mid-1990s. 12 In Canada, the universal health care system is such that all medical care is provided free of charge; however, as noted, funding for addiction treatments has been scaled back in recent years. 12 The responsibility for providing addiction treatment is primarily with the provincial government, although the long waiting lists for the government-funded treatment programs that exist have resulted in an increasing number of private facilities that are too expensive for street-based IDUs.
In the present study, we hypothesized that IDUs at highest risk of HIV infection would be most likely to seek addiction treatment. In light of this, and since demand for addiction treatment exceeds availability in our setting, 12 the present study was conducted to examine whether inability to access addiction treatment was associated with HIV risk behavior among a cohort of HIV-negative IDUs.
Beginning in May 1996, persons who had injected illicit drugs in the previous month were recruited into the Vancouver Injection Drug User Study (VIDUS), a prospective cohort study that has been described in detail previously. 13–15 Briefly, as of May 2002, 1478 study subjects had been recruited through self-referral and street outreach, and data collection for the project was conducted in a storefront office. Persons were eligible if they had injected illicit drugs at least once in the previous month, resided in the greater Vancouver region, and provided written informed consent.
The primary endpoint in the present analysis was receptive syringe sharing (“borrowing”). In the VIDUS questionnaire, participants are asked to report any syringe borrowing that has occurred in the 6-month period prior to the interview. For reasons outlined here, we hypothesized that IDUs at greatest risk of HIV infection would also be more likely to report that they had sought, but been unable to access, addiction treatment during this period. Since syringe borrowing does not pose a risk of acquiring HIV infection for HIV-positive IDUs, to avoid confounding based on serostatus, we performed an analysis that evaluated factors associated with syringe borrowing that was restricted to HIV-negative IDUs. As such, all baseline HIV-negative individuals were eligible until the end of follow-up if they remained persistently HIV negative, or until the first visit at which an incident HIV infection was confirmed for IDUs who became HIV infected during follow-up.
Variables of Interest
Variables of interest in this analysis included baseline sociodemographics: age, gender, ethnicity (Aboriginal vs. other), education level (completed high school vs. less than high school), and years injecting, as well as time-updated variables relating to behaviors in the previous 6 months including residence in Vancouver's Downtown Eastside (herein referred to as the HIV epicenter), unstable housing, reporting an unsuccessful attempt to access addiction treatment, daily heroin and cocaine injection, “crack” cocaine smoking, methadone maintenance therapy, sex trade involvement, requiring help injecting, and binge use of drugs. 13,16 We were liberal in our definition of drug treatment, which could include detoxification programs, recovery houses, alcohol or illicit drug treatment centers, spiritual healers, addiction counselors, methadone maintenance therapy, and peer-based recovery programs such as Alcoholics Anonymous and Narcotics Anonymous. Inability to access addiction treatment was based on the question: “In the last 6 months, have you ever tried to access any alcohol or other drug treatment, but were unable to?”
Since analyses of factors associated with syringe borrowing included serial measures for each subject, we used generalized estimating equations (GEEs) for binary outcomes with logit link for the analysis of correlated data to determine which factors were independently associated with syringe borrowing. 17 These methods provided standard errors adjusted by multiple observations per person using an exchangeable correlation structure.
The multivariate model was fit using the a priori defined model building protocol of adjusting for all variables that were statistically significant at the P < 0.05 level in bivariate analyses. In addition, we were aware that persons who did not seek addiction treatment could do so as a result of unwillingness to initiate treatment, being already enrolled in addiction treatment, or cessation or reduction of IDU. Alternatively, we also recognized that those already in one form of addiction treatment, such as a detoxification program, may seek but be unable to access more comprehensive care, such as a residential treatment facility or methadone maintenance therapy. We therefore decided a priori to adjust the final multivariate model for the level of heroin and cocaine use, enrollment in methadone maintenance therapy, and enrollment in other forms of addiction treatment regardless of whether they were statistically associated with syringe borrowing in univariate analyses. All statistical analyses were performed using SAS software version 8.0 (SAS, Cary, NC). All P values are 2-sided.
Between May 1996 and May 2002, 1478 individuals had been enrolled into the VIDUS cohort through ongoing recruitment. Among the 1478 individuals recruited during the study period, 318 individuals were found to be HIV infected at baseline and 3 individuals were excluded from further analyses due to missing data. Among the 1157 eligible study subjects, only 228 (19.7%) of IDUs were in addiction treatment at baseline. Of the 929 individuals who were not in addiction treatment at baseline, 255 (27.5%) reported enrolling in addiction treatment during follow-up and 314 (33.8%) reported having sought but been unable to access addiction treatment during follow-up. Overall, 117 individuals who were HIV negative at baseline became HIV infected during follow-up, and follow-up measures subsequent to the first HIV-positive test were excluded from subsequent analyses. Among these 117 individuals, 35 (29.9%) reported borrowing a used syringe in the 6 months prior to seroconversion, and 10 (8.6%) reported that they had sought but been unable to access addiction treatment in the 6 months prior to seroconversion. Among the 1157 individuals who were HIV negative at baseline, the median number of semiannual follow-up visits was 5 (interquartile range 2–8).
The crude proportion of baseline HIV-negative individuals reporting syringe borrowing in the 6 months prior to the baseline visit and during the first 5 follow-up visits, stratified by whether the IDU reported having had an unsuccessful attempt to access addiction treatment in the prior 6 months, is shown in Figure 1. As shown here, crude inspection of the data suggested elevated rates of syringe borrowing in the 6 months prior to the interview among IDUs who also reported having had an unsuccessful attempt to access addiction treatment during this period.
In bivariate GEE logistic analyses, syringe borrowing was associated with male sex (odds ratio [OR] = 1.30), younger age (OR = 0.98 per year older), Aboriginal ethnicity (OR = 0.74), years injecting (OR = 0.99 per year longer), unstable housing (OR = 1.34), frequent heroin (OR = 1.97) and cocaine (OR = 1.91) injection, methadone use (OR = 0.84), sex trade involvement (OR = 1.96), requiring help injecting (OR = 3.18), binge drug use (OR = 2.18), and difficulty accessing syringes (OR = 3.70). Similarly, reporting having sought but been denied addiction treatment was associated with syringe borrowing in univariate analyses (OR = 1.72).
Table 1 shows the results of the multivariate GEE analysis that included all variables that were significant in bivariate analyses. As shown here, having had an unsuccessful attempt to access addiction treatment was independently associated with syringe borrowing during follow-up (adjusted OR = 1.29 [95% CI 1.09–1.53]; P = 0.003). The adjusted ORs and 95% CIs for the other variables independently associated with syringe borrowing including daily cocaine and heroin injection, difficulty accessing syringes, requiring help injecting, and binge drug use are shown in Table 1. Note these estimates are also adjusted for the sociodemographic characteristics noted in the footnote of the table.
In the present study, we found that only 20% of IDUs were enrolled in addiction treatment at baseline. This finding must be underscored as a major concern to Canadian health policy makers, given the substantial health, community, and fiscal costs of untreated addiction and the potential cost savings and reduction in human suffering that could accrue from the provision of these services. 10,18–20 Furthermore, in prospective analyses, we found that unsuccessful attempts to access addiction treatment services were independently associated with syringe borrowing among IDUs at risk for HIV infection.
The most obvious explanation for our findings is that the most unstable and highest-risk IDUs were the most likely to seek addiction treatment but were unable to access these services due to lack of availability. This explanation is supported by previous studies that have suggested that high-risk illicit drug users, 21–23 and illicit drug users who perceive themselves to be high risk, 24 may be the most likely to initiate addiction treatment. It is noteworthy, however, that inability to access addiction treatment services remained strongly associated with syringe borrowing after substantial covariate adjustment for several markers of drug use intensity, including daily cocaine and heroin injection. 5,13 Furthermore, we also adjusted our analyses for environmental and other risk factors that have been associated with high-risk syringe sharing in our setting, including difficulty accessing syringes 16 and requiring help injecting, 25 and yet the association persisted. Although residual confounding can never be ruled out in observational analyses, further study is required to evaluate this association since it is also plausible that failed attempts to access addiction treatment may promote depression, anxiety, or other psychologic risk factors for syringe sharing. 26,27
Nevertheless, from a public health perspective, whether IDUs sought addiction treatment before or after syringe sharing is of only limited relevance. Obviously, under ideal circumstances, all IDUs who were at risk for future syringe sharing would initiate addiction treatment services and could be prevented from engaging in injection-related risk behavior. 28 Alternatively, however, potential for substantial public health benefit could also accrue from treatment initiation among IDUs who had recently shared a syringe. For example, addiction treatment initiation among these individuals could help to identify newly acquired HIV infections and potentially reduce the risk of transmission to others. 29 Furthermore, it is also likely that IDUs who engage in syringe sharing may do so multiple times 13 and that initiation of addiction treatment could prevent future syringe borrowing among IDUs who placed themselves at risk but did not become infected after the first syringe-sharing event.
Unfortunately, in many settings in North America, including our own, these potential public health benefits of treatment-seeking behavior are not realized. This is because the demand for addiction treatment often substantially exceeds availability. 7,9–12,30,31 These findings have a high degree of relevance for health policy makers since provision of addiction treatment has the potential to be highly cost effective given the substantial community costs of untreated illicit drug use and the significant health care costs of treating blood-borne infections including HIV and hepatitis C. 9,10,32,33
While some studies have suggested that self-reports of IDUs are valid, 34 syringe sharing is a stigmatized behavior and it is possible that syringe borrowing rates were underestimated in the present study. 35 Conversely, we should note that addiction treatment–seeking behavior may also be subject to this concern, and if so we may have overestimated the rate of addiction treatment–seeking behavior. In addition, as noted, a limitation of the present study was that we were unable to discern whether syringe sharing occurred before or after treatment-seeking behavior, although for reasons outlined previously, this may be more of an academic question than a limitation that diminishes the public health relevance of our findings. Finally, a limitation of the present study was that we were unable to determine the HIV serostatus of those from whom syringes were lent or the extent to which used syringes were cleaned prior to use.
In summary, we found that <20% of IDUs were enrolled in addiction treatment at baseline. In prospective analyses, we found that unsuccessful attempts to access addiction treatment services were independently associated with syringe borrowing among IDUs at risk for HIV infection. This finding has a high degree of relevance to public health policy makers and suggests that the limited provision of addiction treatment may result in a major missed opportunity to reduce HIV transmission behavior among IDUs. These findings also support the substantial scientific literature indicating that major medical cost savings and the substantial reduction in community harm may accrue from the expansion of addiction treatment services. 7,9,10,28
The authors thank all of the participants of the VIDUS project. We also thank Bonnie Devlin, John Charette, Kathy, Churchill, Caitlin Johnston, Robin Brooks, Steve Kain, Guillermo Fernandez, Peter Vann, and Nancy Laliberte for their research and administrative assistance.
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