EVALUATING VANCOUVER'S SUPERVISED INJECTION FACILITY:

DATA AND DOLLARS, SYMBOLS AND ETHICS

Insite, Vancouver's supervised injection facility for injection drug
users, opened in 2003 under an exemption from Canadian federal drug
laws. A substantial amount of research has since been conducted on the
facility (www.vch.ca/sis/). Although randomized controlled trials have
not been possible, the research has indicated substantial public
health benefits associated with the facility's operation.

In this issue, Bayoumi and Zaric present a model of the
cost-effectiveness of Insite.1 The model's basic comparison is between
other interventions for the prevention of HIV infection in Vancouver,
such as needle-exchange programs and methadone maintenance treatment,
and these interventions plus Insite. Although the authors recognize
great potential variation of the cost-effectiveness in their
sensitivity analyses, some of their model's assumptions are
questionable. Most importantly, the model generates an incidence rate
of HIV infection of 5-6 per 100 person-years over their 10-year time
horizon. This estimated rate forces us to challenge their
cost-effectiveness model.

The defining characteristics of successful HIV prevention among
injection drug users are the reduction of the HIV incidence rate to a
low level, typically less than 2 per 100 person-years at risk, and the
maintainance of the reduced rate over long periods.2-4 In the
Vancouver Injection Drug Users Study, the incidence rate of HIV
infection among injection drug users in Vancouver was 1-2 per 100
person-years in 2000, before the existence of Insite.5 Allowing for a
cohort effect in the study, the rate should have remained at 2-3 per
100 person-years since then.

A comparison with New York City may be helpful here. A large-scale
expansion of needle-exchange programs in that city was followed by a
reduction in the HIV incidence rate among injection drug users from 4
to 1 per 100 person-years.6 If the incidence rate were to return to 4
per 100 person-years, we would conclude that the system for preventing
HIV infection among injection drug users in New York City was clearly
failing. Similarly, if the rate among injection drug users in
Vancouver were now to rise to and remain at 5-6 per 100 person-years,
we would have to conclude that something had gone wrong with
Vancouver's system to prevent HIV infection.

Successful HIV prevention among injection drug users relies not only
on a reduction of the number of unsafe injections, but also on other
mechanisms such as partner restriction (in which sharing is confined
within small, stable groups) and informed altruism (in which users who
know they are seropositive volunteer to inject last when a syringe is
shared).7 Such mechanisms can greatly reduce HIV transmission without
necessarily reducing shared injections. Modelling based on needle
sharing that does not include these types of mechanisms is likely to
overestimate HIV transmission among injection drug users.

It is inappropriate to assess Insite within a model that assumes HIV
prevention among injection drug users is not succeeding in Vancouver
as a whole. However, we do not wish to overemphasize our differences,
because we still believe that the facility is likely cost-effective.
The relation between needle sharing and incident HIV infections is
inherently difficult to model. However, the 21% of injection drug
users assumed by Bayoumi and Zaric to be using Insite regularly and to
have a decreased frequency of needle sharing clearly have multiple
risk factors for HIV infection. We estimate that, in the absence of
Insite services, the incidence of HIV infection in this group would be
about 4-5 per 100 person-years (about double the rate among injection
drug users as a whole). If Insite's services simply reduce this rate
to the average of 2-3 per 100 person-years among injection drug users
in Vancouver, about 20-30 new HIV infections would be averted per
year. With allowances for growth in the population of injection drug
users over time, this would equal about 250-350 averted infections
over 10 years, albeit substantially fewer than the 1191 estimated by
Bayoumi and Zaric. Given the estimated lifetime medical cost of $150
000 to treat HIV,8 Insite will be cost saving if it prevents a modest
number of HIV infections per year. More importantly, we believe that
the threat by the Canadian government in 2007 not to extend Insite's
exemption from federal drug laws was not based on assessments of the
facility's cost-effectiveness. Instead, it appeared to be based on the
symbolic value of Insite as a service that either encourages illicit
drug use or provides needed health services to injection drug users.

Recent research has indicated that stigmatization of extreme
out-groups such as drug addicts is not simply a matter of a lack of
information about the groups but that it involves different mental
processes. In their study, Harris and Fiske9 found that, although
functional magnetic resonance imaging showed activation of the medial
frontal cortex while participants were thinking about social groups in
general, no such activation was observed when they were thinking about
extreme out-groups such as drug addicts. The authors concluded that
the participants were showing a reaction of disgust toward drug
addicts and were perceiving them to be "less than human."

Decision-making about controversial public health projects such as
Insite may thus be primarily a function of emotional reactions to drug
addicts of disgust, dehumanization and stigmatization rather than
reactions of sympathy, humanity and the right to optimal health for
all, which one would hope would be the framework for assessing the
effectiveness of public health interventions. Within a
disgust/dehumanization framework, effectiveness and cost-effectiveness
are usually not important aspects of a program or policy. Rather, it
is the congruency between the symbolic value of the program and the
emotions of disgust, dehumanization and stigmatization that is critical.

Within a framework designed to protect the health of drug users and of
the communities in which they live, it is critical to use the best
available evidence to allocate scarce resources.10 As noted earlier,
almost any intervention that reduces the incidence of HIV infection in
a developed country such as Canada is likely to be cost-effective.
However, HIV prevention programs for injection drug users should meet
3 other criteria. First, the intervention should be targeted to those
at relatively high risk for transmitting HIV. Second, the intervention
should be linked to other health and social services. Vulnerable
populations such as injection drug users typically have multiple
needs; therefore, individual programs should provide multiple services
on site and through referrals. Third, the intervention should be
supported by drug users and the local community. Such support is
needed for the intervention to be used and sustained. Based on the
evidence to date, Vancouver's supervised injection facility not only
saves costs, it also meets these broader criteria for
effectiveness.

See related research paper by Bayoumi and Zaric, page 1143
http://www.cmaj.ca/cgi/content/full/cmaj;179/11/1143

KEY POINTS

- - Insite, Vancouver's supervised injection facility, is currently
under threat of being closed.

- - Estimates of future incidence rates of HIV infection among injection
drug users in Vancouver vary greatly, from 2-3 per 100 person-years to
5-6 per 100 person-years.

- - This variation depends on the assumptions made about the overall
effectiveness of efforts to prevent HIV infection in this population.

- - The number of HIV infections averted per year because of Insite's
services also varies with the different assumptions.

- - Despite these variations, Insite is likely to be
cost-effective.

- - The threat to close Insite appears to be based more on emotional
reactions to the facility and drug addicts than to cost-effectiveness
analyses.

Footnotes

Editor's note: In Appendix 2 of their article (available at
www.cmaj.ca/cgi/content/full/179/11/1143/DC2 ), Bayoumi and Zaric
provide additional information on the design of their
cost-effectiveness model and how it was applied in their analysis.

Contributors: Each of the authors contributed to the content of the article,
revised it critically and approved the final version for publication.

Competing interests: None declared.

REFERENCES

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3. Des Jarlais DC, Hagan H, Friedman S, et al. Maintaining low HIV
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4. Stimson GV. AIDS and injecting drug use in the United Kingdom,
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6.Des Jarlais DC, Perlis T, Arasteh K, et al. HIV incidence among
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7. Des Jarlais DC, Perlis T, Arasteh K, et al. "Informed altruism" and
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8. Kuyper LM, Hogg R, Montaner J, et al. The cost of inaction on HIV
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9. Harris LT, Fiske S. Dehumanizing the lowest of the low. Psychol Sci
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10. Des Jarlais DC. Harm reduction - a framework for incorporating
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Related Article

The cost-effectiveness of Vancouver's supervised injection facility
Ahmed M. Bayoumi, MD MSc and Gregory S. Zaric, PhD Can. Med. Assoc. J.
2008 179: 1143-1151. http://www.cmaj.ca/cgi/content/full/179/11/1143