OTTAWA - A federal government threat to close Vancouver's supervised injection facility appears to be based more on emotion than rational analysis, says a new study.

The HIV rate among injection drug users could double without the controversial facility known as Insite, says the report in this week's Canadian Medical Association Journal.

And it predicts the facility will save health-care dollars if federal exemptions that allow it to operate are maintained.

"Insite is likely to be cost-effective," says the study by three American PhDs. "The threat to close Insite appears to be based more on emotional reactions to the facility and drug addicts than to cost-effectiveness analyses."

The federal Conservative government wants Insite closed and is appealing a recent British Columbia Supreme Court decision that struck down some drug laws because they could prevent Insite from operating legally.

The decision gave Ottawa until June 30 to bring the Controlled Drugs and Substances Act in line with the Charter of Rights and Freedoms. It also gave Insite an immediate constitutional exemption to stay open.

Former health minister Tony Clement repeatedly criticized Insite, saying it facilitates addiction and questioning the ethics of doctors who support the facility, which opened in 2003 under a special exemption from federal drug laws.

But the medical journal report says estimates of future incidence rates of HIV among injection-drug users in Vancouver vary greatly, depending on efforts to prevent the infection.

"Although randomized controlled trials have not been possible, the research has indicated substantial public health benefits associated with the facility's operation," said the study.

The authors were Don Des Jarlais and Kamyar Arasteh of New York's Beth Israel Medical Center, and Holly Hagan of the National Development and Research Institutes in New York.

The HIV incidence rate among injection drug users in New York City fell to one per 100 person-years from four after large-scale expansion of needle-exchange programs, the study says.

It estimates the incidence of HIV infection among needle-users in Vancouver would be between four and five per 100 person-years without Insite.

"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," it says.

"With allowances for growth in the population of injection drug users over time, this would equal about 250-350 averted infections over 10 years."

With an estimated lifetime medical expense of $150,000 to treat HIV, Insite would be a cost-saving venture even if it prevented only a modest number of HIV infections each year, the study says.

"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," it says.

"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."

The authors quoted other studies to support their contention that decision-making about controversial public health projects such as Insite may 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."

Almost any intervention that reduces the incidence of HIV infection in a developed country such as Canada is likely to be cost-effective, the study says.