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December 4, 2006
Routine Testing Is Cost Effective (Reuters Health)
The recent revision in the recommended testing strategy for HIV infection in the US is cost-effective when the prevalence of HIV is above 0.2%, investigators report in the Annals of Internal Medicine for December 5.
Earlier this year, the US Centers for Disease Control and Prevention shifted their advice, from testing only high-risk individuals to routine testing of all of persons aged 13 to 64 in all healthcare settings "unless a formal survey documents the prevalence of undiagnosed HIV infection to be less than 0.1%."
Dr. A. David Paltiel, an epidemiologist at Yale School of Medicine in New Haven, Connecticut, and his team used a simulation model of HIV screening, based on published reports of HIV transmission risk, to evaluate cost-effectiveness depending on prevalence and incidence of HIV infection.
The researchers' target populations were U.S. communities with low-to-moderate prevalence of 0.05% to 1.0%, and annual HIV incidence of 0.0084% to 0.12%.
Viewed in terms of population-level effects, and assuming no effects of screening and treatment on the basic transmission scenario, they estimate that one-time testing would cost $37,100 per quality-adjusted life-year (QALY) gained. Rescreening after 5 years would raise the cost/QALY to $60,100; if testing was repeated every 3 years, it would cost $96,800.
When they assumed that secondary HIV transmission would rise after screening the whole population -- because consequent treatment might lead to longer infectious lifetimes and greater complacency about risk -- costs per QALY with one-time testing would add up to $44,200. Screening every 3 to 5 years would exceed $100,000/QALY.
"Assuming moderately favorable effects of antiretroviral therapy on transmission, cost-effectiveness ratios remained below $50,000/QALY in setting with HIV prevalence as low as 0.20% for routine HIV screening on a one-time basis and at prevalences as low as 0.45% and annual incidences as low as 0.0075% for screening every 5 years," Dr. Paltiel's team concludes.
In an editorial, Dr. Bernard M. Branson, from the CDC in Atlanta, Georgia, points out that the conclusion about cost-effectiveness "is based on the conventional premise that interventions that produce a QALY for $50,000 or less are a bargain."
He suggests that routine testing will be more cost-effective than Dr. Paltiel's group estimates.
For one thing, he says, their model includes pretest counseling, which costs 3 times more than the rapid HIV test. He suggests reserving counseling effects for patients most likely to benefit: those with positive test results and those who engage in high-risk behaviors.
He also predicts that screening would be unlikely to have detrimental effects, based on previous research showing annual transmission rates for persons unaware of their HIV infection to be 6.9%, compared with 2.0% for those who do know.
"HIV screening can bring lifesaving information to infected patients earlier, when it is most beneficial, helping them to protect themselves and their partners," he concludes. "Eventually, reminiscent of successful screening programs for syphilis and tuberculosis, the cost-effectiveness question for HIV will change from whether we should screen for HIV to when we should stop."
