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Making HIV Testing Cost-Effective

A new analysis illustrates the complexities of constructing rational policies for routine HIV testing.

Physicians who care for patients at high risk for HIV infection have long been accustomed to screening them periodically. Now that HIV tests are on their way to becoming routine, however, all physicians will need sensible guidelines for using the tests wisely. A cost-effectiveness analysis teases out some important parameters for constructing such guidelines.

Researchers in the U.S. assembled a set of standard assumptions about the cost of HIV testing ($7 for a rapid test, $40 for confirmatory testing), the success of antiretroviral treatment in reducing viral load to undetectable levels within 48 weeks (80% success for a first regimen, less for subsequent regimens), and the likelihood of treatment to lower the cost of HIV-related complications.

Looking only at the health of the individuals tested, researchers found that a single rapid screen of all adults would cost society $37,100 per quality-adjusted life-year (QALY) gained. Testing every 3 years would cost $96,800 per QALY gained and would be as effective as annual testing. If early HIV detection and treatment were assumed to lower the rate of secondary HIV infections (by reducing the infectivity of the index case), these costs were reduced. However, if early detection and treatment were assumed to increase secondary infections (by extending the lifespan of infected persons), the costs were increased. The cost-effectiveness of mass testing was improved with higher baseline HIV incidence and prevalence and with less nonroutine, "background" HIV testing (e.g., testing in correctional institutions or for employment purposes).

The bottom line of the analysis: In areas where the prevalence of undiagnosed HIV infection exceeds 0.20%, single rapid HIV screening was as cost-effective as most other currently recommended screening tools for chronic disease. Recommended intervals for repeat screening depended on local incidence rates. For example, screening a population every 5 years was cost-effective in places with an HIV prevalence of at least 0.45% and an annual incidence of at least 0.0075%.

Comment: This analysis has very few practical applications. Physicians rarely know the precise HIV incidence and prevalence figures for their own communities, and even policy-making organizations are unlikely to have precise information on exactly where the high-prevalence pockets of infection lie. However, the study does give us a good idea of how difficult the construction of rational HIV testing policies is likely to be. Fortunately, testing decisions are far simpler in the care of individual patients than on a large scale, and one hopes that any future policies will be elastic enough to incorporate all small-scale decision making.

— Abigail Zuger, MD

Published in AIDS Clinical Care December 11, 2006

Citation(s):

Paltiel AD et al. Expanded HIV screening in the United States: Effect on clinical outcomes, HIV transmission, and costs. Ann Intern Med 2006 Dec 5; 145:797-806.

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