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Routine
HIV Antibody Testing Is Cost Effective Even in Low Prevalence Populations
By Karla Gale
Routine
screening for HIV would be a cost-effective measure compared with
screening targeted at symptomatic patients, even in populations
with relatively low prevalence
of the disease, according to two separate reports in the New
England Journal of Medicine for February 10, 2005.
The
Centers for Disease Control and Prevention (CDC) currently recommends
routine screening rather than targeted screening in populations
where the prevalence of HIV exceeds 1%.
However,
current approaches to testing
are inadequate, Dr. Gillian D. Sanders, at Duke University in Durham,
North Carolina, and her team suggest, since many patients have advanced
disease by the time they are identified.
Dr.
Sanders' team used a Markov model to estimate costs of one-time
routine screening in a healthcare setting, using ELISA
testing followed by Western blotting.
In
a population with a 1% prevalence of unidentified HIV, routine screening
would result in an increase in life expectancy of the HIV-infected
patient of 1.52 years compared with symptom-based case finding,
the authors report. The associated cost would be $41,736 per quality-adjusted
life year (QALY) gained -- less than the $50,000 per QALY that is
the commonly accepted threshold for the cost-effectiveness of healthcare
interventions.
Screening
would result in reduced costs and benefits to sexual partners, as
rates
of transmission would drop by about 20% because of reduced
infectivity resulting from treatment with antiretroviral agents
and decreased risk behaviors. Taking this into account, the investigators
estimate that routine testing would involve an incremental cost-effectiveness
of $15,078 per QALY.
In
this analysis, the prevalence of unidentified HIV can be as low
as 0.05% before it would exceed $50,000. The prevalence in the general
US population is estimated to be 0.1%
"We
believe that in many different health care settings, routine HIV
screening can provide important health benefits for a reasonable
investment in health care resources," Dr. Sanders comments
in a Duke University press release.
In
the second report, Dr. A. David Paltiel, at Yale School of Medicine
in New Haven, Connecticut, developed a mathematical simulation model
of HIV disease.
In
a high-risk population (prevalence, 3.0%), one-time screening would
cost $36,000 per QALY compared with targeted testing. In the CDC
threshold population (prevalence, 1.0%), the cost-effectiveness
ratio rises to $38,000 per QALY. And at a prevalence of 0.1%, they
estimate the cost would amount to $113,000 per QALY.
"Our
sensitivity analysis shows that even minimal therapy-related improvements
in viral load and risk behaviors could reduce secondary infections
and produce substantially more favorable cost-effectiveness ratios,"
Dr. Paltiel's group points out.
In
a related editorial, Dr. Samuel A. Bozzette, from the University
of California, San Diego, comments that "the credibility of
these authors' conclusions is greatly enhanced by the similarity
of findings from the two different models."
Because
these models do not incorporate secondary benefits of screening,
such as reduced productivity loss and indirect costs of HIV disease,
he adds, "the true economic costs of screening are far lower
than reflected by direct expenditures."
02/14/05
N
Engl J Med 2005;352:570-595,620-621.
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