Routine HIV Screening Called Cost-Effective

NEW HAVEN, Conn., Dec. 6 -- All adults in the U.S. should be routinely given a rapid test for HIV unless there's evidence that local prevalence of undiagnosed infection is less than 0.2%, suggest researchers here.

The recommendation, derived from a simulation model, is strong support for this summer's call by the CDC for expanded routine HIV screening, reported David Paltiel, Ph.D., of Yale, and colleagues, in the Dec. 5 issue of Annals of Internal Medicine.

The CDC suggested that Americans ages 13 to 64 should be routinely tested for HIV in all health-care settings, unless a formal survey showed local prevalence of undiagnosed HIV to be less than 0.1%, wrote Dr. Paltiel and colleagues.

The new model suggests a slightly higher threshold, the researchers said, but otherwise "entirely supports the shift from targeted screening based on patient risk factors to routine screening."

Under a range of assumptions, Dr. Paltiel said, the model suggests that rapid routine testing for HIV can be cost-effective, as measured by the dollar cost for quality-adjusted life-year (QALY), a standard measure in health economics studies.

"HIV screening delivers better value than many other diagnostic tests and treatments that physicians use routinely in daily practice, including screening for breast cancer, colorectal cancer, diabetes and hypertension," Dr. Paltiel said.

But he and colleagues cautioned that the results of their study hinge on a key assumption -- that people whose HIV infections are caught by routine screening will receive current state-of-the-art care.

"There is no point searching for needles in haystacks if you merely plan to throw them back in," Dr. Paltiel said. "The CDC's commitment to expanded HIV screening must be accompanied by an equally bold financial commitment from the state and federal agencies that provide and pay for HIV care."

An intervention is conventionally deemed to be cost-effective if the cost per QALY is ,000 or less, the researchers said.

Dr. Paltiel and colleagues found that routine screening in a population with an HIV prevalence of 1.0% and an annual incidence of 0.12% had incremental cost-effectiveness ratios of:

• ,800 per QALY, for one-time screening.
• ,300 per QALY, for screening every five years.
• And ,500 per QALY for screening every three years.

The finding uses what the researchers called "moderately favorable assumptions" about the effect of patient care on secondary HIV transmission.

If earlier diagnosis, combined with antiretroviral care, reduces transmission, the researchers concluded, one-time routine rapid testing is cost-effective when the prevalence of undiagnosed HIV is as low as 0.2%.

Indeed, the practice remains cost-effective even if subsequent transmission is not markedly reduced, the researchers found, but only at a higher prevalence of 0.4%.

The findings are encouraging, but may understate the benefits of screening, said Bernard Branson, M.D., of the CDC, writing in an accompanying editorial.

For instance, Dr. Branson said, many people newly diagnosed with HIV take immediate steps to protect their partners from infection, although the extent of the effect isn't known precisely.

Indeed, he said, many of the parameters needed to guide testing "will be known with certainty only after we implement screening and examine the results."

The authors recognized the difficulty practitioners would have in determining whether the local prevalence of undiagnosed HIV infection exceeded a recommended threshold. They therefore recommended "that providers initiate routine, voluntary HIV screening for all adults in the U.S., unless surveillance data in their particular setting, or in similar settings, show an HIV prevalence below 0.2%."

The study was supported by the National Institutes of Health, the CDC, and the Doris Duke Charitable Foundation.