Thursday, February 10, 2005

Routine HIV Screening Should Be Expanded
By Richard Merritt, Duke Medical Center News Office

DURHAM, N.C. -- A new cost-effectiveness analysis has led researchers from Duke University Medical Center and the Veterans Affairs (VA) Palo Alto Health Care System to recommend that routine voluntary screening for HIV, the virus that causes acquired immune deficiency syndrome (AIDS), should be expanded well beyond current guidelines to include health care settings where the incidence of the virus would be expected to be low.

These include such settings as outpatient clinics, urgent care clinics or emergency rooms in areas that have in the past been deemed low-risk for HIV. The researchers recommended expanded testing because of the success over the past decade of highly active antiretroviral therapy (HAART) in prolonging the quantity and quality of lives of patients infected with AIDS, as well as decreasing the rate at which those infected with the virus can transmit the disease to others.

HAART therapy involves using multiple drugs, all of which block replication of HIV genes. For most patients, these drugs combinations have reduced the viral load in the blood to virtually undetectable levels. Not only has this therapy increased the life expectancies of infected patients, but researchers believe that HAART also reduces their infectivity.

The results of the cost-effectiveness analysis were published Feb. 10, 2005, in the New England Journal of Medicine.

Gillian Sanders, Ph.D.

"Past cost-effectiveness studies of HIV screening were conducted before the advent of HAART, a treatment regiment that has made AIDS a chronic disorder with much longer life expectancies," Sanders said. "Our study's results should provide the medical community, health care administrators and policy-makers with the data they need to expand screening."

Sanders' paper is being published alongside a study from researchers at Yale and Harvard with similar results. "These two independent studies provide great external validation for each other – emphasizing the robustness of our findings and the value of expanded HIV screening," she said.

Sanders led the study with colleagues from the Palo Alto (Calif) VA Health Care System, Stanford University, and St. Michael's Hospital, Toronto. The study was funded by the Department of Veterans Affairs Research and Development Service, the Ontario HIV Treatment Network and the National Institute of Drug Abuse.

For their analysis, the team used a model that accounts for a wide variety of variables, including patient characteristics, the natural history of the disease, the timing of testing and treatments, immunological status, outcomes, medical costs, and quality of life parameters. The data used for the model were drawn from the latest clinical trial results and studies published in the scientific literature.

The model targeted patients who were unaware of their HIV status when they entered the health care system, whether at a hospital, clinic, routine medical or emergency room visit. The model then calculated the incremental costs and benefits across the lifetime of typical patients. As a part of their analysis, the researchers assessed the cost-effectiveness with and without considering the benefits to the sexual partners of the patients.

In the U.S., the commonly accepted threshold for the cost-effectiveness of medical therapies is $50,000 per quality-adjusted life-year gained. A cost-effectiveness ratio below $50,000 is usually considered cost-effective and the treatment would be considered good value for the money. In these analyses, researchers not only include the potential medication, hospitalization and other medical costs, but also take into account quality-of-life benefits patients receive for their added life expectancies.

When the researchers considered a screening program in which the prevalence of unidentified HIV infection was one percent, the model found an increase in life expectancy of about 1.5 years for patients infected with HIV, costing $41,736 per quality-adjusted life-year gained compared to current practice. When the costs and benefits to the partner were included in the model, the cost-effectiveness of screening became even more favorable with an incremental cost effectiveness of $15,078 per quality-adjusted life-year.

"Additionally, the model showed that the prevalence of HIV can be as low as 0.5 percent and still remain below the $50,000 per quality-adjusted life-year threshold," Sanders continued. "When you then include the costs and benefits to partners, the prevalence can go as low as 0.05 percent before reaching the $50,000 threshold.

"These findings suggest that routine screening is likely to be cost-effective at a substantially lower prevalence than previously recognized," Sanders said. "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."

Expanding the scope of routine HIV screening is important, the researchers said, because patients can be infected, as well as infectious, for many years before they start showing symptoms of the disease.

"Recent data from the CDC has shown that for 41 percent of HIV-infected patients in the U.S., symptoms of AIDS develop within a year of diagnosis, suggesting that opportunities to reduce risk behaviors or initiate early treatment had been missed," Sanders said.

Sander also cited a recent study of blood samples from outpatient clinics from six different Veterans Affairs Medical Centers (VAMC) systems that found a range of 0.13 to 2.9 percent of patients with undiagnosed HIV. Many outpatient settings do not routinely offer HIV screenings, though the current analysis would suggest that it would both increase life expectancy and be cost-effective, Sanders said.

Joining Sanders in the analysis, from the Palo Alto VA Health Care System, were Vandana Sundaram M.P.H, Lena Douglass, Mark Holodniy, M.D., and Douglas Owens, M.D. Other team members included Ahmed Bayoumi, M.D., from University of Toronto and S. Pinar Bilir, Christopher Neukermans, Chara Rydzak, and Laura Lazzeroni, Ph.D. from Stanford.