Expanded HIV Screening and Treatment Could Prevent More than 200,000 New Infections

One-time HIV screening of the entire adult population plus annual screening of people at higher risk could prevent nearly 7% of projected new infections, while treating more eligible people with antiretroviral therapy (ART) could raise the proportion of averted infections to about 17%, according to research described in the December 21, 2010, Annals of Internal Medicine. Investigators estimated that the cost of the combined strategy would be about $21,500 per year of life saved.

It is well known that HIV treatment lowers viral load and consequently decreases the likelihood of passing on the virus through sex or needle sharing. HIV screening enables people to start ART in a timely manner, and studies also show that when people learn their status, they typically reduce risky behavior that could transmit the virus to other.

Public health experts have called for expanding HIV screening and treatment -- perhaps even for all HIV positive people regardless of CD4 T-cell count -- as part of a comprehensive approach to prevention.

Adding to the body of mathematical models estimating the effects of "test-and-treat," Elisa Long from Yale School of Management and colleagues looked at how expanded screening, wider use of ART, and interventions to reduce risk behavior might affect the U.S. epidemic.

The researchers constructed a dynamic mathematical model of HIV transmission and disease progression, as well as a cost-effectiveness analysis, using data from published medical literature.

They focused on 2 target populations, one high-risk (injection drug users and men who have sex with men [MSM]), the other low-risk (everyone age 15 to 64 years), over 2 time horizons, 20 years or lifetime. They estimated costs and benefits based on quality-adjusted life-years (QALYs), a measure of survival that takes into account quality of life.


Based on these findings, the study authors concluded, "Expanding HIV screening and treatment simultaneously offers the greatest health benefit and is cost-effective."

Importantly, this model did not look at the more controversial approach of treating everyone diagnosed as HIV positive, but rather treating symptomatic people and those with a CD4 count below 350 cells/mm3, the threshold in the previous U.S. ART guidelines -- now raised to 500 cells/mm3.

However, the researchers added, "even substantial expansion of HIV screening and treatment programs is not sufficient to markedly reduce the U.S. HIV epidemic without substantial reductions in risk behavior."

"[O]ur analysis highlights the importance of emphasizing risk behavior reduction as HIV screening and treatment becomes increasingly available," they elaborated in their discussion. "For example, in addition to expanded screening and treatment, a 50% reduction in sexual risk behaviors among MSM and needle sharing among injection drug users could prevent 65% of new infections, reducing HIV incidence to approximately 20 000 cases per year. This suggests that programs to reduce risk behavior among high-risk persons will probably be a key component of a successful prevention program. If, however, uninfected persons increase risk behavior after screening, some of the benefits would be attenuated."

Finally, they noted, "Compared with other disease screening programs in the U.S., 1-time HIV screening of low-risk persons and annual screening of high-risk persons is economically attractive, with a cost-effectiveness ratio less than $23,000 per QALY gained. This compares favorably with other accepted interventions, including screening for type 2 diabetes and breast cancer mammography."

Investigator affiliations: Yale School of Management, New Haven, CT; Stanford University, Stanford, CA; Veterans Affairs Palo Alto Health Care System, Palo Alto, CA.



E Long, ML Brandeau, and DK Owens. The cost-effectiveness and population outcomes of expanded HIV screening and antiretroviral treatment in the United States. Annals of Internal Medicine 153(12): 778-789 (Abstract). December 21, 2010.

Other Source

M Fox. Better HIV screening worthwhile in U.S., study finds: 'one-time screening of all adults would prevent 81,000 HIV-infections.' Reuters Health. December 20, 2010.