New testing strategy to help track HIV
Detuned testing initiated at 24 sentinel sites
The Centers for Disease Control and Prevention (CDC) is moving quickly to monitor HIV incidence across the country using its "detuned" testing technology, with nearly $6 million this year committed to 24 sentinel cities.
And while the CDC’s test doesn’t meet Food and Drug Administration (FDA) criteria for use as a clinical test, the private sector is showing increased interest in the potential market for a commercial test, particularly in developing countries.
"This initiative is the single most important new direction for the CDC," says Ward Cates, MD, MPH, president of Family Health International in Research Triangle Park, NC, and a CDC advisor. "We have to know where the incidence is going and the sooner we can drive resources from measuring old infections to new infections, the better off we will be."
With the advent of highly active antiretroviral therapy, CDC surveillance has lost its edge in following the HIV epidemic as the time gap between HIV infection and progression to AIDS has grown increasingly wide. While HIV reporting is required in most states, some of the most populous states still report only AIDS cases, giving the CDC an incomplete picture of trends in new infections.
To solve that problem, the CDC created the Serological Testing Algorithm for Recent HIV Seroconversion or STARHS. The algorithm is based on the simple idea that antibodies to HIV rise through the period of infection. The "detuned" test allows researchers to identify newly infected people — within four to six months — with a fairly high degree of sensitivity.
Developed several years ago, the detuned assay has been used in small cohort studies, most notably the Young Men’s Survey, which found high rates of new infections, particularly in African-American males who have sex with males. Since 2001, the CDC has been working to make STARHS its strategy for monitoring HIV incidence across the country.
After numerous consultations, the CDC funded five demonstration sites to develop protocols and explore methodologies for integrating the detuned technology into HIV surveillance activities. The technical issues are complex and involve not only testing specimens but collecting data on testing histories. To enable statisticians to estimate HIV incidence in the general population, information is needed on how often people are tested for HIV.
"We need a statistical system based on how frequently people are tested in order to come up with viable estimates," says Matthew McKenna, MD, director of the CDC’s HIV Incidence and Case Surveillance Branch.
The 24 sites were selected based on having HIV reporting in place prior to January 2001 and having greater than 300 AIDS cases per year. Setting up STARHS in all 50 states would be too expensive, McKenna adds.
From input gathered from the sites, it has become clear that flexibility is important, as "different places will want to do this in different ways," he says.
The CDC test, which is sensitive only to HIV-1 subtype B, could be a useful tool for U.S. clinicians. However, diagnostic companies don’t see a large enough market in this country. "We don’t know of any manufacturer who is going to step up to the plate and do all the necessary studies and paperwork to satisfy FDA approval for clinical use," McKenna says.
However, several tests are being developed that capture other subtypes and would have broader applications. One test looks at specific antibody isotopes instead of just antibodies alone. "The interest has become so intense, not so much in the United States but globally, that we are optimistic some manufacturers may be interested in it," he adds.
Several consent issues surrounding STARHS must be worked out. One of the more sticky ones is whether results from detuned testing can be given back to patients.
The testing program is considered a non-research activity. While knowing when a patient was infected could have clinical value, especially for treatment considerations, providing that information would put the program into the "research" category.
"Right now the FDA is adamant that giving back test results constitutes research, and that would mean setting up IRBs [institutional review boards] and getting consent," McKenna explained.
The IRB process ensures the protection of human subjects in CDC research.
The CDC officially defines research as "a systematic investigation, including research development, testing, and evaluation, designed to contribute to generalizable knowledge."
The Centers for Disease Control and Prevention (CDC) is moving quickly to monitor HIV incidence across the country using its detuned testing technology, with nearly $6 million this year committed to 24 sentinel cities.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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