New Study Identifies Most Beneficial Age for One-Time HIV Screening Test

HIV infections and diagnoses have been on the decline overall in the United States in part thanks to improved testing and screening for the virus. Now, following a recent study, researchers have managed to pinpoint the optimal age when all young adults should be tested for HIV.

According to the Centers for Disease Control and Prevention (CDC), there are about 1.1 million individuals in the United States living with HIV, which includes an estimated 166,000 individuals who do not know they are infected. Making sure that HIV-positive individuals know their status is important to the public health goal of preventing the spread of the virus, as about 30% of new HIV infections are transmitted by those who have not been diagnosed. The HIV tests most commonly used check the blood for antibodies to HIV, or for the antigens which activate the immune response to the virus. Since 2006, the CDC has recommended that everyone between the ages of 13 and 64 get tested for HIV at least once as part of routine health care, regardless of risk factors. Early symptoms can include flu-like illness occurring 2 to 4 weeks after infection, while individuals in the later stage of infection can go on to develop AIDS and are prone to severe illness. However, in screening, individuals are tested even if they don’t have any symptoms associated with HIV.

In a new study published in the Journal of Adolescent Health, researchers from Massachusetts General Hospital in Boston aimed to figure out the best age at which HIV screening should occur. They note that while there are about 61,000 individuals between the ages of 13 and 24 living with HIV in the United States, an estimated 51% of those adolescents and young adults who are infected are not aware of their status. In 2012, only 13% of US high school students reported being screened for the virus, and screening among ages 18 to 24 declined from 2000 to 2010; just 30% of this age group reported ever being screened for HIV. The authors stress that individuals unaware of potential HIV infection miss the opportunity to begin needed antiretroviral therapy (ART) during the early stages of the infection; not only can ART potentially prevent disease progression, but it can prolong life for decades.

Hypothesizing that a one-time screen at a younger age could miss infections that may occur later in life, the researchers decided to look at CDC data regarding new HIV diagnoses made in 2013 using a computer simulation model. Simulating HIV-uninfected 12-year-olds without risk factors in the United States, the team evaluated the cost-effectiveness of alternative strategies for routine one-time HIV screening at 15, 18, 21, 25, or 30 years of age. "We began by thinking that, if people are screened only once, it makes sense to get screened after the age when the most new HIV infections occur,” said study lead author Anne Neilan, MD, MPH., in a recent press release. “We also thought that, if we accounted for all of the HIV testing that is already taking place in the United States, an additional screening test for youth without known risk factors would be most useful at some point after age 18."

The team found that screening for HIV at age 25 would lead to better HIV diagnosis rates and overall health outcomes among young adults. While the authors note that most new HIV infections occur after age 25 — and that a screen at that age would only detect 13% of all lifetime infections – the simulation found that screening at 25 led to the most favorable care continuum outcomes, with 77.3% diagnosed, 70.8% linked to care, 61.5% retained in care, and 51.4% virologically-suppressed.

"For at-risk groups, HIV screening should occur much more frequently than once in a lifetime, since a single screen will only capture a very small proportion of the population with HIV,” pointed out senior author Andrea Ciaranello, MD, MPH. “However, for young people who become infected by age 25, the gains in life expectancy and improvements in health outcomes, including viral suppression, from that one-time screening test would be substantial."