September 30, 2009

Adherence Required to Keep Viral Load Undetectable May Decline Over Time

The perceived risk of virologic failure associated with less-than-perfect adherence may be lower after successfully keeping viral load undetectable while on antiretroviral (ARV) treatment for at least a year, according to a study published September 29 in the online journal PLoS One. However, the study authors stress that the goal of strict adherence for as long as someone remains on HV therapy remains unchanged.

Though seriously potent, ARV treatment has a major Achilles’ heel—the virus can easily develop resistant to the drugs if they aren’t taken on time as prescribed every day. Previous estimates of the older drugs found that people shouldn’t miss more than one dose per month if they were on a once-daily regimen. Though some researchers have said they think the newest drugs might be a tad more forgiving than that, they still argue that high levels of adherence are key to long-term treatment success.

Some researchers, however, including Michael Rosenblum, PhD, from the University of California at San Francisco, and his colleagues have suspected that the need for near-perfect adherence might decrease the longer a person successfully maintained very low levels of HIV. To test this theory, his team looked at the link between adherence and treatment failure in 221 HIV-positive people who were marginally housed in San Francisco. Adherence was assessed through unannounced visits to the participants’ residences. Viral suppression was defined as maintaining a viral load of less than 50 copies, and treatment failure was defined as having a viral load of more than 50 copies.

It turned out that the researchers’ hunch was correct. The longer a person maintained viral suppression, the less that adherence factored into treatment failure. In people who were adherent 50 to 74 percent of the time, the percentage of people experiencing treatment failure plummeted from 49 percent after one month of viral suppression to just 2 percent after a full year of viral suppression. When adherence was 75 percent or more, similar drops in the risk for treatment failure occurred after 12 months of viral suppression.

Though the authors concede that the results of their study paint a more promising picture than in the past, in terms of the forgiveness of current ARV regimens, they argue that high levels of adherence should still be a top priority for people with HIV to ensure long-term treatment success.

Search: Adherence, antiretroviral therapy, Michael Rosenblum, partial adherence, viral suppression, treatment failure

Scroll down to comment on this story.

Previous Comments:

Dr. John D., DC, 2009-10-01 12:50:03
This report offers some comfort when an occasional dose is missed. It does NOT however endorse missing doses of ARVs. The best defense against developing resistance is to not miss any doses of your meds. If I can be 100% adherent for 6 years so can you.