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May 28, 2008

Pain-Free, Accurate and Low-Cost Tool Predicts Antiretroviral Treatment Failure in HIV Patients

Jean Nachega, MD, MPH

Monitoring an HIV patient’s antiviral drug prescription refills may be an efficient, blood-free way to reliably predict whether a patient's treatment will succeed or fail. In a study published in the May 2008 issue of PLoS Medicine, researchers from the University of Pennsylvania School of Medicine, the Johns Hopkins Bloomberg School of Public Health and the University of Cape Town determined that prescription refill adherence was more accurate than CD4 count monitoring as a predictor of virologic failure. Virologic failure occurs when treatment is no longer able to suppress multiplication of the virus.

Successful adherence in developed countries is usually confirmed by blood tests, or viral load tests, that assess how well the treatments are fighting the AIDS virus. However, these tests are often not easily accessible or affordable in developing countries. In such settings, the current WHO guidelines recommend that doctors and program workers use alternative measures such as CD4 counts that shed light on the immune system's response to the treatment. The drawback of this test is that declining CD4 counts usually indicate that the treatment is failing and the virus has already developed resistance. At this point, the medications need to be changed—usually to drugs that are more expensive or difficult to take.  Researchers acknowledge these guidelines do not emphasize the importance of using adherence monitoring in the decision making process. These data suggest that current guidelines for monitoring HIV treatment in resource-limited settings should be revised.

“After combination antiretroviral therapy initiation, adherence levels outperformed CD4 count changes when used to detect current virologic failure in the first year,” said Jean Nachega, MD, MPH, senior author of the study and associate scientist at the Bloomberg School of Public Health’s Department of International Health. “When monitoring pharmacy refill adherence in addition to CD4 counts, health care professionals were able to predict virologic failure earlier than when using CD4 counts alone.”

Gregory Bisson, MD, assistant professor at the University of Pennsylvania School of Medicine, along with Nachega and several colleagues conducted an observational cohort study of 1,982 adults over the age of 18.  The participants, spanning nine countries, were part of the Aid for AIDS Disease Management Program in South Africa. Researchers monitored the number of monthly prescription claims compared to medications dispensed to patients, as well as CD4 count changes, to determine accuracy in predicting current and future virologic failure.

The researchers found that by predicting virologic failure earlier health care professionals can minimize costs while providing optimal care for individuals. “Antiretroviral therapy regimens prescribed in response to virologic failure are often more complex poorly tolerated therapies and may require even higher levels of adherence to maintain viral suppression,” Nachega said. “Maximizing the benefit of initial antiretroviral therapy is critical, especially in developing countries where resources and treatment options are limited.”

“Our results support a real paradigm shift in the way HIV treatment is monitored by providing evidence that the focus should be on proactive continuous monitoring of adherence, using a simple, reliable, low-cost validated adherence tool such as pharmacy refill instead of solely monitoring CD4 counts,” said Nachega. “The goal is to intervene before the virus is able to replicate and develop resistance mutations.” –-Natalie Wood-Wright

Public Affairs media contact: Natalie Wood-Wright at 410-614-6029 or