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Pharmacy refills for antiretroviral drugs have advantages over T-cell counts for monitoring HIV disease progression

In the developed world, the standard of care for monitoring HIV response to antiretroviral drugs is measuring plasma HIV-1 RNA levels (viral loads). However, this approach is often unavailable in the developing world. The World Health Organization recommends monitoring patients with HIV disease in resource-limited countries with CD4 T-cell counts, which decline as HIV disease progresses. However, a less expensive way to monitor the effectiveness of first-line combination antiretroviral therapy (cART) may be pharmacy refill adherence, suggests a new study.

Researchers found that this adherence predicted virologic failure (HIV load more than 1,000 copies/ml of blood), whereas CD4 counts simply detected current virologic failure. This is important because if virologic failure has already happened, patients have to be switched to the more expensive second-line cART.

Researchers at the University of Pennsylvania School of Medicine Center for Education and Research on Therapeutics and colleagues examined cART pharmacy refill adherence, CD4 count changes, and virologic failure among 1,982 HIV-infected adults in an AIDS disease management program in 9 southern African countries. These patients were assessed either 6 or 12 months after cART initiation and after a previous undetectable viral load (less than 400 copies/ml of blood).

Pharmacy refill adherence and CD4 counts were equally accurate in detecting current breakthrough viremia (increase in viral load to detectable levels of 400 copies/ml of blood). Adherence levels assessed 3 months prior to viral load assessments were as accurate for virologic failure occurring about 3 months later as were CD4 count changes calculated from cART initiation to the actual time of the viral load assessments. This indicates the potential usefulness of pharmacy refill adherence to predict virologic failure before it occurs, rather than afterwards, which is indicated by CD4 counts.

The study was supported in part by a grant (HS10399) from the Agency for Healthcare Research and Quality to the University of Pennsylvania School of Medicine Center for Education and Research on Therapeutics (CERT). For more information on the CERT program, please visit http://www.ahrq.gov See "Pharmacy refill adherence compared with CD4 count changes for monitoring HIV-infected adults on antiretroviral therapy," by Gregory P. Bisson, M.D., M.S.C.E., Robert Gross, M.D., M.S.C.E., Scarlett Bellamy, Sc.D., and others, in the May 2008 PLoS Medicine 5(5), pp. 777-789.

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