Challenges in implementing HIV laboratory monitoring in resource-constrained settings: how to do more with less.

Laboratory monitoring for HIV disease in resource-limited settings has now become one of the key challenges for antiretroviral treatment (ART) access and success, as emphasized by the 2010 revised WHO guidelines for ART in resource-limited settings. Thus, the most common method for initiating ART, and monitoring treatment response in resource-constrained environments is the measurement of CD4 T-cell count. Affordable CD4 T-cell counting has gradually been made possible by using simple, compact and robust, low-cost, new-generation cytometers, operating as single-platform volumetric instruments. Several cost-effective point-of-care CD4 T-cell testing options are also already on the market, in order to improve access to CD4 T-cell monitoring, especially for rural patients, and to reduce loss-to-follow-up of patients. In addition, HIV RNA viral load measurement is becoming increasingly important, mainly for a systematic confirmation of first-line ART failure before switching to second-line treatment to avoid belated as well as premature therapeutic decisions and their potentially negative consequences. Viral load testing should now be considered as the standard of care for therapeutic failure in all resource-limited settings. However, the measurement of HIV viral load remains a centralized marker, carried out in a limited number of reference laboratories. Finally, the costs of second-line ART regimens, rather than the laboratory test costs themselves, currently constitute the primary determinant of the total cost in ART switching. Laboratory monitoring strategies may become more attractive as price negotiations render second-line ART regimens less expensive worldwide.