Authors' reply

Abstract

We thank Duncan Smith-Rohrberg and colleagues and Stephen Lawn and co-workers for their comments concerning our algorithm and their pledge for the availability of more viral load testing in resource-limited settings. For the moment however we have to confront the reality faced by most countries struggling with antiretroviral treatment scale-up: viral load testing remains expensive requires a well-equipped laboratory well-trained personnel and is not available in most resource-limited settings. For these reasons WHO is still not recommending viral load tests for regular monitoring of antiretroviral treatment in resource-limited settings. Two randomised trials in Africa--the Centers for Disease Control and Prevention (CDC) study in Tororo Uganda and the Development of Antiretroviral Therapy in Africa (DART) study in Uganda and Zimbabwe--were initiated in 2004 comparing clinical monitoring only with clinical and routine laboratory monitoring. Both studies are still ongoing meaning the data safety monitoring boards have not stopped them because patients in the laboratory arm were doing better than patients in the clinical monitoring only arm. However it is unlikely that these studies will provide a definite answer concerning the value of viral load testing to monitor antiretroviral therapy in resource-limited settings. Indeed viral load testing is only done in one of the three study arms in the CDC Tororo study. Moreover the primary outcomes of both studies are the development of an AIDS-defining illness or death and not drug resistance a marker that may teach us more about the long-term outcome of the antiretroviral therapy. (excerpt)