Patterns of plasma human immunodeficiency virus type 1 RNA response to antiretroviral therapy.

Early identification of treatment failure among human immunodeficiency virus (HIV) type 1--infected patients receiving antiretroviral therapy could enable clinicians to modify inadequate regimens and to improve treatment response. Clinical definitions of treatment failure, however, may not be ideally suited for this purpose. This study empirically characterizes the patterns of HIV-1 RNA response to antiretroviral therapy in patients in 4 AIDS clinical trials. The approach assumed 2 patterns of HIV-1 response: "on track," for eventual suppression to HIV-1 RNA levels below the limit of quantification, and "off track," for deviation from this response. The results of this on- or off-track classification generally agreed with the protocol-defined outcomes of virologic success and failure, thus validating these commonly used definitions. Overall, only a minority of patients went off track because of suboptimal HIV-1 RNA response by the first follow-up visit. Most patients who went off track did so at later time points and had sharp unexpected rebounds without prior indication of a suboptimal response.