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

Early identification of treatment failure among human immunodeficiency viru s (HIV) type 1-infected patients receiving antiretroviral therapy could ena ble clinicians to modify inadequate regimens and to improve treatment respo nse. 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 clin ical trials. The approach assumed 2 patterns of HIV-1 response: "on track," for eventual suppression to HIV-1 RNA levels below the limit of quantifica tion, and "off track," for deviation from this response. The results of thi s on- or off-track classification generally agreed with the protocol-define d outcomes of virologic success and failure, thus validating these commonly used definitions. Overall, only a minority of patients went off track beca use of suboptimal HIV-1 RNA response by the first follow-up visit. Most pat ients who went off track did so at later time points and had sharp unexpect ed rebounds without prior indication of a suboptimal response.