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Evaluation of the treatment-experienced patient failing HIV therapy

Eric S Daar, MD
Section Editor
John G Bartlett, MD
Deputy Editor
Jennifer Mitty, MD, MPH


The goal of antiretroviral therapy is to suppress the plasma HIV RNA below the limits of assay detection (<20 to 75 copies/mL depending upon the assay used). Suppressing the viral load prevents the emergence of drug-resistant virus and disease progression [1,2]. However, certain HIV-infected patients will experience virologic failure on their antiretroviral regimen. Such individuals require a detailed evaluation to determine the reason for failure and the best approach to achieve viral suppression.

The evaluation of the patient failing their antiretroviral regimen will be reviewed here. Selecting a new regimen is discussed elsewhere. (See "Selecting an antiretroviral regimen for treatment-experienced HIV-infected patients who are failing therapy".)


For individuals starting a new regimen, virologic failure is defined as the inability to achieve a viral load <200 copies/mL within 24 weeks of initiating antiretroviral therapy. For individuals who were initially able to suppress their viral load, virologic failure is defined as a recurrence of viremia to >200 copies/mL on two consecutive measurements taken approximately one month apart [3,4].

In contrast, intermittent "blips" of low level viremia (20 to 200 copies/mL) are generally not associated with the emergence of drug-resistant virus; thus, intermittent viral blips should not prompt a change in therapy [5]. The clinical significance and management of persistent viremia in the range of 50 to 200 copies/mL is less clear. We generally continue the current regimen with counseling to enhance adherence and to avoid drug-drug and drug-food interactions. However, in some cases (eg, patients who have continued difficulty adhering to a daily regimen), we change to a pharmacologically-boosted protease inhibitor (PI) if they are not already on this class of drugs, to minimize the risk of emerging resistance. (See 'Assess medication adherence' below.)


Virologic failure typically results from poor adherence to an antiretroviral therapy (ART) regimen, or from drug-drug or drug-food interactions that impair absorption. Patients with virologic failure may or may not have drug-resistant virus. The risk of developing drug resistance depends, in part, upon the type of regimen (eg, one that contains an agent with a high versus low barrier to resistance), as well as the level of adherence. (See 'Nonadherence' below and 'Poor absorption or altered metabolism' below and 'Resistance' below.)

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Literature review current through: Nov 2017. | This topic last updated: May 17, 2016.
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