How is virologic failure of antiretroviral therapy for HIV infection defined by the DHHS guidelines?

Updated: Apr 18, 2019
  • Author: R Chris Rathbun, PharmD, BCPS (AQ-ID), AAHIVP; Chief Editor: John Bartlett, MD  more...
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Virologic failure, as defined in the DHHS ART Guidelines, is the failure to suppress and/or sustain a viral load < 200 copies/mL. [8] Although some controversy remains, a viral load of >200 copies/mL is used to define virologic failure based on data that supports ongoing viral evolution and resistance development at these levels.

There are conflicting data regarding patients with low-level viremia (viral loads between the lower limit of detection and 200 copies/mL). The risk of resistance developing at these lower viral loads is thought to be minimal; therefore, current guidelines recommend that these patients continue current therapy and be monitored every 3 months to assess the need for alteration.

In contrast, patients with persistent viral loads ≥200 copies/mL should be tested for resistance.  The ability of assays to detect resistance is greater with increasing viral load and may be difficult with viral loads between 200 and 500 copies/mL.  Below 500 copies/mL, changing antiretroviral therapy empirically should be done only on a case by case basis.

Table 3. Contributing Factors to Development of Virologic Failure [8] (Open Table in a new window)



Antiretroviral Regimen-Related

Comorbidities contributing to adherence

Presence of drug-resistance mutations (transmitted or acquired)

Pharmacokinetic properties

Social and psychosocial aspects

History of treatment failure

Virologic potency

Appointment attendance

Innate viral resistance (tropism/HIV-2)

Barrier to resistance

Consistent access to ART

HIV RNA level

Previous antiretroviral exposure


Administration requirements

Regimen burden

Drug-drug interactions

Prescription errors

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