Page 95 - HIV/AIDS Guidelines

Virologic rebound: Confirmed detectable HIV RNA (to >200 copies/mL) after virologic suppression.

Persistent low-level viremia: Confirmed detectable HIV RNA levels that are <1,000 copies/mL.

Virologic blip: After virologic suppression, an isolated detectable HIV RNA level that is followed by a
return to virologic suppression.
Causes of Virologic Failure

Virologic failure in a patient can occur for multiple reasons. Data from older patient cohorts suggested that
suboptimal adherence and drug intolerance/toxicity accounted for 28%–40% of virologic failure and regimen
discontinuations. 1-2 More recent data suggest that most virologic failure on first-line regimens occurred due
3
to either pre-existing (transmitted) drug resistance or suboptimal adherence. Factors associated with
virologic failure include:

• Patient characteristics
• higher pretreatment or baseline HIV RNA level (depending on the specific regimen used)
• lower pretreatment or nadir CD4 T-cell count

• prior AIDS diagnosis
• comorbidities (e.g., active substance abuse, depression)
• presence of drug-resistant virus, either transmitted or acquired
• prior treatment failure
• incomplete medication adherence and missed clinic appointments

• ARV regimen characteristics
• drug side effects and toxicities
• suboptimal pharmacokinetics (variable absorption, metabolism, or, theoretically, penetration into
reservoirs)
• food/fasting requirements
• adverse drug-drug interactions with concomitant medications
• suboptimal virologic potency

• prescription errors
• Provider characteristics, such as experience in treating HIV disease
• Other or unknown reasons

Management of Patients with Virologic Failure
Assessment of Virologic Failure

If virologic failure is suspected or confirmed, a thorough work-up is indicated, addressing the following
factors:

• change in HIV RNA and CD4 T-cell counts over time
• occurrence of HIV-related clinical events
• ARV treatment history
• results of prior resistance testing (if any)

• medication-taking behavior (including adherence to recommended drug doses, dosing frequency,
and food/fasting requirements)

Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents H-2

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