Page 30 - HIV/AIDS Guidelines

Table 4. Recommendations for Using Drug-Resistance Assays
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Clinical Setting/Recommendation Rationale

Drug-resistance assay recommended
In acute HIV infection: Drug-resistance testing is recommended If ART is to be initiated immediately, drug-resistance testing will
regardless of whether ART is initiated immediately or deferred determine whether drug-resistant virus was transmitted. Test
(AIII). A genotypic assay is generally preferred (AIII). results will help in the design of initial regimens or to modify or
change regimens if results are obtained subsequent to treatment
initiation.
Genotypic testing is preferable to phenotypic testing because of
lower cost, faster turnaround time, and greater sensitivity for
detecting mixtures of wild-type and resistant virus.
If ART is deferred, repeat resistance testing should be If ART is deferred, testing should still be performed because of
considered at the time therapy is initiated (CIII). A genotypic the greater likelihood that transmitted resistance-associated
assay is generally preferred (AIII). mutations will be detected earlier in the course of HIV infection.
Results of resistance testing may be important when treatment is
initiated. Repeat testing at the time ART is initiated should be
considered because the patient may have acquired a drug-
resistant virus (i.e., superinfection).
In ART-naive patients with chronic HIV infection: Drug- Transmitted HIV with baseline resistance to at least one drug is
resistance testing is recommended at the time of entry into HIV seen in 6%–16% of patients, and suboptimal virologic responses
care, regardless of whether therapy is initiated immediately or may be seen in patients with baseline resistant mutations. Some
deferred (AIII). A genotypic assay is generally preferred (AIII). drug-resistance mutations can remain detectable for years in
untreated chronically infected patients.

If therapy is deferred, repeat resistance testing should be Repeat testing prior to initiation of ART should be considered
considered prior to the initiation of ART (CIII). A genotypic assay because the patient may have acquired a drug-resistant virus
is generally preferred (AIII). (i.e., a superinfection).
Genotypic testing is preferable to phenotypic testing because of
lower cost, faster turnaround time, and greater sensitivity for
detecting mixtures of wild-type and resistant virus.
If an INSTI is considered for an ART-naive patient and Standard genotypic drug-resistance assays test only for
transmitted INSTI resistance is a concern, providers may wish to mutations in the RT and PR genes.
supplement standard resistance testing with a specific INSTI
genotypic resistance assay (CIII).

In patients with virologic failure: Drug-resistance testing is Testing can help determine the role of resistance in drug failure
recommended in persons on combination ART with HIV RNA and maximize the clinician’s ability to select active drugs for the
levels >1,000 copies/mL (AI). In persons with HIV RNA levels new regimen. Drug-resistance testing should be performed while
>500 but <1,000 copies/mL, testing may be unsuccessful but the patient is taking prescribed ARV drugs or, if not possible,
should still be considered (BII). within 4 weeks after discontinuing therapy.

A standard genotypic resistance assay is generally preferred for Genotypic testing is preferable to phenotypic testing because of
those experiencing virologic failure on their first or second lower cost, faster turnaround time, and greater sensitivity for
regimens (AIII). detecting mixtures of wild-type and resistant virus.

In patients failing INSTI-based regimens, genotypic testing for Standard genotypic drug-resistance assays test only for
INSTI resistance should be considered to determine whether to mutations in the RT and PR genes.
include drugs from this class in subsequent regimens (BIII).

Guidelines for the Use of Antiretroviral Agents in HIV-1-Infected Adults and Adolescents C-12

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