Methodology for RNA quantitation:
(1) branched DNA signal amplification (bDNA)
(2) reverse transcriptase PCR (RT-PCR)
(3) nucleic acid sequence based amplification (NASBA)
Suggested frequency of HIV RNA measurement (Saag, 1996):
(1) baseline: 2 measurements, 2-4 weeks apart
(2) every 3-4 months, or in conjunction with CD4+ counts
(3) shorter intervals as critical decision points are neared
(4) 3-4 weeks after initiating or changing therapy
Prognosis and Initiation of Therapy
The higher the number of HIV-1 RNA copies:
(1) the higher the percentage progressing to clinical AIDS
(2) the shorter the interval to development of clinical AIDS
(3) the higher the mortality rate
(4) the greater the transmission rate
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Number of copies per mL
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Interpretation
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< 1,000 copies
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very very low, with very low rate of progression
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1,000 - 5,000 copies
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very low levels
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5,000 - 10,000
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low to moderate levels
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10,000 - 30,000
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moderate levels
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30,000 - 50,000
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over half will develop clinical AIDs within 6 years of baseline visit
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50,000 - 100,000
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high levels
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> 100,000:
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very high levels, associated with rapid progression
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Plasma HIV RNA level that suggests initiation of treatment (Saag, 1996)
(1) more than 5,000- 10,000 copies per mL and a CD4+ count or clinical status suggestive of progression
(2) > 30,000 - 50,000 regardless of laboratory or clinical status
Monitoring during Therapy
Target level of HIV RNA after initiation of therapy: undetectable but < 5,000 copies per mL acceptable:
(1) minimal decrease in HIV RNA indicative of antiviral activity: a greater than 0.5 * log10 decrease
(2) a 10-fold decrease from baseline correlates with a significant reduction in risk for progression to AIDS or death
Drug Resistance
A change in HIV RNA that suggests drug treatment failure: return to, or within 0.3 to 0.5 * log10 of, pretreatment value (Saag, 1996)
