Viral load assay sensitivity and low level viremia in HAART treated HIV patients

Influence of Episodes of Intermittent Viremia (“Blips”) on Immune Responses and Viral Load Rebound in Successfully Treated HIV-Infected Patients

“…Some studies have demonstrated that repeated analysis of the same sample can show variations to 40%, 24,[39][40][41] in particular when VL is low or depending on the assay used. 42,43 On the other hand, some patients presented several low level EIV, which is contrary to a random variation. 44 Thus, another possible explanation is that patients who present with very low-level EIV are the ones who will really benefit from a controlled virus exposition, large enough to increase specific responses, but small enough to avoid the deleterious effects of activation and increase of replication.…”

High correlation between the Roche COBAS® AmpliPrep/COBAS® TaqMan® HIV-1, v2.0 and the Abbott m2000 RealTime HIV-1 assays for quantification of viral load in HIV-1 B and non-B subtypes

“…Thus, at low level VL the HIM v1.5 test returns titers lower than the two real-time assays and more results below the lower quantitation limit with more substantial discrepancies, a finding consistent with reported results for the HIM v1.5 test. [30][31][32] Although the DHHS guidelines recently changed the definition of virologic failure as a confirmed viral load >200 cp/mL to eliminate most cases of apparent viremia caused by blips or assay variability, the threshold of below 50 cp/mL remains the current standard in clinical practice and both real-time assays showed good agreement at this cut-off. Benefits of maximal viral suppression on treatment outcomes, immune activation, drug resistance and progression to AIDS support the tendency to lower the standard to 20 cp/mL.…”

“…Preliminary studies suggest that HIV RNA levels between 20 and 50 cp/mL indicate true viremia or are predictive of future suboptimal virological control and should be considered when assessing the outcome of ART. 19,32,34 Although several studies have shown that transient blips do not result in increased risk of virologic or clinical failure, there is evidence that persistently detectable viremia under HAART predicts subsequent virologic failure, development of drug resistance mutations and lower CD4 increases on ART. 35,36 The need to quantify accurately low level viral load is therefore still required.…”

Lopinavir Plasma Concentrations and Virological Outcome with Lopinavir-Ritonavir Monotherapy in HIV-1-Infected Patients

“…The main objective was to correlate plasma LPV levels with virological efficacy at 48 and 96 weeks, with VF defined as either (i) two consecutive viral load measurements of Ͼ200 copies/ml, (ii) a unique HIV RNA measurement of Ͼ200 copies/ml if followed by a loss of follow-up, or (iii) the reintroduction of nucleos-(t)ide analogues for any reason. A cutoff level of 200 copies/ml was chosen because it is a more accurate measurement of VF than a lower cutoff value (22,23). Because this was a pharmacological study, the main efficacy analysis was performed on the per-protocol population in which missing data or changes caused by toxicity were censored.…”