SAN FRANCISCO — Progression to virologic failure occurred in a minority of HIV patients up to a year after having low-level viremia, and in no patients with very low-level viremia, according to data presented at the 52nd Interscience Conference on Antimicrobial Agents and Chemotherapy.
Although most patients who made a change in combination antiretroviral therapy in the study achieved undetectable viral levels, change did not affect the rate of virologic failure.
"In the case of persistent low-level viremia, cART intensification did not affect the rate of virological failure, but did significantly increase the rate of undetectability," study researcher Noémie Boillat Blanco, MD, told Infectious Disease News.
Blanco, of the University of Lausanne in Switzerland, and colleagues performed a case-control study from 2000 to 2008, comparing 179 patients who presented with persistent low-level viremia (a viral load of 21 copies/mL to 400 copies/mL on three or more consecutive plasma samples) and did not change combination ART vs. 5,389 patients in a control group who presented with a viral load of 20 copies/mL or less and did not change therapy until after at least 32 weeks of treatment.
Patients with low-level viremia had worse adherence to combination ART (adjusted OR=1.9; 95% CI, 1-3.3) and were less often on non-nucleoside reverse transcriptase inhibitors (AOR=0.5; 95% CI, 0.3-0.8). More patients had low-level viremia after 2008 (AOR=6.4; 95% CI, 3.5-11.4), and most patients (66%) still had low-level viremia at 48 weeks, and 12% presented with virologic failure.
A predictor of virologic failure was suboptimal adherence (AOR=3.7; 95% CI, 0.95-14.04). No patient with very low-level viremia (21 copies/mL to 49 copies/mL) experienced virologic failure. Forty-eight weeks after having low-level viremia, 28% of patients changed combination ART. Predictors of changing therapy included being on regimens consisting only of non-nucleoside reverse transcriptase inhibitors (AOR=9.6; 95% CI, 1.6-6.7), nadir CD4 count of 200 cells/mcL or less (AOR=5; 95% CI, 1.4-18.3) and low-level viremia onset after 2008 (AOR=3.8; 95% CI, 1.1-12.3).
Among patients who changed combination ART, 63% had undetectable viral levels by 24 weeks vs. 33% of those who did not change (P=.001). Virologic failure occurred in 9% of those who changed therapy and in 12% of those who did not (P=.8).
“Low-level viraemia may arise in patients with previously undetectable HIV viral loads on [combination] ART,” the researchers wrote. “It is important to know the implications of [low-level viraemia] and the benefit of [combination] ART.”
For more information:
Boillat Blanco N. Presented at: 52nd ICAAC; Sept. 9-12, 2012; San Francisco.