The significance of very low-level viraemia detected by sensitive viral load assays in HIV infected patients on HAART

Objectives: Viral load (VL) measurement is critical for monitoring the effectiveness of highly active antiretroviral therapy (HAART). HAART aims to maintain plasma HIV RNA at undetectable levels. A VL <50 copies/ml was previously considered undetectable. After introducing more sensitive assays many patients with VL <50 copies/ml were found to have very low-level viraemia (VLLV), defined as a detectable VL <40 copies/ml. This study aimed to determine the significance of VLLV. Methods: This retrospective case-control study included 69 individuals on HAART with VLLV. Immunological and virological outcomes over 36 months were compared to those of 70 well-matched controls with persistently undetectable VL. Results: We detected no significant association between VLLV and the development of virological failure or inferior immunological outcomes. However, individuals with VLLV were significantly less likely to achieve subsequent sustained virological suppression (VL <50 copies/ml, p < 0.001), including completely undetectable suppression (undetectable VL < 40 copies/ml, p = 0.002). Conclusions: The significance of VLLV has been uncertain. Our results clearly suggest that VLLV is predictive of future suboptimal virological control, particularly a reduced likelihood of achieving virological suppression. Further work should confirm our findings and evaluate strategies for managing VLLV in HAART-treated patients. (C) 2010 The British Infection Association. Published by Elsevier Ltd. All rights reserved.