Low-level HIV-1 viraemia in patients on HAART: risk factors and management in clinical practice.

OBJECTIVES Characterization of the conditions favouring HIV-1 low-level viraemia (LLV) during treatment is required to guide strategies for prevention and cure. METHODS The characteristics and treatments of 171 patients experiencing a confirmed LLV of 50-1000 copies/mL (PLLVs) were compared with those of 146 patients with persistently controlled viraemia. We analysed the risk factors for LLV, the parameters affecting the level of viraemia and the presence of resistance-associated mutations (RAMs). We compared outcomes for PLLVs on fully effective HAART as a function of treatment modifications. RESULTS LLV was <500 copies/mL in at least 90% of cases. A higher zenith viral load (VL) (5.27 versus 4.91 log10 copies/mL, OR 2.23; P = 0.0003), a shorter time on continuous HAART (4.3 versus 6.8 years, OR 0.88; P = 0.0003) and previously detected RAMs (43% versus 23%, OR 2.42; P = 0.0033) were independent predictors of LLV. NNRTIs were less frequently used in PLLVs and were associated with more stable treatment. The presence of any RAM during LLV was associated with a lower zenith VL and a higher LLV. In the absence of resistance, virological success was achieved in similar proportions of patients with and without treatment modification. CONCLUSIONS Viraemia >500 copies/mL should no longer be considered to be LLV. In patients with a high zenith VL, several years on continuous HAART may be required to decrease the HIV reservoir and prevent LLV. Resistance testing is useful to detect RAMs, leading if necessary to treatment modifications. In the absence of resistance, treatment changes seemed dispensable.