Background: Viremia copy-years (VCY) is associated with mortality and disease outcome prediction. This study evaluated the association of VCY with virological failure (VF), defined as a plasma viral load (pVL) >400 copies/mL, and with single levels of viremia.
Methods: Eight hundred and fifty antiretroviral therapy (ART)-treated patients with pVL < 37 copies/mL [target not detected or target detected (TD)] or >37, but less than 200 copies/mL (low-level viremia), and at least 6-pVL measures during 54 months of follow-up were selected. VCY was calculated individually over the follow-up as the area under pVL curve. Pearson's χ test was used to analyze differences in VCY quartiles distribution between groups.
Results: Higher VCY values were detected in patients with low-level viremia {294 copy-years [interquartile range (IQR): 99-1870]} than in TD [52 copy-years (IQR: 53-153)] and target not detected groups [19 copy-years (IQR: 8-54)]. VCY was also significantly different between patients with undetectable viremia and patients with basal pVL TD (P < 0.001). Pearson's χ test revealed a significant association between VCY and basal levels of viremia (P < 0.0001). In addition, the risk of VF rose with increasing VCY (Hazard ratio 1.01, 95% confidence interval: 1.01 to 1.02).
Conclusions: This study revealed the association of VCY with VF and with single levels of viremia suggesting that, despite the success of ART, minimal residual viremia may cause the cumulative viral burden to rise. Full viral load suppression during ART is crucial to limit the increase in VCY.