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Changes in viral load in people with virological failure who remain on the same HAART regimen
Alessandro Cozzi-Lepri1, Andrew N Phillips, Veronica Miller
1Royal Free Centre for HIV Medicine & Department of Primary Care and Population Sciences, Royal Free and University College Medical School, Royal Free Campus, London, UK.
Objectives:
To assess the rate of change in viral load and CD4 count over time in HIV-infected patients experiencing virological failure on a HAART regimen.
Design:
Study population included patients from EuroSIDA, a large, multicentre, observational study enrolling HIV-infected patients across Europe.
Methods:
Median change in viral load and CD4 count per month were estimated using the viral load and CD4 measurements obtained over a 12-month period after confirmed virological failure between 3 and 4 log10 copies/ml in a population of 488 HIV-infected patients who were left on a failing HAART regimen.
Results:
The estimated median viral load change in our study population was 0.024 log10 copies/ml per month, statistically different from 0 (P=0.0001). In 20.9% of the patients studied viral load showed a tendency to decrease, in 47.8% showed a tendency to increase by a positive rate no higher than 0.04 log10 copies/ml per month and in the remaining 31.3% showed a tendency to increase by a rate greater than 0.04 log10 copies/ml per month. On average, CD4 counts were estimated to remain stable (decrease at a slow rate of about -0.53 cells/microl per month).
Conclusions:
In patients that remained on a stable, but virologically failing HAART regimen (with viral load ranging 1000-10000 copies/ml), the viral load over the ensuing 12-month period increased at a relatively slow rate. In contrast, the CD4 count remained stable, possibly because of partial but sustained viral suppression below the viral load natural set-point. The time-course of selecting more replication-competent virus in patients with virological failure remains to be fully clarified.