Re-testing of blood samples from patients with suspected viral rebound above 50 copies/ml shows that in the majority of cases, the `blip` is a result of the variability of the assay, according to data presented at the Eighth Annual Conference of the British HIV Association.
Samples from 249 patients at London's Chelsea and Westminster Hospital with first viral load blips after suppression below 50 copies/ml were re-tested. 59% were found to give an undetectbale reading (below 50 copies) when re-tested. The remainder still had HIV -1 RNA levels above 50 copies/ml, and a repeated blip was predictive of subsequent virological failure (rebound above 400 copies/ml) (p<0.001). The Chiron Multiplex assay was used in this study.
The researchers suggested that in cases of viral blips, it may be more appropriate to re-test the blood sample rather than recalling the patient for another test.
References
Mazen Y et al. Evidence of low level viral replication (<50 copies/ml) predicts eventual virological failure. Eighth Annual Conference of the British HIV Association, York, abstract 011, 2002.