HIV Digest	HIV Digest Archive

The intermittent detection of viral load in patients who normally have undetectable viral loads (<50 copies/mL) has been referred to as "viral load blipping." There has been considerable concern among both patients and providers that these blips are early warning signs of treatment failure and could be an early demonstration of the development of drug resistance.

Researchers in a recent study frequently monitored the viral load of a small group of patients to determine the clinical significance of viral load blipping.

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Viral load and resistance testing were performed on blood samples from 10 patients. The blood samples were obtained every Monday, Wednesday and Friday for three months. Patients were also questioned about any significant clinical events at every visit.

Ninety percent of the patients experienced viral load blips, with an average of 0.6 blips per month, a median increase in viral load of 79 copies/mL. The median duration of the blip was 60 hours. The total number of blips detected during the study was 26/723 (3.6%), or an average of two blips every three months per person.

The detection of blips correlated poorly between testing laboratories. Nine blips were detected by one lab and 8 blips by another lab. Only one blip was detected by both labs.

The presence of blips did not correlate with either patient variables (age, race or gender) or clinical variables (CD4 nadir, CD4 at study baseline, time of HIV infection, number of antiretroviral medications, number of prior blips, influenza vaccination or acute infections, such as sore throats or herpes outbreaks).

Nine out of 10 patients' virus was successfully sequenced; no new significant reverse transcriptase mutations, and only one protease gene mutation, were detected when viral load blipping was noted.

The authors conclude from their small study that almost all patients have some degree of blipping and that most blips were the result of assay variation-- in other words, the blips did not indicate treatment failure or the development of resistance. This is suggested by the fact that no new resistance mutations were found during blipping, that no patient's viral load had a sustained increase and that two independent laboratories doing the viral load testing had very poor correlation when blips were found.

This short-term study confirms longer-term observations (which had less-frequent viral load measurements) that blipping does not predict or predate virologic failure. This study is important in that practitioners can be somewhat more assured that they need not change antiretroviral regimens at the first sign of a low, but detectable, viral load.

Editor's Note: from TheBodyPro.com