Viral load over 5,000 on treatment increases AIDS risk

People on anti-retroviral treatment who fail to maintain viral load below 5,000 copies are almost two and a half times more likely to become ill or die within 12 months than people who maintain viral load below 500 copies. Maintaining a viral load below 5,000 copies - but above 500 copies - didn't substantially increase the risk of becoming ill.

Every one log reduction in viral load after one month of treatment was associated with a 50% reduction in the risk of illness, according to researchers from the INSERM research centre in Bordeaux.

On the other hand, a viral load reduction of less than 0.5 log regardless of baseline viral load by week four was strongly associated with a poor long-term response.

The authors say their findings should be taken into account in cases of viral rebound, especially where people have received many of the available anti-retrovirals.

"A sustained HIV RNA level between 2.7 log and 3.7 log may permit the deferral of a change of drug regimen according to the patient's history and therapeutic options" the authors conclude, reporting in the journal AIDS.

A total of 773 French patients were reviewed, of whom 47% were receiving triple therapy. Thirty-nine per cent of the cohort were treatment-naïve, but the rest had taken at least one dual nucleoside analogue combination before the follow-up period began in mid-1996. Prior treatment experience did not significantly increase the risk of a poor response or subsequent illness.

Baseline viral load was around 25,000 to 40,000 copies/mL, and 45% of patients achieved viral load below 500 copies, with 26% falling below 5,000 but not reaching 500 copies, and 29% failing to achieve viral load below 5,000 copies.

Several other studies have reported similar results (see Monitoring treatment with viral load), but this is the first review of people who received protease inhibitor treatment.