Viral Load: New Recommendations for Clinical Practice

A panel of leading HIV clinicians and researchers has published interim recommendations for how to use viral load testing, based on currently available knowledge.(1) The recommendations, which appear in the June 1996 issue of NATURE MEDICINE, answer common questions of physicians and patients about when to use the test and what the numbers mean. The information is current; while the recommendations represent months of work by the authors, NATURE MEDICINE published them very rapidly, about one month after receiving the manuscript.

The article summarizes the recommendations in a table:

"* Plasma HIV RNA level that suggests initiation of treatment: More than 5,000-10,000 copies/ml and a CD4+ count/clinical status suggestive of progression; [or] >30,000-50,000 regardless of laboratory/clinical status.

* Target level of HIV RNA after initiation of treatment: Undetectable; <5,000 copies/ml is an acceptable target.

* Minimal decrease in HIV RNA indicative of antiviral activity: >0.5 log decrease.

* Change in HIV RNA that suggests drug treatment failure: Return to (or within 0.3 to 0.5 log of) pretreatment value.

* Suggested frequency of HIV RNA measurements: At baseline, 2 measurements, 2-4 weeks apart. Every 3 to 4 months or in conjunction with CD4+ counts. Shorter intervals as critical decision points are neared. 3-4 weeks after initiating/changing therapy."

(For those not familiar with logarithms, a 1.0 log change means a 10-fold change; a 0.5 log change is about 3-fold; and a 0.3-log change is 2-fold. So the third of the five points quoted above means that an antiviral treatment should decrease viral load to less than a third of its starting value, for the physician to be confident that the treatment is working. Less of a decrease might have been due to testing errors, or to normal daily fluctuations in viral load.)

The NATURE MEDICINE paper also reviewed the major published research on the relationship of viral load to HIV disease progression.

The team which prepared the recommendations was convened by the International AIDS Society U.S.A.

References

1. Saag MS, Holodniy M, Kuritzkes DR, O'Brien WA, Coombs R, Poscher ME, Jacobsen DM, Shaw GM, Richman DD, and Volberding PA. HIV viral load markers in clinical practice. NATURE MEDICINE; June 1996. Volume 2, number 6, pages 625-629.