Clinical

Single HCV RNA assay not enough to guide treatment

Last Updated: 2006-02-15 16:32:35 -0400 (Reuters Health)

NEW YORK (Reuters Health) - Discrepancies occur when patients are monitored with different tests to detect and quantify hepatitis C virus (HCV) RNA, even when international units (IU) are used, French researchers report.

The findings confirm that relying on a single test of viral load to guide treatment is insufficient, and also suggest it may be important to use one type of assay when monitoring an HCV patient, Dr. Philippe Halfon of Alphabio Laboratory in Marseille and colleagues conclude in the February issue of the Journal of Medical Virology.

While some guidelines recommend discontinuing HCV treatment if RNA levels do not drop 2 log units by 12 weeks of therapy, Dr. Halfon and his team note, a previous study found that assays can give false-positive and false-negative results and can vary by more than 1 to 2 log IU.

The researchers followed 27 treatment-na�ve patients given ribavirin plus PEG-interferon-alfa-2b for 48 weeks using four assays: Bayer's Versant HCV RNA 3.0; Roche's TaqMan, a real-time PCR test; Abbott's LCx HCV RNA and Roche's Cobas Amplicor-Monitor v2.

Differences among the tests were seen at weeks 4 and 12 of treatment, the researchers found. Among 486 samples tested, 40% showed between-assay differences of 1 to 2 log units, while 2% showed a greater than 2 log unit difference and the rest, 58%, were within 1 log unit. Using the four different assays to predict a sustained viral response or non-response produced discordant results, the researchers found.

This study confirms that it is unwise to base treatment decisions on a single HCV RNA measurement, Dr. Halfon and colleagues conclude. "HCV-infected patients might be monitored with only one assay method."

J Med Virol 2006;78:208-215.