Comparison of the abbott 7000 and bayer 340 systems for measurement of hepatitis C virus load

Abstract

This study compared two commercially available assays for the measurement of hepatitis C virus (HCV) RNA levels, the Bayer HCV RNA (version 3.0) branched DNA assay and the Abbott HCV analyte-specific reagent real-time PCR assay, to assess their quantitative relationships, ease of performance, and time to completion. The study group consisted of randomly selected patients from the NIAID human immunodeficiency virus (HIV) outpatient clinic who were infected with HIV type 1 and HCV. One hundred eighty-four samples from 66 patients coinfected with HIV and HCV receiving treatments under various protocols were analyzed for the correlation and agreement of the results. The results indicated that the two assays correlate well in the overlapping linear ranges of the assays and show good agreement. From the results obtained, we have derived a mathematical formula to compare the viral load results between the two assays, which is given as log(10) Abbott assay measure = 0.032 + 1.01 log(10) Bayer assay measure. Although it is preferable to use the same quantitation assay throughout the course of a patient's treatment, valid comparisons of the HCV RNA levels may be made between the results obtained by either of these assays in the overlapping linear range (615 to 7,700,000 IU/ml).

FIG. 1.

Scatter plot of the Abbott assay readings versus the Bayer assay readings. Solid dots, samples in which RNA was detectable by both assays; triangles, samples with RNA undetectable by the Bayer assay (HCV was present at levels either below the lower detection limit or above the upper detection limit) but detectable by the Abbott assay. In addition, there were 41 samples with RNA undetectable by both assays (Bayer assay reading, <615 IU/ml; Abbott assay reading, <10 IU/ml). The four dashed lines specify the linear range for the Bayer assay, and the broken line is that of identity.

FIG. 2.

Plots of the differences between the viral load readings from the Bayer and Abbott assays versus the averages of the two assays. The line is from linear regression.