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Comparative Study
. 2004 Feb;57(2):141-5.
doi: 10.1136/jcp.2003.10835.

Clinical evaluation of the COBAS Amplicor HBV monitor test for measuring serum HBV DNA and comparison with the Quantiplex branched DNA signal amplification assay in Taiwan

C-Y Dai  1 , M-L Yu, S-C Chen, Z-Y Lin, M-Y Hsieh, L-Y Wang, J-F Tsai, W-L Chuang, W-Y Chang
Affiliations
Comparative Study

Clinical evaluation of the COBAS Amplicor HBV monitor test for measuring serum HBV DNA and comparison with the Quantiplex branched DNA signal amplification assay in Taiwan

C-Y Dai et al. J Clin Pathol. 2004 Feb.

Abstract

Aims: To evaluate the performance characteristics and clinical usefulness of the COBAS Amplicor HBV monitor (COBAS-AM) test in Taiwan and to examine its correlation with the Quantiplex branched DNA signal amplification (bDNA) assay for measuring serum hepatitis B virus (HBV) DNA concentrations.

Methods: HBV DNA was measured by the COBAS-AM test in 149 sera from chronic HBV infected patients that had previously been analysed by the bDNA assay.

Results: The COBAS-AM test showed good reproducibility, with acceptable intra-assay and interassay coefficients of variation (1.6% and 0.9%, respectively) and good linearity (r2=0.98). The overall sensitivity of the COBAS-AM test was significantly higher than that of the bDNA assay (95.3% v 83.2%): 69.6% of samples with HBV DNA below the detection limit of the bDNA assay could be measured by the COBAS-AM test. There was a significant correlation between the results of the two assays (r=0.901; p<0.0001). On average, the results derived from the COBAS-AM test were 0.55 log lower than those of the bDNA assay. HBV DNA concentrations were significantly higher among HBV e antigen (HBeAg) positive patients than negative ones, and higher among patients with abnormal alanine aminotransferase (ALT) concentrations than those with normal ALT concentrations (p=0.0003).

Conclusions: The COBAS-AM assay, more sensitive in HBeAg negative samples than the bDNA assay, can effectively measure HBV DNA concentrations in Taiwanese patients. HBV DNA values measured by the COBAS-AM test and bDNA assay correlate significantly.

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Figures

Figure 1
Figure 1
The linearity of hepatitis B virus (HBV) DNA measurement by the COBAS-AM test. Threefold serial dilution panels of sera from patients who were negative (sample 1) and positive (sample 2) for HBV e antigen (HBeAg) had 2.0 × 107 and 6.17 × 107 copies of HBV DNA/ml, respectively.
Figure 2
Figure 2
Comparison between hepatitis B virus (HBV) DNA values in samples from 124 patients with chronic HBV infection measured by the COBAS-AM test and the bDNA assay. There was a good correlation between all the specimens yielding values within the quantitative range of each of the assays (b  =  1.004; r  =  0.901). HBV values were expressed as log equivalents or log copies/ml. The lower detection limit of the bDNA assay is indicated by the broken line (0.7 × 106 equivalents/ml, which corresponds to 5.8451 log equivalents/ml).
Figure 3
Figure 3
Comparison between hepatitis B virus (HBV) DNA values in HBV e antigen (HBeAg) negative and positive samples from patients with chronic HBV infection measured by the COBAS-AM test. The HBV DNA value was significantly higher in HBeAg positive than in HBeAg negative patients (p < 0.0001). The mean serum HBV DNA values and SD values are shown in each group.
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