Ann Lab Med.  2012 Nov;32(6):420-425.

Elecsys Hepatitis B Surface Antigen Quantitative Assay: Performance Evaluation and Correlation with Hepatitis B Virus DNA during 96 Weeks of Follow-up in Chronic Hepatitis B Patients

• Lee HJ
• Kim SY
• Lee SM
• Heo J
• Kim HH
• Chang CL
• Lee EY
• Son HC

Abstract

BACKGROUND
Treatment for chronic hepatitis B aims to suppress virus replication and virus sequestration in hepatocytes. Covalently closed circular (ccc) DNA is the template for transcription of viral genes and is responsible for viral persistence. However, limited data are available for quantification of hepatitis B surface antigen (HBsAg) in Korea.
METHODS
We evaluated the Elecsys HBsAg II quant assay (Roche Diagnostics, USA) for within-run, between-run, and between-day precisions, linearity, carryover, and clinical specificity. In total, 156 serum samples were evaluated for correlation between HBsAg and hepatitis B virus (HBV) DNA. Serial samples were obtained from 10 patients at 0, 12, 24, 48, 72, and 96 weeks during follow-up.
RESULTS
The assay detected HBsAg in a linear range of 0.5-48,696 IU/mL. Within-run, between-run, and between-day CVs were 2.9-4.1%, 0-1.5%, and 1.5-4.9%, respectively. Cross-reactivity between potentially interfering substances was absent, and the carryover rate was 0.00002%. The correlation of measurements between the Elecsys assay and HBV DNA PCR was weak (r=0.438, P=0.002). For predicting virologic response, cutoff values of 10,275 IU/mL and 3,846 IU/mL at 12 and 24 weeks after treatment initiation showed positive predictive values of 77.1% and 85% and negative predictive values of 84.6% and 50%, respectively.
CONCLUSIONS
The Elecsys HBsAg II quant assay showed good performance for precision, linearity, carryover rate, and specificity. HBsAg level at baseline, 12 weeks, and 24 weeks after treatment initiation can predict virologic response, and the assay can be used for HBsAg quantification in clinical practice.

Keyword

HBsAg; Quantification; Hepatitis B virus; Chronic hepatitis B

MeSH Terms

Analysis of Variance
Antiviral Agents/therapeutic use
DNA, Viral/analysis
Follow-Up Studies
Hepatitis B Surface Antigens/*blood
Hepatitis B virus/genetics/*metabolism
Hepatitis B, Chronic/drug therapy/*virology
Humans
Polymerase Chain Reaction
ROC Curve
Reagent Kits, Diagnostic
Time Factors
Antiviral Agents
DNA, Viral
Hepatitis B Surface Antigens
Reagent Kits, Diagnostic

Figure

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  Fig. 1 Linearity range of the Elecsys HBsAg II quant assay. Abbreviation: HBsAg, hepatitis B surface antigen.

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  Fig. 2 Correlation between HBsAg measurements using the Elecsys HBsAg II quant assay and the level of HBV DNA in the first follow-up samples from 46 patients. Abbreviations: HBV, hepatitis B virus; HBsAg, hepatitis B surface antigen.

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  Fig. 3 Serial concentration curves of HBsAg levels and HBV DNA levels in 10 follow-up patients. Abbreviations: HBsAg, hepatitis B surface antigen; HBV, hepatitis B virus.

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  Fig. 4 HBsAg level at pretreatment and 12 weeks, 24 weeks after treatment initiation according to achieving a sustained virologic response. Abbreviations: HBsAg, hepatitis B surface antigen; NR0, non-responder at baseline; R0, responder at baseline; NR12, non-responder at 12 weeks after treatment initiation; R12, responder at 12 weeks after treatment initiation; NR24, non-responder at 24 weeks after treatment initiation; R24, responder at 24 weeks after treatment initiation.

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  Fig. 5 ROC analysis to identify cutoff level of HBsAg to predict virologic response at baseline, 12 weeks, and 24 weeks after the start of the treatment. Abbreviation: HBsAg, hepatitis B surface antigen.

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