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Laboratory evaluation of UniCel DxI 800 analyser (Beckman Coulter) for HBV and HCV serological markers

Abstract number: P949

Miedouge M., Abravanel F., Lalanne C., Izopet J.

Objectives: The UniCel DxI 800 analyser (Beckman Coulter) is a multiparametric immunoassay system with random access that uses magnetic particules separation and indirect chemiluminescent technology.

In this study, intra-assay and inter-assay precision, and a comparison with the Vitros ECi (Ortho Clinical diagnosis) were evaluated for the following virological markers: antibody to hepatitis C virus (anti-HCV) and four hepatitis B virus (HBV) markers i.e. HBsAg, anti-HBc, anti-HBc IgM and anti-HBs.

Methods: Intra-assay precision was determinated by measuring within one run 20 replicates of the manufacturer positive controls. For inter-assay precision, the same controls were tested daily during the evaluation period in 26 to 36 runs depending on the markers.

Comparison of the two analysers was assessed by testing patients sera previously analysed in our laboratory with the Vitros ECi and stored at -23±5°C. Negative and positive samples were compared: respectively 104 and 108 for HBsAg, 120 and 133 for anti-HBs, 225 and 36 for anti-HBc, 103 and 21 for anti-HBc IgM and 109 and 26 for anti-HCV

For the quantitative anti-HBs assay, correlation with the Vitros was determined with the Spearman regression test. Moreover linearity, accuracy and detection limit were evaluated using serial dilutions (from 500 mUI/ml to 10 mUI/ml) of the WHO internationnal standard for anti-HBs (W1042).

Results: Coefficient of variation for intra-assay and inter-assay tests were respectively 0.8% and 4.4% for HBsAg, 2.1% and 5.1% for anti-HBs, 2.4% and 6.2% for anti-HBc, 5% and 8.7% for anti-HBc IgM and 3.7% and 7.4% for anti-HCV.

The concordance rates between the two methods were high: 100% for the five markers except for negative HBsAg sera where one discordant result was observed (99% concordance). Anti-Hbs results appeared statistically correlated either with Vitros results or with the WHO standard (p<0.01 with Spearman test). All the five replicates of the 10 mUI/ml sample were detected. The throughput of the analyser was estimated at about 200 tests per hour.

Conclusion: The results of this evaluation confirmed that the five assays meet the criteria of the Common Technical Specifications of the European Union's Directive on In Vitro Diagnostic Medical Devices in terms of specificty and sensitivity. Together with a high throughput, the DXI provides a useful tool for serological diagnosis of HCV anc HBV infection in routine practice.

Session Details

Date: 19/04/2008
Time: 00:00-00:00
Session name: 18th European Congress of Clinical Microbiology and Infectious Diseases
Subject:
Location: Barcelona, Spain
Presentation type:
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