Surveillance and Screening of Blood Borne Pathogens

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Surveillance and Screening of Blood Borne
Pathogens

• Analysis of performance of HIV RNA, HCV, RNA and
  HBV DNA assays
• Vivienne James

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UK NEQAS for Microbiology Proficiency Testing
Panels

• EQA allows a comparison of the reproducibility of
  both an individual manufacturers assay and
  different manufacturers assays when used in
  different laboratories

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Data Presentation and Analysis

• Presentation of results data
• Table of number, range and median results by kit
• Histograms of absolute values reported
• Analysis based upon
• Accuracy of qualitative result (HCV)
• Accuracy of quantitative result (HIV and HBV)
• Difference in concentration from the consensus
  median

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HCV results (three of ten specimens distributed)
from January 2002
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HIV results from January 2002 (all specimens)
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Statistical Analysis

• Two-way analysis of variance
• HIV Roche assay 0.24 log 0.21 to 0.27 higher
  than Bayer
• HCV Roche assay 0.18 log 0.09 to 0.27 higher
  than Bayer
• Specimen Standard Deviation
• HIV Bayer 0.9 Roche 1.04
• HCV Bayer 0.22 Roche 0.29
• Evidence of greater variability in the Roche
  results compared with Bayer HIV p0.001 HCV
  p0.02

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