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Learning Objectives for this Presentation:
By the end of the presentation, participants will be able to discuss the reliability and feasibility of using the HCV EIA signal to cutoff ratio (s/co) to predict HCV RIBA result.
Background:
In 2003, CDC provided guidelines for using the signal to cut-off ratio (s/co) to predict a true antibody-positive result for HCV testing.
Methods:
The Florida Public Health Laboratory performed 18,521 anti-HCV EIA tests between January 1, 2001, and May 31, 2003. The s/co was calculated and a RIBA was performed for each specimen that was repeatedly reactive (RR) with the anti-HCV EIA assay; these results were compared to determine if samples with s/co > = 3.8 (Abbot) or >= 8.0 (Ortho Vitros assay and ECi analyzer) were predictive of a positive RIBA.
Results:
Between January 1, 2001, and May 31, 2003, 18,521 specimens were tested, and of these, 2155 were anti-HCV EIA repeatedly reactive (RR). The s/co and RIBA results were available for 2,139 of the 2,155 RR anti-HCV EIA specimens; the supplemental test was positive for 96.9% of the samples with a s/co ratio > or = 3.8. Use of a s/co ratio of >3.8 to determine a true EIA positive would have resulted in 89% of specimens not needing a RIBA supplemental test. Since implementing this test algorithm in February 2004, over 80 % of the HCV antibody positive specimens have yielded a s/co > = 8.0. Supplemental HCV antibody testing is performed only on specimens yielding a s/co < 8.0.
Conclusions:
The s/co of anti-HCV screening test positive results can be used minimize the number of specimens that require supplemental testing while providing results that have high probability of reflecting the person's true antibody status. The use of the s/co between February 2004 and September 2004 saved over $61,000 in supplemental HCV testing costs and $ 3,723 in technologist time.
Web Page: www.doh.state.fl.us/disease_ctrl/aids/hep/index.html
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