title: Predictive markers for hepatitis C antibody ELISA specificity in Australian blood donors.
abstract: The hepatitis C antibody reactivity rate in 91,748 blood donors tested using the ORTHO HCV C-100 ELISA system was 0.51%. Specificity of ELISA positive reactions was measured using a recombinant immunoblot assay (RIBA). The aim of this study was to identify markers in ELISA positive donors which were predictive of a RIBA positive result. Samples from 430 ELISA positive donors were tested by the first generation RIBA, RIBA-1, which incorporates two HCV peptides C-100 and 5-1-1. Fifty-five per cent (236) were positive and 19% (83) indeterminate. Multivariate analysis of gender, age, HCV ELISA OD ratio, alanine aminotransferase (ALT) status and hepatitis B core antibody (anti-HBc) status identified age, magnitude of HCV ELISA OD ratio and anti-HBc status as the only independent predictors of a positive RIBA-1 result. The relative odds of being RIBA-1 positive were 4.6-fold (95% CI 1.3-16.4) higher among donors aged 25-34 years compared with donors less than 25 or greater than 44; 6.1-fold (2.1-17.9) higher if the donor was anti-HBc positive and 273.4-fold (30.9-2417) higher if the HCV ELISA OD ratio was greater than 5.98 compared to those with a ratio less than 1.77. Seventy-eight of the 83 RIBA-1 indeterminates were tested on the second generation RIBA, RIBA-2, which includes two additional HCV peptide, C22 and C33c. Thirty-one per cent (24) were positive and 41% (32) were negative.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Australian Red Cross Blood Transfusion Service, Queensland Division, Brisbane.
authors.forename: C A
authors.initials: CA
authors.lastname: Hyland
authors.forename: S
authors.initials: S
authors.lastname: Kearns
authors.forename: I F
authors.initials: IF
authors.lastname: Young
authors.forename: D
authors.initials: D
authors.lastname: Battistutta
authors.forename: C L
authors.initials: CL
authors.lastname: Morgan
mesh_terms: D000328:Adult; D001315:Australia; D015415:Biomarkers / Q000097:blood; D001782:Blood Donors; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D016174:Hepacivirus / Q000276:immunology*; D006508:Hepatitis Antibodies / Q000097:blood*; D018937:Hepatitis C Antibodies; D006801:Humans; D015151:Immunoblotting; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
chemical_list: D015415:Biomarkers; D006508:Hepatitis Antibodies; D018937:Hepatitis C Antibodies