title: Threshold value of LIAISON XL anti-HCV screening assay predicting positive immunoblotting results.
abstract: Some international guidelines recommend evaluating the need to confirm positive anti-hepatitis C virus (HCV) antibody screening results by means of a more specific antibody or molecular biology test on the basis of a screening threshold value (such as the sample signal/cut-off ratio) that can predict the positivity of additional antibody testing in at least 95% of cases. The aim of this study was to determine the threshold value of the DiaSorin LIAISON XL chemiluminescence test. Two hundred and twenty-eight routine laboratory samples that were chemiluminescence positive for anti-HCV antibodies but had different signal/cut-off ratios were assayed using immunoblotting, which indicated that 155 (68.0%) were positive, 40 (17.5%) were negative, and 33 (14.5%) were indeterminate. When the samples were divided on the basis of their signal/cut-off ratios, 95.5% of the samples with a ratio of ≥3.5 were positive as against 74.1% of the positive or indeterminate samples with a ratio of <3.5. Statistical analysis using Youden's index and a receiver operating characteristic curve showed that the optimum cut-off value was 3.65. These findings indicate that, when using the LIAISON XL system for anti-HCV antibody screening, a signal/cut-off ratio of ≥3.65 makes further confirmatory tests unnecessary.
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Massimo
authors.identifier: 0000-0002-4770-6399
authors.initials: M
authors.lastname: De Paschale
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Manco
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Olivia
authors.initials: O
authors.lastname: Arpino
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Ricucci
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Alessia
authors.initials: A
authors.lastname: Paganini
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Belvisi
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Debora
authors.initials: D
authors.lastname: Cagnin
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Teresa
authors.initials: T
authors.lastname: Cerulli
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Annalisa
authors.initials: A
authors.lastname: Cianflone
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Agrappi
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Paola
authors.initials: P
authors.lastname: Mirri
authors.affiliation: Microbiology Unit, ASST Ovest Milanese, Hospital of Legnano, Legnano, Milan, Italy.
authors.forename: Pierangelo
authors.initials: P
authors.lastname: Clerici
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001782:Blood Donors; D002648:Child; D005260:Female; D016174:Hepacivirus / Q000276:immunology; D006526:Hepatitis C / Q000175:diagnosis* / Q000453:epidemiology / Q000276:immunology; D018937:Hepatitis C Antibodies / Q000097:blood*; D006801:Humans; D007118:Immunoassay; D015151:Immunoblotting; D007558:Italy; D008163:Luminescent Measurements / Q000379:methods*; D008297:Male; D008875:Middle Aged; D012372:ROC Curve; D012189:Retrospective Studies; D055815:Young Adult
chemical_list: D018937:Hepatitis C Antibodies
keywords: hepatitis C virus; immunological techniques; inapparent infection