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Cutoff Value of Qualitative HBsAg for Confirmatory HBsAg Using the Chemiluminescence Microparticle Immunoassay Method
Merci Monica Pasaribu1, Jessica Purwanti Wonohutomo1, Suzanna Immanuel1
1Department of Clinical Pathology, Faculty of Medicine University of Indonesia/ National General Hospital Dr Cipto Mangunkusumo, Jakarta, Indonesia.
Background:
Confirmatory hepatitis B surface antigen (HBsAg) is an assay used to distinguish weakly reactive from false-positive HBsAg results.
Objective:
To determine the signal to cutoff (S/CO) value of chemiluminescence microparticle immunoassay (CMIA) HBsAg assay that should trigger follow-up confirmatory HBsAg testing.
Methods:
All specimens with an initial S/CO value of 0.90-100.00 were subjected to repeat HBsAg testing after high-speed centrifugation. The specimens with an initial S/CO value in that range remained in the same range and were then followed up with confirmatory HBsAg testing.
Result:
In total, 132 specimens had an S/CO value between 0.90 and 100.00 after high-speed centrifugation, followed by confirmatory HBsAg retesting. The S/CO value of HBsAg specimens for which the results required verification with confirmatory HBsAg was 0.98 (100% sensitivity, 3.3% specificity) through 9.32 (47.1% sensitivity, 100% specificity).
Conclusion:
The HBsAg S/CO values (as determined by the chemiluminescent microparticle immunoassay [CMIA] method) that should trigger confirmatory HBsAg testing are 0.98-9.32.
