Hepatitis C Immunoassays Evaluated

The performance characteristics of three premarket anti-HCV immunoassays have been evaluated and compared for their sensitivity and specificity.

Scientists at the US Centers of Disease Control (CDC; Atlanta, GA, USA) examined six different studies that used lateral flow immuno-chromatographic assay devices for testing serum, finger stick blood, and oral fluid from three manufacturers. Active HCV infection was determined by quantitative nucleic acid testing (NAT) which detects the presence of HCV ribonucleic acid (RNA).

The three immunoassays used in the studies were from Chembio (Medford, NY, USA); MedMira (Halifax, NS, Canada); and Orasure (Bethlehem, PA, USA). Overall sensitivity and specificity was highest when serum specimens were compared to finger stick and oral fluid samples. The sensitivity of the Orasure test was higher that of the Chembio or MedMira assays.

False negative and false positive results occurred with all assays and specimens. Orasure had the least number of false negative at 0% to 6%, while the MedMira assay yielded the largest proportion of false negatives. In two studies, false negatives were associated with human immunodeficiency viral infections. In one study, the Orasure assay outperformed the conventional enzyme immunoassay (EIA).

The authors concluded that anti-HCV tests detect both current and past infection, but cannot differentiate between them. Patients who are positive with a rapid anti-HCV test should also be tested with NAT, which is more expensive and labor intensive. The authors note that a quantitative antigen assay Architect HCV Ag (Abbott, Abbott Park, IL, USA) which is performed on an automated platform is available in Europe. This assay is also less expensive and does not require the intensive labor of the NAT, but is less sensitive. The study was published on December 7, 2012, in the journal Antiviral Therapy.

Related Links:
US Centers of Disease Control
Orasure
Abbott