Comparison of two diagnostic algorithms for the identification of patients with HCV viremia using a new HCV antigen test.

BACKGROUND Patients exposed to hepatitis C virus (HCV) may develop chronic infection with viremia. The diagnosis of this condition requires the use of several laboratory tests in algorithms tailored to the population and resources available for each laboratory. AIM We compared the diagnostic efficacy of two diagnostic algorithms for the identification of viremic patients with HCV. One based on confirmation of reactive antibody results with molecular techniques (reverse transcription polymerase chain reaction, RTPCR) and the other based on the use of a new HCV core antigen test (HCV Ag). Material and methods. We measured levels of anti-HCV, HCV Ag and viral load (trough RT-PCR) in parallel, in 211 samples (53 antibody positive, 158 antibody negative). Using the three results available for each sample we simulated the diagnostic performance of the two algorithms and compared them to the results of RT-PCR as gold standard. RESULTS Both algorithms showed a high degree of concordance for viremic patients. The percentage of correctly classified patients was 99.05% for the algorithm based on RT-PCR and 98.10% for the HCV Ag algorithm. The HCV core Ag test showed a clinical sensitivity of 0.917 and showed a good correlation to the results of molecular biology. Spearman rank correlation coefficient (ρ) of 0.97 (95% CI 0.95 to 0.99, p < 0.0001). CONCLUSION An algorithm incorporating HCV Ag as confirmatory test for anti-HCV results is a feasible alternative to the use of molecular techniques in laboratories that do not have access to them or require faster turn around times.