Sensitivity of hepatitis C virus rapid tests in detecting antibodies in general population.

Background: Evaluation of clinical performance of the anti-hepatitis C virus (HCV) rapid tests were carried out mostly in chronic hepatitis C patients and in individuals at high risk of HCV infection.
Methods: The aim of this study was to evaluate the performance of OraQuick and Wantai rapid tests on archived serum samples from 1408 individuals (mean age 46, range 18-90; 65% female) recruited with a systematic sampling procedure during a general population survey.
Results: The analysis of samples by Ortho HCV 3.0 ELISA and Cobas Taqman HCV RNA assays resulted in 69 anti-HCV antibody positive sera, including 42 HCV RNA positive (group 1) and 27 HCV RNA negative (group 2) samples. The performance of rapid tests was evaluated on the 69 anti-HCV positive (group 1+2) and 206 (OraQuick) and 198 (Wantai) anti-HCV negative sera, randomly selected from the 1339 anti-HCV negative samples. The OraQuick and Wantai rapid assays showed a sensitivity in group 1 of 92.9% and 90.5%, respectively. The sensitivity in group 2 was 40.7% and 51.9%, respectively. The anti-HCV antibodies signal/cutoff mean value was the only parameter that statistically differed between group 1 and group 2 individuals (P<0.0001). Further, 3 (OraQuick) and 4 samples (Wantai) from group 1, with very low HCV RNA level (<25 UI/mL), were misdiagnosed by rapid assays as false negative.
Conclusions: The proportion of infections with low level of viremia and the risk associated with rapid assay failure remained to be carefully estimated in general population.