Performance evaluation of two supplemental confirmatory assays of hepatitis C virus antibody

Background: The overall relative change in Hepatitis C virus (HCV) reporting incidences was 1.16 in China recently, which exhibited increasing trend in most provinces. Screening tests for HCV antibodies are prone to generate higher false positivity in low-risk populations. The aim of this study was to compare the performance of two HCV supplemental confirmatory assays CWT (Wantai Biological Pharmaceutical Co., Ltd, Beijing, China) and RIBA HCV 3.0 SIA (RIBA 3.0). Methods: We selected 530 reactive specimens identified by two rounds of anti-HCV enzyme-linked immunosorbent assays (EIA) to carry out CWT and RIBA 3.0 supplemental tests simultaneously. Then the parallel testing results were evaluated as positive, indeterminate and negative, and made comparative analysis. Results: There were 182 and 160 confirmed positive samples for CWT and RIBA 3.0 respectively, of which 128 (24.2%) cases were common positive. the positive rate of CWT (34.3%) was significantly higher than RIBA 3.0 (30.2%) (P<0.01). And the common negative and indeterminate specimens were 156 (29.4%) and 53 (10%). The remaining 193 (36.4%) specimens had inconsistent results. The 182 CWT positive specimens included 35 indeterminate specimens (22%, 35/164) and 18 negative specimens (8.7%, 18/206) of RIBA 3.0. The diagnostic results of RIBA 3.0 and CWT supplementary assays were generally consistent (kappa =0.445, P<0.01). Conclusions: This study suggested that RIBA 3.0 and CWT each had its own genetic sequences of target peptides on HCV confirmatory tests and the latter might be more applicable for China’s current HCV epidemic strains. The number of positive cases confirmed by CWT is higher than that of RIBA 3.0, which corroborates this.