The role of a two-assay serological testing strategy for anti-HCV screening in low-prevalence populations

HCV screening depends mainly on a one-assay anti-HCV testing strategy that is subject to an increased false-positive rate in low-prevalence populations. In this study, a two-assay anti-HCV testing strategy was applied to screen HCV infection in two groups, labelled group one (76,442 people) and group two (18,415 people), using Elecsys electrochemiluminescence (ECL) and an Architect chemiluminescent microparticle immunoassay (CMIA), respectively. Each anti-HCV-reactive serum was retested with the other assay. A recombinant immunoblot assay (RIBA) and HCV RNA testing were performed to confirm anti-HCV positivity or active HCV infection. In group one, 516 specimens were reactive in the ECL screening, of which CMIA retesting showed that 363 (70.3%) were anti-HCV reactive (327 positive, 30 indeterminate, 6 negative by RIBA; 191 HCV RNA positive), but 153 (29.7%) were not anti-HCV reactive (4 positive, 29 indeterminate, 120 negative by RIBA; none HCV RNA positive). The two-assay strategy significantly improved the positive predictive value (PPV, 64.1% & 90.1%, P < 0.05). In group two, 87 serum specimens were reactive according to CMIA screening. ECL showed that 56 (70.3%) were anti-HCV reactive (47 positive, 8 indeterminate, 1 negative by RIBA; 29 HCV RNA positive) and 31 (29.7%) were anti-HCV non-reactive (25 negative, 5 indeterminate, 1 positive by RIBA; none HCV RNA positive). Again, the PPV was significantly increased (55.2% & 83.9%, P < 0.05). Compared with a one-assay testing strategy, the two-assay testing strategy may significantly reduce false positives in anti-HCV testing and identify inactive HCV infection in low-seroprevalence populations.

Multicenter evaluation of EIAs and CLIAs in the detection of hepatitis C virus antibody among blood donors in China

Background: Recent data on anti-HCV screening assays among large population of blood donors is limited. The present study aimed to perform a multicenter evaluation of EIAs and CLIAs for detection of anti-HCV among blood donors in 16 different Chinese blood establishments.Methods: A total of 1,309 samples including 582 anti-HCV screening negatives and 727 positives collected from 15 blood establishments all over China. Ten different anti-HCV assays (eight EIAs and two CLIAs) were evaluated in 16 different blood centers/banks. Confirmatory testing was performed using recombinant immunoblot assay and HCV RNA tests.Results: The plasma panel contained 963 negative samples, 261 positives, and 85 indeterminate samples, based on the results of confirmatory test. False positive rate of screening tests was 39.67% (382/963) and the positive prediction value was only 35.76% (260/727). Among ten anti-HCV assays, Roche and InTec had the highest sensitivity (98.47%), while KHB and Wantai (indirect) had the highest specificity (99.23%). Then we analyzed the combined performance of these assays with two assays’ strategy widely used in China: Ortho or Abbott together with InTec could find all the true positives and Wantai (indirect) with Livzon (sandwich) got a highest specificity of 97.80%. Indeterminate samples showed quite different signal to cutoff (S/CO) ratios tested by Roche compared with confirmed positives (4.84 vs 19.36, p<0.0001), and higher S/CO ratios than confirmed negatives (4.84 vs 2.94, p=0.020). Conclusion: False reactivity in anti-HCV screening should be treated as urgent issue. RIBA indeterminate donations may be a special group, while it still worth to be further studied.

Evaluation of HCV RNA by PCR and Signal-to-Cutoff Ratios of HCV Antibody Assays for Diagnosis of HCV Infection

Objective In this study, we assessed whether a hepatitis C virus (HCV) RNA test could replace recombinant immunoblot assay (RIBA) and reduce unnecessary supplemental tests as the signal-to-cutoff (S/Co) ratio from anti-HCV antibody (Ab) tests. Methods Anti-HCV Ab tests were performed to screen for HCV infections, and RIBA and real-time polymerase chain reaction were performed for HCV RNA to confirm HCV infection. Receiver operating characteristic curves were evaluated to determine the optimal S/Co ratios for predicting HCV infection. Results The cutoff value for the S/Co ratio was 3.63 for predicting RIBA results and 10.6 for predicting HCV RNA results. Our data suggested that an S/Co ratio ≥10.6 indicated a high risk of active HCV infection. An S/Co ratio of 3.63 to 10.6 needed further evaluation and repeat HCV RNA testing. No further testing was required for S/Co ratios &lt;3.63 or ≥10.6. Conclusion We determined that the S/Co ratio of the anti-HCV Ab test provides useful information to confirm HCV infections, including the need for further laboratory testing or clinical follow-up.

Multicenter evaluation of EIAs and CLIAs in the detection of hepatitis C virus antibody among blood donors in China

Background: Recent data on the evaluation of screening serological assays on anti-HCV among a large sample of blood donors is lacking. The present study aimed to perform a multicenter evaluation of EIAs and CLIAs for detection of anti-HCV among blood donors in 16 different Chinese blood establishments.Methods: A total of 1,309 samples containing 582 anti-HCV screening negatives and 727 positives collected from 15 blood establishments all over China. A total of 10 different anti-HCV assays (8 EIAs and 2 CLIAs) were evaluated in 16 different blood centers/banks. Confirmatory testing was performed using recombinant immunoblot assay and HCV RNA tests.Results: There were 963 true negatives, 261 positives, and 85 indeterminate samples. False positive rate of screening testing was 39.67% (382/963) and the positive prediction value was only 35.76% (260/727). Roche and InTec had the highest sensitivity (98.47%) and KHB and Wantai (indirect EIA) had the highest specificity (99.23%). Ortho/Abbott together with InTec could detect all the true positives. Among samples with discrepant results by different assays, indeterminate samples showed quite different S/CO ratios detected by Roche compared with confirmed positives (4.84 vs 19.36, P<0.0001), and higher signal to cutoff (S/CO) ratios than confirmed negatives (4.84 vs 2.94, P=0.020). However, there was no difference among the three groups when detected by Abbott. When S/CO ratio went to 8.2 on Roche and 4.2 on Abbott, the PPV could achieve more than 95%.Conclusion: False reactive problem of anti-HCV screening should be solved urgently. RIBA indeterminate donations may be a special group, should be further studied.

Prevalence of Hepatitis B, C, and D among Thalassemia patients in Sulaimani Governorate

Infectious diseases are the leading cause of mortality worldwide, with hepatitis viruses in particular making global impact on socioeconomic development and this infection remains a serious public health issue. This study was performed to investigate the prevalence of Hepatitis B, C and D among multi-transfused risk groups in Sulaimani Governorate, 120 major thalassemic patients were tested by serological and enzyme-linked immunosorbent assay (ELISA) technique and Recombinant ImmunoBlot Assay (RIBA) test was done as a confirmatory test for all HCV ELISA positive patients. It was observed that the prevalence of HCV was higher (29.1%) comparing to HBV (22.5%) and HDV (3.3%). The prevalence of HCV-HBV coinfection was (5%), HCV-HBV-HDV coinfections were (0.83%). Statistical analysis showed that the age was significantly effective on the prevalence of HBV (p = 0.009), parenteral medication users showed a significant relation with HBV and HCV prevalence (p = 0.03 and 0.041) respectively. The blood transfusion frequency was significantly related to HBV and HCV prevalence (p = 0.042 and 0.035) respectively. It was noticed that vaccination significantly related to HBV prevalence among thalassemic patients (p = 0.002).

Reflex threshold of signal-to-cut-off ratios of the Elecsys anti-HCV II assay for hepatitis C virus infection

Introduction: Fast screening tests for hepatitis C virus (HCV) antibody often give false-positive results. Signal-to-cut-off (S/Co) ratios were suggested to be used as reflex confirmation of anti-HCV. The Elecsys Anti-HCV II assay is an effective test for the detection of hepatitis C, but no S/Co cutoff has been reported. The aim of this study was to determine the S/Co ratio threshold of anti-HCV test using Elecsys Anti-HCV II screening and supplemental recombinant immunoblot assay (RIBA) test results as the gold standard. Methodology: A total of 36,341 serum samples were tested for HCV antibody using the Elecsys Anti-HCV II assay and 276 positive samples were then tested with supplemental RIBA (Mikrogen recomLine HCV IgG strip immunoassay). Receiver operation curve (ROC) analysis was used to determine the cutoff, sensitivity, and specificity of the optimal S/Co ratio. Results: The Elecsys Anti-HCV II assay was positive (S/Co ratio ≥ 1) in 288 of the 36,341 samples (0.79%). RIBA testing on 276 of these 288 positive samples showed that all but one of 44 samples with an S/Co ratio of ≥ 1 and < 10 were negative, whereas the vast majority of samples (223/232, 96.1%) with an S/Co ratio ≥ 10 were positive. ROC analysis revealed that an optimal S/Co ratio cut-off value was 12.27. Conclusions: An S/Co ratio of 12.27 obtained with the Elecsys Anti-HCV II assay could be used as reflex confirmation of anti-HCV tests.