The Evaluation Of Anti-HCV Testing Strategies

BackgroundHepatitis C is caused by hepatitis C virus, which seriously impact on human health and the quality of life. Due to no significant clinical symptom, the diagnostic of hepatitis C mainly based on the laboratory test results. The laboratory test results of HCV can be used for blood screening, epidemic monitoring, clinical diagnosis and so on, which include screening tests and supplement tests. Screening test usually uses the ELISA method, and supplement test is WB and PCR methods. ELISA method is simple and cheap; with suitable testing strategies could be used foe different test purpose. Before widely used, testing strategies should be evaluated to ensure the reality and reliability of the test result. UNAIDS and WHO recommend three steps to evaluate the testing strategies, which had already been completed in China, so this study is focus on the third step of the evaluation. Meanwhile, to make assurance of proper use of the testing strategies, the assessment of test methodology is studied.ObjectiveTo evaluate the testing strategies for epidemic monitoring and clinical diagnosis; Evaluating15anti-HCV enzyme-linked immunosorbent assay reagent kits and8colloidal gold reagent kits.MethodsThe sample and the test results of sentinel points were collected from2010HIV/HCV sentinel points of four provinces, include6kinds of people with different infection ways. Retest the samples by the testing strategies, making ELISA+WB as the standard results, calculate the sensitivity, specificity, positive predict value and negative predict value to evaluate the testing strategies. Use the Kappa analysis to analyze the repeatability of the testing strategies for epidemic monitoring.Fifteen anti-HCV ELISA kits and eight anti-HCV Colloid Gold kits including domestic and foreign were evaluated by five serum panels including AIDS Reference Lab master panel, BBI seroconversion panel, AIDS Reference Lab cross-reacting panel, AIDS Reference Lab characteristics panel and AIDS Reference Lab precision control material. Evaluation indexes contained sensitivity, specificity, positive predict value negative predict value mean delayed days and so on.ResultsThe sensitivity, specificity, PPV and NPV of the testing strategies for epidemic monitoring respectively is98.59%、99.97%、99.29%、99.94%. The sensitivity of the population with low prevalence is litter lower than others. The use of the testing strategies are non different in6populations with different infectious ways. The agreement ratio between the test results of sentinel point and this study is99.78%.There are two methods of the clinical diagnosis testing strategies, one is screening plus confirmation testing, and the other is S/CO alternative strategy. The sensitivity, specificity, PPV and NPV of the screening plus confirmation testing strategy respectively is96.49%、100%、93.22%、93.94%, which are higher than testing by the screening test only. The false-positive ration can reduce by about10%. To use the S/CO alternative strategy, the threshold of Wantai ELISA kit and Xinchuang ELISA kit respectively is5.0and4.0. With those threshold, the sensitivity and specificity are all higher than95%.The coincidence rates of both positive and negative samples of the ELISA kits are more than39/40; the coincidence rates of positive samples of the Colloid Gold kits are lager than33/40, while the coincidence rates of negative samples are between39/40to40/40. Based on seroconversion panel, mean delayed days of the fifteen ELISA kits are between8to19days. There are no cross-reaction between anti-HCV, anti-HIV, HBsAg and anti-TP for all HCV ELISA and Colloid Gold kits. For the AIDS Reference Lab characteristics panel, the detection rate of ELISA kits are between2/6-6/6, and the Colloid Gold kits are between0/6-3/6. The CV between different wells for each ELISA kits are between3%～25%, and the CV between different96well plates are between2%-50%. ConclusionThe application effect of the epidemic monitoring strategy and clinical diagnosis strategies are good in China. There’s no significant different used in the population with different infectious ways, so these strategies can be generally used.The sensitivity and specificity of15anti-HCV ELISA kits are both high. The anti-HCV Colloid Gold kits have high sensitivities, but the specificities are different. Anti-HCV ELISA was applicable to screening test in general people. The sensitivity of anti-HCV Colloid Gold kits needed to be further improved.