Threshold value of the anti-HCV test in the diagnosis of HCV infection

Abstract

Introduction: In the diagnosis of hepatitis C virus (HCV) infection, the first step is screening for anti-HCV antibodies, and positive results are generally confirmed with nucleic acid amplification tests. Recent studies have reported that more compatible results have been obtained with the HCV RNA test using signal to cut-off (S/Co) values >1, which are the routine reactivity threshold for the anti-HCV enzyme immunoassay (EIA) test. The aim of this study was to determine the most appropriate S/Co value for the anti-HCV test, predicting HCV infection. Methodology: Comparisons were made between results of 559 patients who underwent anti-HCV with ECLIA method and HCV RNA tests with real-time polymerase chain reaction (PCR) method. By accepting the HCV-RNA test as the gold standard for HCV infection, the sensitivity, specificity and predictive values of the ECLIA test were determined and statistical “receiver operating characteristic” (ROC) analysis was applied to determine the most appropriate threshold. Results: Between January 2013 and April 2018, a total of 81,203 serum samples were examined. Of 559 anti-HCV positive patients, HCV RNA positivity was determined in 214 (38.2 %). According to the ROC analysis results, the most appropriate S/Co value was determined as 12.27, at which sensitivity was 94.4 %, and specificity 97.4 %. The positive and negative predictive values were calculated at the high rate of 95.7% and 96.6% respectively. Conclusions: The results of this study investigating the anti-HCV reactivity values which could be used in the diagnosis of HCV infection determined the most appropriate value to be 12.27.