Evaluation of Architect anti-HCV Signal to Cutoff Ratios for Predicting Hepatitis C Viremia Using COBAS AmpliPrep/COBAS TaqMan HCV Quantitative Test.

BACKGROUND: The aim of the study is to evaluate the significance of the Architect anti-HCV signal to cutoff (S/CO) ratios for predicting hepatitis C viremia and determine the optimal S/Co ratio value for Architect anti-HCV assay. METHODS: The results of patients who underwent HCV RNA quantitative assays because of positive anti-HCV from January 2015 to August 2019 were retrospectively analyzed, including S/Co ratio values, HCV RNA quantitative results, alanine aminotransferase (ALT), and aspartate transaminase (AST) values. Binary logistic regression and Spearman's correlation coefficient were used to analyze the collected data. Receiver-operating characteristics curve (ROC) was applied to analyze the predicting values of the indexes. RESULTS: In total, 811 patients were included in our study and HCV viremia was detected in 342 (42.1%) patients. There is no correlation between anti-HCV S/CO ratio and HCV RNA level. The samples with an S/Co ratio between 1 and 4 (271/271, 100%) were all HCV RNA negative. The area under the ROC curve of anti-HCV S/CO ratio was 0.8714 and the maximal Youden index was 0.681 at an optimal cutoff S/CO ratio value of 8.99. CONCLUSIONS: With the cutoff value of 1.0, the Architect anti-HCV assay showed excellent sensitivity but poor specificity in predicting HCV viremia. An S/Co ratio of 8.99 was optimal for further confirmation testing of HCV viremia.