Relationship between hepatitis C virus (HCV) IgG index values and quantitative HCV RNA results in HCV IgG-reactive serum samples

Centers for Disease Control guidelines recommend hepatitis C virus (HCV) RNA testing of all HCV IgG-reactive samples, although earlier studies found that IgG-reactive samples with low indices were negative in qualitative RNA assays. To determine if previous study results could be confirmed using current real-time RT-PCR technology, we investigated the relationship between HCV IgG index (Ortho VITROS) and quantitative HCV RNA results (cobas HCV) for 2368 consecutive IgG-reactive sera. Results were segregated into Low (1.00?16.0), Medium (16.1?30.0), and High (>30.0) IgG index groups. Although median viral load (VL) of RNA-positive samples was similar in all 3 groups, the percentage with low VL (1.18?4.16 log IU/mL) was increased for the Low group. Further analysis of the Low group revealed that 23 of 370 (6%) samples with IgG indices ?8.00 were RNA-positive, and 13/23 (57%) had low VL. Our analysis supports the Centers for Disease Control recommendation to test all HCV IgG-reactive sera for HCV RNA. ? 2021 Elsevier Inc. All rights reserved.

Automated summary

The study found that some samples with low HCV IgG indices were still HCV RNA positive, with low viral loads. Therefore, it supports the recommendation to test all HCV IgG-reactive sera for HCV RNA.