Table 3.

Outcome of diagnostic testing for HCV infection using core antigen detection (HCV-Ag) compared to gold standard PCR for HCV RNA

Outcome	Result (n)*
True positive	121
False negative	7
False positive	0
True negative	67
Test characteristic	Result (%)
Sensitivity	94.5
Specificity	100
Positive predictive value	100
Negative predictive value	90.5

*Results pertain to all HCV-antibody individuals in ‘Group 2’, based on samples that were tested with assays for both HCV-Ag and HCV RNA, defined as follows: true positives (HCV-Ag + and HCV RNA+); false negatives (HCV Ag- and HCV RNA+); false positives (HCV Ag + and HCV RNA-); true negatives (HCV Ag- and HCV RNA-). These groups are also shown in Fig. 4a. Threshold for positive HCV-Ag was 3 fmol/L