Table 1 Comparison of diagnostic laboratory tests used to detect exposure and activity of HCV infection

Benefits

♦ Widely available;

♦ Inexpensive;

♦ Much experience and data for use as first-line approach to screening for HCV exposure (underpins many old seroprevalence studies).

♦ Diagnostic of active infection (not past exposure);

♦ Improved specificity and reduced window period compared to HCV-Ab [14, 29, 42,43,44,45].

♦ Accepted gold-standard diagnostic test for active infection (not past exposure);

♦ Allows quantitative monitoring of viraemia; useful for monitoring therapy;

♦ Genome amplification allows other information to be ascertained (e.g. genotype; drug resistance);

♦ Can potentially be applied to dried blood spots (DBS).

Challenges

♦ Subject to inter-assay variability and a variable rate of false positive results [46, 47]; false positive has been associated with ethnicity [48, 49], age [48], raised IgM and erythrocyte sedimentation rate (ESR) [46], auto-antibodies [50], and prosthetic devices [51];

♦ Test of exposure, not of active infection, so should be followed up with a more specific diagnostic test.

♦ Not universally available;

♦ More expensive than HCV-Ab;

♦ Not consistently regarded as sufficiently sensitive to replace PCR.

♦ Not universally available;

♦ Expensive: beyond the financial reach of many resource-limited settings.