Page 31 - The Flying Publisher Guide to Hepatitis C Treatment

Patients’ monitoring during and after treatment | 31

positive results, due to passive antibodies transfer from the
mother).
Nucleic acid testing (NAT) – detection of presence and/or
amount (viral load – VL) of HCV RNA in the blood, reflects the
actual viral replication. These tests are the hallmark of HCV
diagnosis in both antibody-positive and negative patients, with
unexplained ALT elevations or liver disease documented by liver
biopsy (LB). A high VL is a negative predictor of therapeutic
success. Sequential VL measurements with the same method
during treatment (at weeks 4, 12, 24/48) and 6 month after
treatment completion inform response-guided therapy (RGT).

Table 2.1 – Blood tests for hepatitis C
Test/Type Application Comments
EIA Indicates past or present Does not differentiate
(enzyme immunoassay) infection between acute and
chronic infection
All positive EIA results should be checked with a supplemental HCV RNA
assay:
HCV RNA qualitative Detects virus as early as 1-2 Presence of circulating
(RT-PCR) weeks after infection. HCV RNA might be
Useful for reduction of intermittent
residual risk associated to
transfusions*
A single negative RT-PCR is not conclusive
HCV RNA quantitative Determines concentration Useful for assessing the
(Real-time PCR) of HCV RNA (VL) response to therapy
HCV RNA genotyping Groups isolates of HCV Determines the length
based on major genetic of treatment and
types and subtypes prediction of SVR rate
* screening by Versant™ (Siemens Health Care Diagnostics) and Procleix™ HIV-
1/HCV assays (Gen-Probe).
Determination of HCV genotype. The molecular
characterization of genotypes and subtypes of HCV is
particularly important for the response to treatment and disease
prognosis (Scott 2007). There are 6 major genotypes of HCV and
more than 50 subtypes.