Dufour et al developed an algorithm for evaluating enzyme immunoassay (EIA) results for antibodies to hepatitis C virus (HCV). This can be used to efficiently evaluate a patient for HCV infection. The authors are from the Veterans Affairs Medicial Center, National Institute of Digestive, Diabetes, and Kidney Diseases, and George Washington University in Washington, D.C.
Parameters:
(1) EIA test results, including signal-to-cutoff ratio (S/C) if positive (see previous section)
(2) RIBA (recombinant immunoblot assay)
(3) frequency of elevated ALT serum levels (ALT pattern)
(4) HCV RNA testing
(5) decision to treat or not
EIA S/C Ratio |
Interpretation |
Action |
<= 1.0 |
negative |
none; diagnose as negative |
1.01 – 3.79 |
low positive |
perform RIBA |
>= 3.80 |
high positive |
review ALT pattern |
RIBA Result |
Action/Interpretation |
negative |
negative for HCV; EIA false positive |
indeterminate |
perform HCV RNA |
positive |
perform HCV RNA |
ALT Pattern |
Decision to Treat |
Action/Interpretation |
<= 1 increased |
NA |
perform HCV RNA |
>=2 increased (multiple) |
no |
presume positive; no further testing needed |
>=2 increased (multiple) |
yes |
perform HCV RNA |
Purpose: To evaluate a patient with possible viral hepatitis C (HCV) using the testing algorithm of Dufour et al.
Specialty: Infectious Diseases, Gastroenterology
Objective: laboratory tests, criteria for diagnosis
ICD-10: B17.1, B18.2,