HCV Diagnostics by Tp10cwox

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									         HCV
      Diagnostics
Hepatitis C Training Conference
          April 9, 2008
        History of HCV Testing
• First tests licensed by the Food and Drug
  Administration in 1990
• Since 1990 new versions of these and other
  FDA- approved anti HCV tests have been used
  for
   – Clinical Diagnosis of HCV
   – Screening of asymptomatic persons
                Testing Rationale
•    Testing for HCV infection by using anti-HCV is
     performed for
    1) Clinical diagnosis of patients with signs or
       symptoms of liver disease
    2) Management of occupational and perinatal
       exposures
    3) Screening asymptomatic persons to identify HCV-
       infected persons who should receive counseling and
       related to the persons tested is often lacking, and
       even persons with risk factors for HCV infection
       might be at sufficiently low enough risk for infection
       that there screening tests could be falsely positive
       (e.g. health care professionals-risk but low
       prevalence)
         Approved Testing Kits
• Comprised of
  – Two enzyme immunoassays (EIA)
     • Abbot HCV EIA 2.0
     • ORTHO HCV Version 3.0 ELISA


  – One enhanced chemiluminescence immunoassay
    (CIA)
     • VITROS


• All of the above immunoassays use HCV-
  encoded recombinant antigens
  Available Supplemental Tests

• Tests include
  – Serologic anti-HCV assay
     • Nucleic acid test (NAT)
        – Qualitative detection of HCV-RNA
           » AMPLICOR Version 2
           » COBAS AMPLICOR Version 2
     • Recombinant immunoblot assay (RIBA)


  The Laboratory used determines the type of
   test performed
Interpreting Antibody to Hepatitis
        C Virus (anti-HCV)
           Test Results
                   Anti-HCV -Positive

• Defined as
     1) Anti-HCV screening test positive*
                  AND
      Recombinant immunoblot assay (RIBA)-
            positive
                  OR
      Nucleic acid test (NAT) – positive

  *Interpretation of screening immunoassasy test results based on criteria provided by
      the manufacturer
          Anti-HCV -Positive
2) anti-HCV screening test positive, NAT-
  negative, RIBA- positive
– An anti-HCV positive result indicates past or
  current HCV infection.
  • An HCV RNA-positive result indicates current
    (active) infection BUT the significance of a single
    HCV RNA-negative result is unknown; it does not
    differentiate intermittent viremia from resolved
    infection
             Anti-HCV-Positive

• All anti-HCV positive persons should
  receive
  – Counseling
  – Undergo medical evaluating, including
    additional testing for the presence of virus and
    liver disease
     • Anti-HCV testing usually does not need to be
       repeated after a positive anti-HCV result has been
       confirmed
                    Anti-HCV -Negative
•    Defined as:
    1) Anti-HCV screening test negative*
                                       OR
    2) Anti-HCV screening test positive, RIBA-
        negative
                                       OR
    3) Anti-HCV screening test positive, NAT-
        negative, RIBA-negative

    *Interpretation of screening immunoassasy test results based on criteria provided by
          the manufacturer
            Anti-HCV- Negative

• An anti-HCV person is considered
      uninfected
• No further evaluation or follow-up for HCV
  is required, unless recent infection is
  suspected or other evidence exists to
  indicate HCV infection
     • Abnormal liver enzyme levels in an immuno-
       compromised person
     • A person with no other etiology for their liver
       disease
       Anti-HCV- Indeterminate

• Defined as:

  Anti-HCV screening test positive, RIBA-
   indeterminate
       Anti-HCV- Indeterminate
• An indeterminate anti-HCV result indicates
  that the HCV antibody status cannot be
  determined
  – Can indicate a false positive anti HCV
    screening test result, the most likely
    interpretation among those at low risk for HCV
    infection; such persons are HCV RNA-
    negative
  – Can occur as a transient finding in a recently
    infected person who is in the process of
    seroconversion: such persons usually are
    HCV RNA -positive
       Anti-HCV- Indeterminate
  – Can be persistent finding among persons
    chronically infected with HCV; such persons
    usually are HCV RNA -positive


• If NAT is not performed, another sample
  should be collected for repeat anti-HCV
  testing (> 1 month later)
          Signal to Cutoff Ratios
• Analysis of enzyme immunoassay and
  chemiluminescence assay data indicates that
  s/co ratios can be used to predict supplemental
  test-positive results
• A specific s/co ratio can be identified for each
  test that would predict a true antibody-positive
  result (as defined by the results of supplemental
  testing) ≥95% of the time, regardless of the anti-
  HCV prevalence or characteristics of the
  population being tested.
                                                                            Signal-to-cut—off ratio
                                                                              predictive of a true
 Screening test kit name   Manufacturer            Assay Format
                                                                            positive ≥ 95% of the
                                                                                      time



Ortho HCV Version 3.0
                                                       EIA
ELISA                         Ortho                                                 ≥ 3.8
                                              (Enzyme Immunoassay)
Test System


                                                       EIA
Abbott HCV EIA 2.0           Abbott                                                 ≥ 3.8
                                              (Enzyme Immunoassay)


                                                       CIA
VITROS Anti-HCV               Ortho            (Chemiluminescennt                   ≥ 8.0
                                                 Immunoassay)


                                                       MEIA
AxSYM Anti-HCV               Abbott                                                 ≥ 10.0
                                           (Microparticle Immunoassay)


                                                      CMIA
Architect Anti-HCV           Abbott       (Chemiluminescent Microparticle           ≥ 5.0
                                                  Immunoassay)


                                                       CIA
Advia Centaur HCV             Bayer            (Chemiluminescennt                   ≥ 11.0
                                                 Immunoassay)
                                 What Next?
• ECHO Hepatitis C Lab
     – Obtain or review following minimal “markers” for hepatic
       decompensation:
     – Liver Panel (ALT/AST)
     – Albumin, Total Protein
     – Total/Direct Bilirubin
     – Uric Acid
     – Cholesterol (low)
     – PT/INR
     – Complete CBC with platelet count


•   If presence of Hepatitis C virus is confirmed, proceed to Pre-Treatment Work-Up after
    consultation with HCV Project ECHO Team if needed. Initiate Patient Education process: Use
    Hepatitis C Patient Teaching Tool, (Attachment B).
   PRE-TREATMENT LAB WORKUP
• Obtain following labs if not present in chart or
  not current within past 60 days:
      • CBC with Differential, platelets, Bun, glucose, NA, K+,
        Chloride, CO2, Alk Phos
      • PT, PTT, INR
      • Bilirubin Direct, Indirect, Total, ALT, AST, Uric Acid, Albumin,
        Lipids.
      • Alk Phos
      • Alpha Fetoprotein
      • Fe, TIBC, Ferriten
      • TSH, T4, T3
      • UA
      • Urine or serum pregnancy test ( ♀ of childbearing capacity)
                References

• CDC.gov
• Project Echo Hepatitis C Clinical Guidelines

								
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