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6/03/031 Hepatitis C –Update Laboratory Issues Hema Kapoor MD. SM Virology Section Manager Bureau of Laboratories Michigan Department of Community Health.

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Presentation on theme: "6/03/031 Hepatitis C –Update Laboratory Issues Hema Kapoor MD. SM Virology Section Manager Bureau of Laboratories Michigan Department of Community Health."— Presentation transcript:

1 6/03/031 Hepatitis C –Update Laboratory Issues Hema Kapoor MD. SM Virology Section Manager Bureau of Laboratories Michigan Department of Community Health

2 6/03/032 Laboratory Tests for HCV Available at MDCH  Screening tests EIA  Supplemental RIBA ( Recombinant immunoblot assay) Nucleic acid Amplification tests Additional Tests Available Commercially  CIA (Chemiluminescence's immunoassays)  Quantitative RNA Tests  Genotyping  Core Protein Antigen

3 6/03/033 Laboratory Algorithm for HCV Testing Screening Test for Anti-HCV* Negatives REPORT ORPositive Indeterminate Negative RIBA for anti-HCV REPORTREPORTREPORT Positive EIA/CIA Test Nucleic acid test for HCV RNA Positive REPORT Positive Negative REPORT Indeterminate REPORTREPORT Negative RIBA for anti-HCV * HCV EIA 2.0 ( Abbott), HCV version 3.0 ELISA( Ortho), VITROS Anti-HCV

4 6/03/034 Anti-HCV EIA False Positivity* by Population Prevalence Prevalence of HCV Infection 90% Percent False Positive HCWs Military STD Clients Pregnant Women Dialysis Transfused Injecting Drug Users NANB Hepatitis ALT * As judged by RIBA or NAT Source: CDC

5 6/03/035 CDC

6 6/03/036 Consistency of Reported Anti-HCV Results  Screening test positive signal to cutoff ratios*  Results above the cutoff should predict a true antibody positive  Only results below the cutoff would require supplemental antibody testing  Cutoff should perform the same regardless of the population being tested * Not intended for use in screening donors as provided by FDA guidance

7 6/03/037 Anti-HCV Test Versions Evaluated Ortho 3.0, RIBA 3.0 N=25,532  High-risk  Hemodialysis patients  STD patients  HCWs  General population (NHANES IV) VITROS Anti-HCV (Ortho), RIBA 3.0 N=1326  Clinical specimens (Hospital-based patients)  Low prevalence populations Abbott 2.0, RIBA 3.0 N=8,754  STD patients  Students

8 6/03/038 EIA Signal to Cutoff Ratio  Signal: Optical density (OD) value of the sample being tested.  Cut off: Mean absorbance of negative Control plus Example:Sample ODCutoff ODS/CO s/cut off (s/co)-  3.8

9 6/03/039 Proportion of Anti-HCV EIA* Screening Test Positive Results Testing RIBA Positive by Average S/Co Ratio Source: CDC. MMWR 2003;52 (No. RR-3). 4.3% 2.2% 0% * EIA 2.0 or EIA 3.0 Prevalence _

10 6/03/0310 * VITROS Anti-HCV assay Proportion of Anti-HCV CIA* Screening Test Positive Results Testing RIBA Positive by S/Co Ratio (n = 142) > (n = 1184) Screening-test-positive s/co ratio Prevalence Source: CDC. MMWR 2003;52 (No. RR-3).

11 6/03/0311 Proportion of Anti-HCV EIA RR Results Requiring RIBA Based on S/CO Ratio <3.8 and HCV Prevalence Source: CDC. MMWR 2003;52 (No. RR-3).

12 6/03/0312 Use of EIA/CIA S/CO Ratio to Determine Need for Additional Routine Testing  Screening-test-positive samples with s/co ratios >3.8*/8 † can be reported based on screening test  >95% will be RIBA positive.  Screening-test-positive samples with s/co <3.8*/8 † require additional testing because most are falsely positive.  In high prevalence populations few in this range.  Limits cost while improving accuracy of reported results. * Applies only to Ortho 3.0 or Abbott 2.0 EIA † Applies only to Ortho Vitros CIA

13 6/03/0313 Laboratory Algorithm for Anti-HCV Testing and Result Reporting: MMWR 2003 Screening Test for Anti-HCV Negatives REPORT Positive Indeterminate Negative RIBA for anti-HCV REPORTREPORTREPORT Positives with high s/co ratios REPORT All positives OR Positives defined by s/co ratios* NegativePositiveIndeterminateNegative REPORT RIBA for anti-HCV REPORTREPORT * HCV EIA 2.0( Abbott), HCV version 3.0 ELISA (Ortho), VITROS Anti-HCV Source: CDC. MMWR 2003;52 (No. RR-3). OR Positive Nucleic acid test for HCV RNA Positives with low s/co ratios REPORT

14 6/03/0314 Repeatedly Reactive Anti HCV Supplementary serological confirmation testing was not performed on this specimen with a high serum to cut-off ration in accordance with CDC guidelines (MMWR, 52 RR03; 1-16). Appx 95% of specimens with a high serum to cut-off ratio confirm positive when tested in supplementary tests. The serum to cutoff ratio is not related to severity of disease or acute/chronic phase of infection. Supplementary testing is available only after consultation with Dr. Jeff Massey…

15 6/03/0315 Advantages and Impact ?

16 6/03/0316 Advantages of Revised Laboratory Guidelines  Standard reporting of anti-HCV positive results.  Reliable Interpretation of anti-HCV results.  Ensure positive patients receive follow-up  Prevent unnecessary evaluation of “false-positives”  Low cost of additional testing  Better understanding of performance and interpretation

17 6/03/0317 Implications  Patients and physicians can reliably interpret results  Further clinical evaluation limited to true positives  Limit psychological stress on patients who test falsely positive  Substantially improve ability to establish public health surveillance systems to monitor effect of prevention and intervention activities


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