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:
6/03/031 Hepatitis C –Update Laboratory Issues Hema Kapoor MD. SM Virology Section Manager Bureau of Laboratories Michigan Department of Community Health
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
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
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
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
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
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
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 _
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).
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).
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
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
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…
6/03/0315 Advantages and Impact ?
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
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