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Supplemental Testing of Donors for HIV and HCV . September 18, 2003 BPAC Meeting Robin Biswas, M.D. Indira Hewlett, Ph.D. FDA/CBER/OBRR/DETTD. Supplemental Testing of Donors for HIV and HCV. Discussion of the utility of various supplemental testing strategies to

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Supplemental Testing of Donors for HIV and HCV

September 18, 2003 BPAC Meeting

Robin Biswas, M.D.

Indira Hewlett, Ph.D.

FDA/CBER/OBRR/DETTD


Supplemental testing of donors for hiv and hcv l.jpg
Supplemental Testing of Donors for HIV and HCV

  • Discussion of the utility of various

    supplemental testing strategies to

    CONFIRM A REPEATEDLY REACTIVE ENZYME IMMUNOASSAY (EIA) SCREENING TESTRESULT

    for

    - HIV using Western Blot, Nucleic

    Acid Tests, second EIA, and for

    - HCV using RIBA, Nucleic Acid

    Tests, high signal-to-cutoff ratio in

    screening EIA


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Reason for Discussing HIV and HCV Supplemental Testing of Donors

  • 1998 MMWR recommended that, in the clinical

    laboratory, diagnostic setting, an anti-HCV reactive

    screening test result be verified by a more specific

    supplemental test, e.g., RIBA.

  • 2003 MMWR repeats and emphasizes

    the desirability of performing supplemental

    testing on screen reactives. It offers an option for

    reporting positive test results using high signal-to-

    cutoff ratios in the screening test, in the clinical

    laboratory, diagnostic setting.


Current testing of blood donations for antibodies to hiv and hcv contd l.jpg
Current Testing of Blood Donations for Antibodies to HIV and HCV, contd.

EIA Screening Test

Non-reactive (NR)

Initially reactive (IR)

Use unit, retain donor

Test sample in duplicate

Both duplicates NR

Next slide

Use unit, retain donor


Current testing of blood donations for antibodies to hiv and hcv contd5 l.jpg
Current Testing of Blood Donations for Antibodies to HIV and HCV, contd.

Test sample in duplicate

Both duplicates NR

Use unit, retain donor

Either or both duplicates test reactive

Unit is repeatedly reactive (RR),

Unit not used, defer donor

Donor evaluated by more testing using

supplemental assays


Current testing of blood donations for antibodies to hiv and hcv contd6 l.jpg
Current Testing of Blood Donations for Antibodies to HIV and HCV, contd.

  • Supplemental testing on EIA

    screening test RRs

    - for anti-HCV use RIBA

    - for anti-HIV use Western Blot

    or IFA followed by anti-HIV 2, if indeterminate results are obtained


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Supplemental Testing of HCV, contd. Donors/Donations

  • Each screening test reactive donation must be tested by a supplemental test if approved for such use, 21 CRF 610.40

  • Donors must be notified of deferral; an attempt must be made to obtain supplemental test results prior to donor notification, 21 CFR 630.6


Supplemental testing of donors donations contd l.jpg
Supplemental Testing of HCV, contd. Donors/Donations, contd.

  • Alternative donor testing algorithms, not using supplemental tests, would conflict with regulations

  • Confirmation by “orthogonal testing” (testing using a different technique) advantageous over statistical validation methods, e.g., 2nd EIA, high EIA s/co ratio


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Why Perform Supplemental Testing on Donors? HCV, contd.

  • 1) Providing deferred donors with accurate information about their disease status and deferral helps ensure a healthy donor population.

    - This impacts directly on blood safety

    in preventing communicable disease

    transmission.


Why perform supplemental testing on donors contd l.jpg
Why Perform Supplemental Testing on Donors? contd. HCV, contd.

  • 2) Information from supplemental testing can be used to evaluate donor for possible reentry into donor pool.

    - Requalification of donors contributes

    to donor availability


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Testing in Different Settings HCV, contd.

  • Donor Setting: selected, low risk population tested outside the health care environment

  • Medical Diagnostic Setting: higher risk populations, medical “index of suspicion,” doctor-patient relationship permits additional considerations

    -rapid HIV testing at point of care; inability to perform delayed confirmatory testing


Discussion objectives l.jpg
Discussion Objectives HCV, contd.

Discuss:

  • The scientific merit and public health benefit of supplemental testing in a blood donor setting.

  • Relative performance of supplemental

    testing strategies for HIV and HCV:

    - HIV: Western Blot, NAT, 2nd EIA

    - HCV: RIBA, NAT, high s/co in the

    screening EIA


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Questions for the Committee HCV, contd.

  • 1. Please comment on the relative performance of:

    (i) RIBA versus HCV NAT

    (ii) RIBA versus signal-to-cutoff

    ratio in the screening test for

    anti-HCV

    to confirm/validate a reactive screening test

    result in the blood donor testing setting.


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Questions for the Committee HCV, contd.

  • 2. Please comment on the relative performance of:

    (i) Western Blot versus HIV NAT

    (ii) Western Blot versus a second EIA for

    anti-HIV

    to confirm/validate a reactive screening test

    result in the blood donor testing setting.


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