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Development of Rapid HIV Tests for use in diagnostic settings

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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 ... – PowerPoint PPT presentation

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Title: Development of Rapid HIV Tests for use in diagnostic settings


1
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
2
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 TEST RESULT
  • 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

3
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.

4
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
5
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
6
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

7
Supplemental Testing of 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

8
Supplemental Testing of 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

9
Why Perform Supplemental Testing on Donors?
  • 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.

10
Why Perform Supplemental Testing on Donors? 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

11
Testing in Different Settings
  • 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

12
Discussion Objectives
  • 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

13
Questions for the Committee
  • 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.

14
Questions for the Committee
  • 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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