Title: Development of Rapid HIV Tests for use in diagnostic settings
1Supplemental Testing of Donors for HIV and HCV
September 18, 2003 BPAC Meeting Robin Biswas,
M.D. Indira Hewlett, Ph.D. FDA/CBER/OBRR/DETTD
2Supplemental 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
-
3Reason 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.
-
-
4Current Testing of Blood Donations for Antibodies
to HIV and HCV, contd.
Non-reactive (NR)
Initially reactive (IR)
Use unit, retain donor
Test sample in duplicate
Both duplicates NR
Next slide
Use unit, retain donor
5Current 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
6Current 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
7Supplemental 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
8Supplemental 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
9Why 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.
10Why 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
11Testing 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
12Discussion 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
-
-
13Questions 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.
14Questions 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.