Can a second rapid HIV test discriminate false positives as effectively as a Western Blot? The NJ Experience - PowerPoint PPT Presentation

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Can a second rapid HIV test discriminate false positives as effectively as a Western Blot? The NJ Experience

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Title: Slide 1 Author: cadoff Last modified by: Anterio Cunningham Created Date: 6/9/2005 12:54:17 PM Document presentation format: On-screen Show Company – PowerPoint PPT presentation

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Title: Can a second rapid HIV test discriminate false positives as effectively as a Western Blot? The NJ Experience


1
Can a second rapid HIV testdiscriminate false
positives as effectively as a Western Blot? The
NJ Experience
Cadoff EM, Cadoff RA, Salaru G, Paul SM, Martin EG
  • Evan M. Cadoff, MD
  • Robert Wood Johnson Medical School
  • New Brunswick, NJ

2
NJHIV Rapid Testing Program
  • Under direction of RWJMS
  • OraQuick started November 1, 2003
  • Oversees about 2/3 of NJ CTS HIV testing
  • Confirmatory testing at PHEL in Trenton
  • NJHIV oversees followup of all discordant
  • NJHIV does not evaluate linkage to care

3
Preliminary Positive Followup
  • 7.1 refused blood draw for confirmation
  • 25.8 of those drawn did not return for results
  • 70.1 of confirmed positives got their results
    and post-test counseling
  • Rapid confirmation could improve effectiveness of
    prevention and referral/entry to care and
    treatment services

4
Data Needs for Proposed Testing Strategies
  1. Are there false negative screening tests?
  2. Can true positive screening tests be confirmed by
    a second rapid test, rather than WB/IFA/NAT?
  3. Can false positive screening tests (ie
    discordants) be detected by a second rapid test,
    rather than waiting for WB/IFA/NAT?
  4. Impact on linkage to care?
  5. How well can inconclusive second-round test
    results (eg, WB vs a second rapid test) be
    resolved?

5
Two NJHIV Datasets
  • Confirm true positives
  • Evaluate confirmed false positives
  • Resolve discordants and indeterminate
    confirmatory test results

6
Nov 2003 April 2005 data
  • Rapid testing by blood only using OraQuick
  • Western Blot specimens sent to PHEL
  • All avialable WB specimens evaluated by
  • Repeat OraQuick on blood
  • Trinity Uni-Gold
  • MedMira Reveal
  • BioRad Multispot
  • Followup of clients with discordant results

7
Nov 2003 April 2005 data
  • 15,923 OraQuick tests statewide
  • 363 preliminary postive samples to state lab for
    Western Blot
  • 355 Western Blot positive confirmed by other
    rapids
  • 8 Western Blot negative discordants
  • all repeat OraQuick positive
  • one reactive Multispot by one reader
  • others all negative
  • 6 preliminary positive is false positive
  • 25 with no clinical followup

Strategy 1, Data Need 3
8
Discordant followup
  • Four visits
  • Rapid test. If prelim pos, draw blood and send
    to Trenton for Western Blot.
  • Return in a week, and get discordant confirmatory
    test result.
  • Return at a month to have more blood drawn
    (repeat antibody and NAAT).
  • Come back a week later for definitive result.

9
Discordant followup
10
Revised discordant followup
  • Three Visits
  • If rapid test is reactive, draw Western Blot.
  • Return in a week. Get discordant confirmatory
    test result and draw NAAT.
  • Third visit for NAAT result.
  • or
  • Two Visits
  • If rapid test is reactive, draw both Western Blot
    and NAAT.
  • NAAT is run if WB is discordant, and both results
    are available at second visit.

11
Revised discordant followup
  • Three Visits
  • If rapid test is reactive, draw Western Blot.
  • Return in a week. Get discordant confirmatory
    test result and draw NAAT.
  • Third visit for NAAT result.
  • or
  • Two Visits
  • If rapid test is reactive, draw both Western Blot
    and NAAT.
  • NAAT is run if WB is discordant, and both results
    are available at second visit.
  • or
  • One visit with rapid confirmation would be better!

12
Jan 2006 Oct 2007 data
  • Retained specimens from followup testing for
    discordant Western Blot results.
  • Cannot confirm true positives.
  • Can evaluate discordants and indeterminates (if
    they had followup).

13
Jan 2006 Oct 2007 data
  • Samples are not from the same time as screening
    OraQuick.
  • Used CLIA-waived tests
  • Repeat OraQuick on blood
  • Trinity Uni-Gold
  • Clearview StatPak

14
Jan 2006 Oct 2007 data
  • 108 false positive 72 without followup may be
    false positive Strategy 1, Data need 3 Strategy
    4, Data need 5a
  • No false positive strategy results Strategy
    4,Data need 1
  • No false negative A2 or A3 Strategy 4, Data need
    4, 5b

15
Jan 2006 Oct 2007 data
  • No false positive strategy results Strategy 3,
    Data need 1
  • 1 false positive A1-blood result Strategy 3,
    Data need 4a,5
  • 91 false positive A1-oral results Strategy 3,
    Data need 5
  • No false negative A2 results Strategy 3, Data
    need 4b

16
Jan 2006 Oct 2007 data
No false positive strategy results Strategy 2,
Data need 1 17 Inconclusive results with false
positive A1 Strategy 2, Data need 4
17
Data Needs for Proposed Testing Strategies
  • All followups on negative Western Blot were NAAT
    negative (OraQuick false positive).
  • All were "second rapid" negative.
  • Oral OraQuick followed by blood OraQuick
  • 3 tested at CTS site on False Positives
  • 2 blood negative 1 blood positive
  • 56 tested on followup blood specimen
  • all blood negative
  • OraQuick blood discordant
  • 11 tested on followup blood specimen
  • 7 negative
  • 4 repeat positive

18
Observations
  • Indeterminate Western Blot
  • 12 total
  • 4 no followup 3 QNS
  • 3 NAAT negative were "second rapid" negative
  • 2 NAAT positive were "second rapid" positive

19
Rapid Confirmation Is Needed
  • Rapid confirmation of preliminary positive
    results is necessary
  • 30-40 without followup would have benefited from
    rapid confirmatory testing.

20
Rapid Confirmation Works
  • All 355 true positives confirmed using a second
    rapid test (from a pool of about 16,000 clients
    tested)
  • All 65 false positives with followup available
    were negative using a second rapid test (from a
    pool of about 120,000 clients tested)
  • Indeterminate Western Blots were resolved by a
    second rapid

21
Conclusions
  • Rapid confirmation of preliminary positive
    results is necessary.
  • Rapid confirmation of preliminary positive
    results works at least as well as Western Blot
    testing.

22
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