Transcript Validating Supplemental Testing to Confirm Preliminary

Performance of Bio-Rad Genetic Systems
HIV-1/HIV-2 Plus O EIA Followed by
Multispot or OraQuick Advance in a Dual
Immunoassay HIV Testing Strategy
Laura Wesolowski, PhD*
S. Michele Owen, PhD
Debra Candal, BS
Susan Phillips, BS
Steve Ethridge, BS, MT (ASCP)
Duncan MacKellar (MA, MPH)
*Diagnostic Applications Team, Behavioral and Clinical Surveillance Branch,
Centers for Disease Control and Prevention
Objectives
– To assess the sensitivity and specificity of a dual
immunoassay testing strategy using Bio-Rad HIV1/HIV-2 Plus O EIA (A1) followed by Multispot HIV1/HIV-2 rapid test (A2) for HIV-1 diagnosis
– To describe the concordance of A2 test (Multispot)
when run in duplicate
– To assess the sensitivity of a dual immunoassay
testing strategy using Bio-Rad EIA (A1) and OraQuick
Advance (A2) rapid test for HIV-1 diagnosis
Background
• Lack of performance data for EIA followed by rapid test
• Concern about similarity of antigens in EIAs and rapid
tests on market
– may contribute to dual false positives
• Bio-Rad EIA
–
–
–
–
3rd generation EIA (detects IgG and IgM)
Serum or plasma
Sensitivity: 100% (99.84-100%)
Specificity: 99.89% (99.83-99.96%)
Background: Multispot
– Serum or plasma
– Sensitivity
• Serum and plasma
100% (99.94-100%)
– Specificity
• Serum
99.93% (99.79-100%)
• Plasma
99.91% (99.77-100%)
Background: OraQuick Advance
-
Whole blood or plasma
Sensitivity
• Whole blood
99.6% (98.5 - 99.9)
• Plasma
99.6% (98.9-99.9)
-
Specificity
• Whole blood
100% (99.7-100%)
• Plasma
99.9% (99.6-99.9%)
Methods: HIV-1 uninfected specimens
• HIV-uninfected specimens: plasma samples from
uninfected blood donors
– EIA negative (Abbott HIV AB HIV-1/HIV-2 (rDNA))
– Pooled HIV-1 PCR-negative (Roche Ampliscreen)
• Uninfected specimens tested with Bio-Rad EIA and
Multispot (in duplicate) at CDC. Not tested with
OraQuick yet.
Methods: HIV-1 infected specimens
• HIV-1 infected specimens: Serum Western blot positive specimens
from CDC’s “Validating Supplemental Testing to Confirm Preliminary
Positive Rapid HIV Tests”
• CDC IRB Approved: Feb. 2006
• Enrollment began March to June 2006
– Enrollees from 6 study sites
• AIDS Research Consortium of Atlanta, GA
• Denver Metro Health (STD) clinic
• Philadelphia FIGHT, Jonathan Lax HIV Clinic
• Howard Brown Health Center, Chicago, Gay & Lesbian
Health Clinic
• Louisville Hospital, Louisville, KY, WINGS STD Clinic
• University of MD Baltimore, Evelyn Jordan Center (HIV
Clinic)
– Reference laboratory: University of MD
Methods: HIV-1 infected specimens
– Inclusion criteria:
• Previously diagnosed with HIV infection
• No antiretrovirals within 3 months
• Not pregnant
• 18 - 55 years
• Understand English
– Infected specimens tested at UMD (Bio-Rad EIA) and CDC
(Multispot in duplicate)
– OraQuick Advance conducted at study site using whole blood
(not in duplicate)
Methods: Outcomes
• Specificity and sensitivity for Bio-Rad EIA (A1) followed
by Multispot (A2) individually and together in dual test
strategy
• Concordance of Multispot results run in duplicate
• Sensitivity for Bio-Rad EIA (A1) followed by OraQuick
Advance (A2) individually and together in dual test
strategy
Specificity=True negative/(true negative + false positive)
Sensitivity=True positive/(true positive + false negative)
Results: Specificity Bio-Rad EIA and
Multispot
• Among 302 HIV-uninfected persons:
– 4 false positive on Bio-Rad EIA
(specificity=298/302=98.7%)
– 7 false positive on Multispot
(specificity=295/302=97.7%)
– 0 false positive on both Bio-Rad EIA and
Multispot
Strategy 3. HIV-1/2 dual immunoassay for 4 initially false positive on
Bio-Rad EIA (truly uninfected)
A1 BioRad EIA
A1 (+)
A1 (-)
Negative for HIV-1 and
HIV-2 antibodies†
A1 (- -)
A2 Multispot in duplicate
A2 (- -)
Repeat A1
in duplicate
A1 (++ or + -)
A2 (++ or + -)
Presumptive positive for HIV-1 or
HIV-2 antibodies; requires medical
follow-up for further evaluation and
testing
Inconclusive for HIV antibodies;
request plasma redraw for NAAT†
Requires medical follow-up for further
evaluation and testing
HIV-2 Testing; Strategy 5, if applicable
*Must be a different EIA, CIA, or non-waived rapid test depending on laboratory setting (for A2 only)
† If window period infection is suspected based on risk assessment or discordant testing, refer to Acute HIV Infection
Testing, Strategy 4
Results: Specificity Bio-Rad EIA and
Multispot
• Strategy specificity excluding those with
inconclusive results=300/300=100%
• 2 uninfected persons eventually get correct
results, but in the interim will be told that their
results are inconclusive and have to wait for
correct results after NAAT testing
Results: Sensitivity Bio-Rad EIA and
Multispot
• Among 1065 HIV-infected persons:
– 0 false negative on Bio-Rad EIA
(sensitivity=1065/1065=100%)
– 1 false negative on Multispot
(sensitivity=1064/1065=99.9%)
– 0 false negative on both Bio-Rad EIA and Multispot
Strategy 3. HIV-1/2 dual immunoassay for 1 person false negative on Multispot
(truly infected)
A1 BioRad EIA
A1 (+)
A1 (-)
Negative for HIV-1 and
HIV-2 antibodies†
A1 (- -)
A2 Multispot in duplicate
A2 (- -)
Repeat A1
in duplicate
A1 (++ or + -)
A2 (++ or + -)
Presumptive positive for HIV-1 or
HIV-2 antibodies; requires medical
follow-up for further evaluation and
testing
Inconclusive for HIV antibodies;
request plasma redraw for NAAT†
Requires medical follow-up for further
evaluation and testing
HIV-2 Testing; Strategy 5, if applicable
*Must be a different EIA, CIA, or non-waived rapid test depending on laboratory setting (for A2 only)
† If window period infection is suspected based on risk assessment or discordant testing, refer to Acute HIV Infection
Testing, Strategy 4
Results: Sensitivity Bio-Rad EIA and
Multispot
• Strategy sensitivity excluding those with
inconclusive results=1064/1064=100%
• 1 HIV-infected person likely have inconclusive
results and would have to await NAAT results
Results: Multispot duplicates
• All Multispots same result on duplicate as when initially
run (i.e. non-reactive on both test runs or reactive on
both test runs)
– Testing in duplicate did not provide any additional information on
infection status for those with false positive or false negative
results
Results: Sensitivity Bio-Rad EIA and
OraQuick
• Among 1065 HIV-infected persons:
– 0 false negative on Bio-Rad EIA
(sensitivity=1065/1065=100%)
– 0 false negative on OraQuick (whole blood)
(sensitivity=1065/1065=100%)
– 0 false negative on both Bio-Rad EIA and OraQuick
– Strategy sensitivity=1065/1065=100%
Conclusions
• Dual test strategy using Bio-Rad EIA and Multispot has
high sensitivity and specificity. However, some persons
would receive inconclusive results and require additional
testing to get correct result.
• Conducting the secondary screening test in duplicate
does not appear to be beneficial.
• Dual test strategy using Bio-Rad EIA and OraQuick has
high sensitivity, though specificity should be evaluated.
Next steps
• Continue testing samples with Bio-Rad EIA, Multispot
and OraQuick
• Obtain challenge specimens (false EIA positive, NAAT
negative) to challenge dual immunoassay strategy
Acknowledgements
• PIs & staff from 6 study sites
• University of MD Laboratory of Viral
Diagnostics
• MDC Associates, Joanne Lebrun
• CDC
– Bernard Branson
– Maxia Dong
– Tim Granade
– Dollene Hemmerlein
– Sheryl Lyss