Transcript Carevent - 2012 HIV Diagnostics Conference

CDC HIV Diagnostics Conference
December 5-7, 2007
Sensitivity of OraQuick and Early Generation
Enzyme Immunoassay (EIA) within a Pooled HIV
Nucleic Acid Amplification Testing (HIV NAAT)
Program
J Stekler1,2, PD Swenson2, RW Coombs1,
J Dragavon1, RW Wood1,2, MR Golden1,2
From the 1University of Washington, Seattle, WA and
2Public Health - Seattle & King County (PHSKC), WA
Objective
●To describe the sensitivity of different HIV antibody
tests within an HIV NAAT program
● To understand that HIV test sensitivity may vary in
populations with different rates of HIV acquisition and
testing intervals
Background
● 9/2003: pooled NAAT testing began
● Targeted HIV NAAT: men who have sex with men (MSM)
prevalence = 16%
incidence = 2.7 per 100 person-years
● Sites:
rapid Ab testing: CBO, bathhouses, or high-risk at STD
1) UAI w/ HIV-positive or unknown serostatus partner,
2) bacterial STD, or
3) methamphetamine/popper use in last year
standard Ab testing (EIA): mostly “low-risk” STD clients
Methods: HIV testing
● Rapid testing
OraQuick (Orasure Technologies, Inc)
fingerstick whole blood or oral fluids
● EIA
Vironostika HIV-1 Microelisa System (Organon Teknika Corp)
Genetic Systems rLAV EIA (Bio-Rad Laboratories)
● HIV NAAT: 30 person pools (manually combined)
9/03-1/05: Procleix HIV-1 Discriminatory Assay (Gen-Probe Inc)
Individual NAAT also performed
2/05-present: independently validated real-time RT-PCR assay
Individual NAAT when acute HIV suspected
Methods: Retrospective testing
● Serum stored for confirmatory testing and quality control
● First OraQuick-neg/EIA-pos tester identified in 11/05 by NAAT
● After 11/05, OraQuick-neg MSM tested by EIA before NAAT
to reduce time/costs for pooled HIV NAAT
to decrease time to receive HIV-positive results
Other retesting
3rd gen. EIA (HIVAB HIV-1/HIV-2 (rDNA) EIA, Abbott Laboratories)
Other rapid tests
Clearview HIV 1/2 StatPak (Inverness Medical Prof. Diagnostics)
Uni-Gold Recombigen HIV-1 Test (Trinity BioTech)
False negative EIA and OraQuick results:
Data Needs for Strategy #3-1
Standard testers (MSM)
Cumulative
# HIV-positive Cumulative
N= 7437
“Sensitivity”*
EIA
148 (2.0%)
148
93%
NAAT
10 (0.1%)
158
99%
Rapid testers (MSM)
N= 5460
# HIV-positive Cumulative
Cumulative
“Sensitivity”
OraQuick
123 (2.3%)
123
83%
EIA
10 (0.2%)
133
89%
NAAT
16 (0.3%)
149
100%
*False-positive HIV NAAT = 0, False-negative HIV NAAT = 1
Individual NAAT: no additional cases in first 16 months of program
False positive test results (EIA):
Data Needs for Strategy #3-2
EIA-positive and WB “indeterminate”
1) Multiple “faint” bands, known HIV-pos =
2) “Faint” gp 120/160 – later confirmed =
3) “Faint” p24, gp55, gp160 – confirmed =
4) p40, RNA negative =
5) p66, RNA negative =
6) gp160, RNA negative (vaccine study) =
7) p18, RNA negative, 3 month f/u negative =
Standard testers
N= 7437
EIA-positive
EIA-negative
HIV-positive
151
11
true positive
true positive
true positive
false positive
false positive
false positive
false positive
Sensitivity = 93.2%
HIV-negative
Specificity = 99.9%
4
PPV = 97.4%
7271
NPV = 99.8%
False positive test results (OraQuick):
Data Needs for Strategy #3-2
Unconfirmed OraQuick results
1) Refused blood draw (n=5)
2) Confirmatory test elsewhere =
3) Indeterminate WB (p18, p55, gp160) =
4) Indeterminate rapid test =
5) Negative EIA/NAAT =
Rapid testers
N= 5455
HIV-positive
OraQuick-positive
125
OraQuick-negative
26
true positive
true positive
false positive (n=2)
false positive
Sensitivity = 82.8%
HIV-negative
Specificity = 99.9%
3
PPV = 97.7%
NPV = 99.5%
5301
Results: retesting frozen sera from
MSM with acute HIV infection
# with acute HIV infection
HIV-positive on retesting
by 3rd generation EIA 3 of 11 (27%)
by OraQuick
0 of 6
Number and % with discordant Ab test results:
Data Needs for Strategy #3-3
Rapid testers
N= 5455
EIA-pos
EIA-neg
OraQuick-pos
125
3
OraQuick-neg
11
5317
HIV-infected
0/3 (0%) EIA-/OQ+
10/11 (90.9%) EIA+/OQ(vaccine study participant)
Results: OraQuick-negative/EIA-positive testers
EIA
1) Vironostika
2) Vironostika
3) rLAV EIA
4) rLAV EIA
5) rLAV EIA
6) rLAV EIA
7) rLAV EIA
8) rLAV EIA
9) rLAV EIA
10) rLAV EIA
S/CO
6.2
2.4
4.7
5.2
6.4
4.7
4.7
4.3
6.6
6.0
WB
p24, p51, gp160
p24, p55, gp160
p24, p55, gp160
p18, p24, p55, gp160
p24, p65, gp160
p24, faint gp160 (indet)
p24, gp160
p24, p55, gp160
p24, p55, gp120/160
p24, p32, gp41, p51, p55,
gp120/160
Results of rapid HIV antibody tests on frozen
sera from MSM with early HIV infection
Clearview
Clinical Cases
OraQuick-neg/EIA-pos Positive
(n=5)
EIA-pos/gp41-neg
(n=5)
EIA-pos/gp41-pos
(n=5)
OraQuick
Uni-Gold
Weak positive (2) Weak positive (2)
(5) Positive
(2) Positive
(3)
Strong positive (1)
Weak positive (2)
Positive
(4) Positive
(4) Positive
(3)
Strong positive (1) Strong positive (1)
Positive
(1)
Strong positive (4) Strong positive (5) Strong positive (5)
“weak positive”:
barely visible
“positive”:
visible
“strongly positive”: easily visible
(specimen test line < positive control)
(test line ≥ positive control but < external control)
(test line reactivity ≥ external control)
Results (incidence/time)
NAAT window period = 14 days
EIA window period = 35 days
Test “sensitivity” by test frequency
HIV Test Quarterly Semi-annually Annually
HIV Ab
72%
84%
91%
HIV NAAT
86%
93%
96%
Assumptions:
1) Timing of testing is uniform
2) Testing is independent of risk
Conclusions
1) No HIV test has a sensitivity of 100%. HIV NAAT will
appear to be more effective with less sensitive Ab tests.
2) OraQuick may be less sensitive than 1st or 2nd
generation EIAs in early HIV infection. Other rapid tests
did not clearly perform any differently on stored sera.
3) As testing increases, sensitivity decreases because
of a greater likelihood of testing during the “window
period”. It is relatively more important to use the most
sensitive tests in populations with frequent HIV testing
and high rates of HIV acquisition.
Acknowledgements
Clients and providers at the Gay City Health Project, PHSKC
STD Clinic, and other PHSKC testing sites.
Mentors
Ann Collier
Matt Golden
Funding: The HIV NAAT pilot study was partially supported by
GenProbe Incorporated from 9/03-2/05.
Grants:
NIH K23 AI-65243
UW CFAR: NIH AI-27757