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Kelley Bemis. CDC/CSTE Applied Epidemiology Fellowship STD Control Program Connecticut Department of Public Health k [email protected]. Use of automated testing in syphilis diagnosis and its impact on surveillance – Connecticut , 2010. Background. - PowerPoint PPT Presentation
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Kelley Bemis
Use of automated testing in syphilis diagnosis and its impact on surveillance –
Connecticut, 2010
CDC/CSTE Applied Epidemiology FellowshipSTD Control Program
Connecticut Department of Public [email protected]
Background
Graph: Together We Can SEE: The National Plan to Eliminate Syphilis, CDC, 2006
National Plan to Eliminate Syphilis implemented
Primary and Secondary Syphilis Cases - 2002 - 2010
2002 2003 2004 2005 2006 2007 2008 2009 20100.00
0.50
1.00
1.50
2.00
2.50
3.00
3.50
4.00
4.50
5.00
Connecticut Incidence 2010 Goal for National IncidenceNational Incidence
Years
Cru
de In
cide
nce
Per 1
00,0
00
+177% from 2008 to 2010
National elimination plan reframed
Crucial for syphilis elimination• Identify infectious patients (laboratory confirmed)
for partner notification• Identify outbreaks and target interventions
Mainly laboratory reporting• Labs must report positive tests in 48 hours• Mail reports to DPH
Syphilis Surveillance
Understanding laboratory testing is necessary for accurate surveillance
Usually two serologic tests Non-specific test
• e.g. rapid plasma reagin test (RPR), Venereal Disease Research Laboratory test (VDRL)
• Detects antibodies against host lipoidal antigens• Indicates active infection• Inexpensive, simple, manual
Specific test• e.g. T. pallidum particle agglutination (TPPA),
fluorescent treponemal antibody absorption assay (FTA-ABS)
• Detects antibodies against treponemal antigens• Indicates infection, past or present
Syphilis Diagnosis
Traditional Screening Algorithm
Syphilis unlikely
+ -
Syphilis unlikelySyphilis
+ -
Non-specific test
(RPR or VDRL)
Specific test (TPPA or FTA-
ABS)
One positive doesn’t confirm infection• Surveillance must monitor for two positives
Non-specific titers vary with age and stage of infection• Surveillance must consider past test results and
likelihood of infectiousness
Challenge for Surveillance #1
Positive test ≠ Active infection
Challenge for Surveillance #2
Photo credit: Reverse Sequence Syphilis Screening Webinar, CDC, 2011
Treponemal EIAs and CIAs gaining popularity
More expensive but less manual labor needed
Still can’t distinguish between active and past infection
A shift in testing paradigm: Automated treponemal tests for screening
Reverse Sequence Screening Algorithm
+Syphilis
-Specific test
(TPPA)
Syphilis (old or new)
+
EIA or CIA
Non-specific test
(RPR or VDRL)
+
Syphilis unlikely
-
Syphilis unlikely (or do another specific test)
-
Not identified with traditional algorithm
1. False positive EIA or CIA
2. Previously treated syphilis
3. Early primary syphilis
Challenge for Surveillance #2
Increased testing volume
New questions for surveillance• How should EIAs and CIAs be reported?• Should discordant results be investigated?
Increased DPH workload
Objectives
Determine type and volume of syphilis testing performed by Connecticut laboratories
Determine if current surveillance procedures adequately monitors reported tests for infectious cases
To conduct a laboratory-focused evaluation of syphilis surveillance in Connecticut
Methods, Part 1Laboratory Survey Web survey emailed to all hospital and
commercial labs in Connecticut (n=30)• Number of tests performed in 2010• Testing algorithm• Reporting practices
Responses analyzed with descriptive statistics
Methods, Part 2Laboratory Audit Requested records from two commercial
laboratories• All patients with a positive test in 2010
Compared against records in state’s surveillance database
Investigated selection of tests missing from state’s database
Laboratory Survey Results
30 of 30 (100%) labs completed the survey
28 of 30 (93%) perform syphilis testing
Over 196,700 screening tests performed in 2010
Uptake of Automated Tests
Using automated tests
Using manual tests
0
5
10
15
20
25
30
4
24
Num
ber o
f Lab
orat
orie
s
Referring Samples is Common
Refers samples for confirmatory test-
ing
Does not refer samples
0
2
4
6
8
10
12
14
16
15 9
4
Labs Using Automated TestsLabs Using Manual Tests
Num
ber o
f Lab
orat
orie
s
Reporting Results
Reports both test results*
Does not report both test results
0
2
4
6
8
10
12
14
16
3 1
11 13
Labs Using Automated Tests Labs Using Manual Tests
Num
ber o
f lab
orat
orie
s
Laboratory Audit Results
Lab B Screens with an EIA
Confirms all +’s with RPR and TPPA
RPR and TPPA reported
372 (29%) of 1299 positive reportable tests were not in the state’s database
Lab A Screens with a VDRL
Confirms with a FTA-ABS
RPR and FTA-ABS reported
693 (56%) of 1241 positive reportable tests were not in the state’s database
Laboratory Audit Results
Lab B• All patients with both RPR
and TPPA missing (n=13)
Lab A• Random sample (n=35
patients) representing different months, tests, and titers
Small sample of missing tests investigated from both labs
Most patients did not merit field investigation
We concluded that entry into state database is not consistent for these tests
Conclusions Uptake of automated tests is moderate, but
increasing
Automated testing algorithms are variable
Referring specimens is common
Labs do not always report both types of tests used for diagnosis
Standard protocols for entering lab tests do not exist or are not enforced
Recommendations
Create protocols for entering tests into the surveillance database
• All non-specific tests are entered• Treponemal results may be entered only once• Negative tests will be entered if reported
Recommendations
Establish provisional procedures for monitoring EIA/CIA’s and discordant results
• EIA/CIA’s do not need to be reported unless a manual treponemal test was not performed
• Discordant results will not be investigated
Recommendations
Offer training on interpretation of EIA/CIA’s• Internal meetings with DPH Disease
Intervention Specialists (DIS)• Newsletters to local health epidemiologists
and clinicians
Recommendations
Offer training on reporting requirements to laboratories
• Newsletter to Laboratory Response Network
Acknowledgments
Virginia Kristie, MT ASCP
Mark Lobato, MD
Lynn Sosa, MD
Connecticut laboratories
This study was supported in part by an appointment to the Applied Epidemiology Fellowship Program administered by the Council of State and Territorial Epidemiologists (CSTE) and funded by the Centers for Disease Control and Prevention (CDC) Cooperative Agreement Number 5U38HM000414.
Extra Slides
Reporting of Referral Samples
From the OLC-15 Reporting Form:
From the Public Health Code:
Test Sensitivity and Specificity
Credit: Seña, A.C., White, B.L. & Sparling, P.F. Novel Treponema pallidum Serologic Tests: A Paradigm Shift in Syphilis Screening for the 21st Century. CID 51, 700-708 (2010).
EIA/CIA Algorithms in Connecticut
EIA
EIA
CIA
CIA
RPR
TPPA
+&
+
+
+ RPR
RPR-
TPPA
RPR
&EIA x2
-TPPA
Sero-reactivity in Syphilis Tests
Credit: Peeling et al. / Bulletin of the World Health Organization / 2004 / Vol. 82 / No. 6 via CDC Reverse Sequence Screening Webinar