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CDC External Quality Assessment/ Proficiency
Testing: An experience in 43+ countries
Shon Nguyen, B.S, MPH
Viral Load and Early Infant Diagnosis Team
International Laboratory Branch Division of Global HIV/AIDS
CGH/Centers for Disease Control and Prevention
Content Overview
• Quality Assurance
• Proficiency Testing Program
• CDC PT program for EID
• CDC PT program for HIV-1 VL
Quality Assurance (QA)
Safety Quality Control (QC)
External Quality Assessment (EQA)
Site Visits Re-testing Proficiency Testing (PT)
Record Keeping Other
Quality Assurance Activities
External Quality Assessment Activities
Proficiency Testing
Testing of blinded samples at
regular interval by all participants
Retesting
Random selection of clinical samples collected by testing sites and sent to NRL for verification
Site Visits
A team of supervisors assesses site and provides feedback report for improvement
All Pos and 10% Neg 5 Samples 2 or 3x/yr Supervisory Visit
Prepare samples
Analyze results
Prepare report Evaluate
Report results
Examine samples
www.gov.uk
Provider Participants
Proficiency Testing Process
¨ Provide early warning for systematic problem
¨ Increase confidence in the quality of a laboratory’s performance
¨ As a quality indicator for stakeholders at various levels
¨ Quality evaluation and improvement of the testing process
¨ Demonstrate employee competency
¨ To monitor trends in results
Proficiency Testing Benefits
Sample Type Characteristics for PT Liquid (Serum/plasma) • Requires cold chain transport
• Risks of spills • Expensive • Biohazard
Dried blood spot (DBS) • Transported at room temperature • Inexpensive • HIV-1 Qual testing for Early Infant
Diagnosis (EID)
Dried tube specimen (DTS)
• Transported at room temperature • Inexpensive • HIV-1 RNA Viral Load testing [polymerase
chain reaction (PCR) based assays]
Proficiency Testing Sample Types
¨ Voluntary programs
¨ Offered free of charge
¨ Laboratories actively performing EID/VL testing
¨ Each laboratory may enroll more than one testing platform
¨ Two or three testing cycles per year
CDC PT Programs for EID AND VL
• Each PT package consists of • 1 sheet of PT Panel (duplicate set of 5 DBS) • 1 sheet of Positive Control (10 DBS) • 1 sheet of Negative Control (10 DBS) • Instructions and Process checklist form
EID PT Panel Package
0
10
20
30
40
50
60
0
20
40
60
80
100
120
140
160
180 20
06-2
20
06-3
20
07-1
20
07-2
20
07-3
20
08-1
20
08-2
20
08-3
20
09-1
20
09-2
20
09-3
20
10-1
20
10-2
20
10-3
20
11-1
20
11-2
20
11-3
20
12-1
20
12-2
20
12-3
20
13-1
20
13-2
20
14-1
20
14-2
20
15-I
Num
ber o
f cou
ntrie
s
Num
ber o
f par
ticip
ants
Test Cycle
CADU NHLS CDC Countries
EID PT Participants
CDC NHLS CADUPT
Event Countries Laboratories Countries Laboratories Countries Laboratories
2013-1 39 130 2013-2 37 134 4 21 2014-1 42 103 4 22 2014-2 43 125 4 22 9 202015-I 32 86 10 42 9 21
0 10 20 30 40 50 60
0
50
100
150
200
2006
-2
2006
-3
2007
-1
2007
-2
2007
-3
2008
-1
2008
-2
2008
-3
2009
-1
2009
-2
2009
-3
2010
-1
2010
-2
2010
-3
2011
-1
2011
-2
2011
-3
2012
-1
2012
-2
2012
-3
2013
-1
2013
-2
2014
-1
2014
-2
2015
-I N
umbe
r of c
ount
ries
Num
ber o
f par
ticip
ants
Test Cycle
CADU NHLS CDC Countries
EID PT Participants
• Each PT package consists of • Two identical sets of 5 DTS member PT panel • One tube of 13 mL of PBS • Instructions and processing checklist form
VL PT Panel Package
¨ Testing results are compared intra-platform ¨ Grading of results is completed if 6 or more results are
reported for a given test platform
¨ Results grading: limits of acceptability = mean +/- 3 SD
¨ Results summary report included both graded and non-graded results
¨ All participants receive results report but not all participants receive a graded result
VL PT Results Analysis
0
20
40
60
80
100
120
140
160
Countries Participants
Test Cycle
Num
ber
Participants and Countries in CDC VL PT Program
0 10 20 30 40 50 60 70 80 90 100
0
20
40
60
80
100
120
140
160
180
Number of participants unreported results Number of participants reported results % of reported participants with a passing score
Test Cycle
Num
ber o
f par
ticip
ants
% o
f par
ticip
ants
with
a p
assi
ng s
core
VL PT Participants and Results
Mea
n Pr
ofic
ienc
y Sc
ore
Number of Cycles Participated
R² = 0.23072
0
20
40
60
80
100
0 1 2 3 4 5 6 7 8 9 10
n= 23 28 18 17 12 12 13 10 14 8
n 1 5 10 15
Improve Performance of Laboratories Participated in CDC VL PT
§ Majority of participants score 100%
§ HIV-1 VL PT program using virus stock for DTS provides an excellent quality assurance tool
§ Participants’ Challenges in Meeting Result TAT (30 days) Ø No reagents Ø Expired kits Ø Instrument in need of repair Ø Long delay in clearing customs
Findings
Ø Improve results TAT and thereby increase results reporting and grading
Ø Analysis of PT data to evaluate the HIV programs and provide country guidance
Ø Website for CDC PT programs (ePT)
Ø Evaluate DBS for HIV-1 VL PT for POCT
Ø Transfer PT technology to the field
Future Directions
Field participants Academic Affairs, Research and
Quality Assurance, National Health Laboratory Service (NHLS)
South Africa
Bacteriology and Virology laboratory, University Cheikh Anta
Diop, (CADU) Dakar, Senegal
All PT participants who contributed
their data included in this report
CDC-HQ/ILB John N. Nkengasong, PhD
Guoqing Zhang, PhD Rachel S. Beard, PhD
Karidia Diallo, PhD Katrina Sleeman, PhD
Mackenzie Hurlston, MSPH Stephen Jadczak, BS
Artur Ramos, PhD Joy Chang, PhD
Chunfu Yang, PhD Vedapuri Shanmugam, PhD
Dennis Ellenberger, PhD Carole Moore, MLS
John Nahabedian, BS Debrah Boeras, PhD Albert Garcia, MPH
Shambavi Subarao, PhD Chin-Yin Ou, PhD
Christopher Rasberry, MS
Acknowledgements
3. Dry overnight at room temperature
2. Deliver 100 µL per spot
1. whole blood spiked with known number of 8E5 cells
5. Perform validation according to the assay protocol
4. Store in a bag with desiccants and humidity indicator card
3. Dry overnight at room
temperature
2. Deliver 20 µL into each tube
1. Working solution: add virus stock and green dye to PBS
For validation: Add 1.1 mL of PBS
Vortex 10 sec Perform testing immediately or store at 2-8ºC for 24 hrs
or -15ºC or colder for up to 1 week
DTS Preparation and Validation 4. Cap and
store at 2-8oC or -15oC
or colder
5 DTS specimens
HIV
-1 D
TS
VL
PT
VL2
012-
B1
HIV
-1 D
TS
VL
PT
VL2
012-
B1
HIV
-1 D
TS
VL
PT
VL2
012-
B1
HIV
-1 D
TS
VL
PT
VL2
012-
B1
HIV
-1 D
TS
VL
PT
VL2
012-
B1 PBS
buffer (1x)
One vial of PBS
Open one tube at a time, add 1.1 mL of PBS, Cap tube, vortex 10 sec.
Perform testing immediately or store 2-8oC for 24 hrs or -15oC or
colder for up to one week
DTS Testing
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