Panel Testing

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Panel TestingPanel Testing



Wh at is AFB Microscopy Panel Testing?Wh at is AFB Microscopy Panel Testing?

Assessment of the testing capability of technicians for detecting, quantifying,interpreting and reporting AFB smear resultsaccording to WHO/ IUATLD guidelines using aset of (prepared) stained and un-stained sputumsmears



Panel test s h ould contain:Panel test s h ould contain:

Number and types of slides to reassure thatcorrect or incorrect results are not accidental

At least 10 slides provides a valid and fair test Represent a challenge in terms of difficulty

-some scanty and low-positive smearsUnstained smears evaluate staining techniqueTesting in the lab provides information stainpreparation and quality



U ses of Panel TestingU ses of Panel Testing

Assess current status of performance of laboratory staff

Quickly detect and assess problems associatedwith very poor performance

Evaluate competency of laboratory techniciansprior to and following training

Monitor performance of individuals in absence of a rechecking program

Supplement rechecking programs



Panel Testing: Issues to consider Panel Testing: Issues to consider

Technicians know they are being evaluatedTime allowed for technicians in laboratories tocomplete PT

Availability of microscopes while regular testingis in progress

Evaluation criteria for acceptable performancePlan for reporting feedback and implementcorrective action if needed

Mechanism to resolve discrepant results



Ex amples of Panel TestsEx amples of Panel Tests

1 slide graded 3+1 S lide graded 2+1 slide graded 1+2 slides graded

1-9 / 100 fields5 negative slides

1 slide graded 3+1 slide graded 2+2 slides graded 1+3 slides graded 1-9 /

100 fields3 negative slides

1 slide graded 2-3 +2 slides graded 1+3 slides graded 1-9 /

100 fields

4 negative slides

1 slide graded 2-3 +2 slides graded 1+4 slides graded 1-9

/ 100 fields

3 negative slides



G etting startedG etting started



Implementation of Panel TestingImplementation of Panel Testing

Determine the # AFB technicians in eachLaboratory for PT slide preparation

Communication with Public Health Directorsregarding EQ A activitiesPreparation of schedule for Panel Testing ineach location



C entral Laboratory Use Only:Test S lide set # ______________________ Date S ent:__________________________ Date results received:_________________

R eference Laboratory Only

S lide N umber R esultEx pected

R esultE rror Type Points

Appendi x C.3

PT Form 3: Panel Testing Recording and Feedback Form

Peripheral Laboratory:_____________________________________________________ Date PT received by your laboratory_________________________ (DD/ MM /YY)Date PT results returned to C entral Laboratory _________________( DD/ MM /YY)N ame of technician reading test smears: ___________________________________________ N ote: If more than one technician performs AFB microscopy in the laboratory, each technician should read all 10 smears and record their resultson a separate form. Technicians should not discuss results or share forms until all results have been sent back to the central laboratory. Formsfor all technicians should be sent to the central laboratory for evaluation.

Feedback

Total Points Pass/Fail:

HFP HF N LFN LFP QE

R ecommended Action:



Prepared Panel SetsPrepared Panel Sets

Provide unstained and stained smearsProvide uniformity of the test for technicians

Provide known quantification of AFBBetter than patient smears



Manufacturing Smears for PTManufacturing Smears for PT

Should be made in the N ational TB R eference Laboratory-requires a safety hood, centrifuge, vorte x and water

bath Quantifications made from known positive sputa

Homogenization of sputa with N a OH and formaldehyde- often requires N acetyl-l- cysteine to avoid clumping

Concentration and centrifugation to sediment AFB

Dilute to desired AFB concentration with negative sputumdilution

Make 50-100 smears for each dilution or quantificationFix smears but do not stain



V alidation of Panel Test SlidesV alidation of Panel Test Slides

Stain 6 slides from each batch to be e xaminedindependently by different technicians

Calculate standard deviation and average resultsThe average minus 2 std should be > 0 to beacceptableOtherwise the lot is too inconsistent and must be

discarded Keep accurate records of confirmed batches,including dates and detailed results of thevalidation process



Performing a Panel Test RoundPerforming a Panel Test RoundUsually done once per year

Responsibility of the NR L-preparation of slides toanalysis and feedbackUse a standardized PT reporting formLetter and basic instructions regarding staining, timeallowed

Stress that individual technician must e x amine andreport separatelyInform that there are no incentives or punitive actions

as a result of the ex

ercisePanels can be sent but care must be taken to avoidbreakage



Analysis of PT ResultsAnalysis of PT Results

A scoring system is developed prior to testDistinguish major and minor errors- false positive/negative related to 1+, 2+ or 3+

errors Quantification errors (at least a 2 grade

difference and errors in the 1-9 AFB areconsidered minor

Determine successful scoreDetermine plan of action for poor performances



Types and Classification of E rrorsTypes and Classification of E rrors

Result of ControllerResult beingrechecked Negative 1-9

AFB/100 f 1+ 2+ 3+

Negative correct LFN HFN HFN HFN1-9 AFB/100

f

LFP Correct Correct QE QE

1+ HFP Correct Correct Correct QE2+ HFP QE Correct Correct Correct3+ HFP QE QE Correct correct

Correct: No errorsQE Quantification error Minor errorLFN Low False Negative Minor errorLFP Low False Positive Minor errorHFN High False Negative Major errorHFP High False Positive Major error



Ex ample of PT ScoringEx ample of PT Scoring

Set of 10 slides, each slide is worth 10 points,total possible score = 100 ± HFP and HF N scores 0 ± LFP, LF N and QE scores 5 ± QE =2 ± Passing score = 80 ± 90 (determined by N TP)



PTPT± ±Interpretation and FeedbackInterpretation and Feedback

False positive and negative errors should beconsidered separatelyInvestigate reasons for poor performancePoor microscope; poor stains; poor technique;recognition of AFB?Poor performance often requires visit to

laboratory Reports to TB program coordinator should

provide appropriate background information andrecommendations and not simply scores



Feedback to Laboratories on PT resultsFeedback to Laboratories on PT results

Include individual and aggregate test resultsInclude criteria for acceptable performance

Recommend that laboratories investigatesources of error

Same smear error may represent a problem withsampleInvestigate poor performance

Assure that poor performance is not due tosample problems in R eference laboratory



Panel TestingPanel Testing- - Ot h er important pointsOt h er important points

Use of lab microscopes- and panel testing Correlate onsite evaluations with panel testing

Use of panel testing with AFB microscopytraining

Pre-testing to individualize specific trainingneedsPost test results confirms competency after

training Administration during on-site visits may bemost cost-effective

Corrective action associated with performanceproblems may be easily assessed andfacilitated





AcknowledgementsAcknowledgements

International EQ A Workgroup APHL C DC IUATLD KNCV R IT WHOM e x ican C olleagues (InD RE )

Zambian C olleagues ( C DL)

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Panel Testing