Validation, Verification and Quality Control Thomas Novicki Ph.D. D(ABMM) Marshfield Clinic...

Validation, Verificationand Quality Control

Thomas Novicki Ph.D. D(ABMM)

Marshfield Clinic

Marshfield WI

Today’s Topics

1.Validation and Verification of ID and AST systems

2.Quality Control (QC) of Identification (ID) and Antimicrobial susceptibility test (AST) systems

(We will not be discussing proficiency testing due to time constraints)

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Disclosures I have nothing relevant to this

presentation to disclose

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VALIDATION AND VERIFICATION

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Validation and Verification Validation: Documenting in vitro

diagnostic device performance in your lab

Verification: An ongoing demonstration of the vendor’s performance claims using a variety of tools

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Validation and Verification(or is it Verification and Validation…?)

Note that some entities (e.g. CLSI, CLIA) reverse the definitions Initially Verify Then periodically Validate

The definitions used don’t matter, but their consistent use in your lab is important.

What does your accrediting body use?

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Who Guides Us? Vendors of commercial systems The Clinical and Laboratory Standards

Institute (CLSI) The Feds

CLIA – Clinical labs FDA – Instruments

Your accrediting body (COLA, CAP, JC)(Did I miss anything…?)

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Validation and Verification

The Centers for Medicare and Medicaid Services (CMS), (a part of the US Department of Health and

Human Services) regulates clinical laboratory testing through the Clinical Laboratory Improvements

Amendments (CLIA) that became effective in 2003.

(Recall that it all began in 1988)

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Validation

For FDA cleared and approved tests, the lab demonstrates performance claims by the device manufacturer, typically found in the product label (‘package insert’)

For lab-developed tests (LDTs), a more rigorous set of studies demonstrating performance is necessary

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Validation of LDTs Will not discuss further except to say that any

modification of an FDA IVD makes it an LDT

Be wary of modifying the more critical FDA-approved test (e.g. TB, HIV IVD devices )

Qualitative tests easier to modify than quantitative

Simple cleared tests (e.g. MRSA chromo-agars for additional anatomical sites) are reasonably modified

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iClick? 1 CLIA requires a lab to validate which of

the following for every new diagnostic test1. Accuracy

2. Precision

3. Reportable and Reference ranges

4. All of the above

5. 1 and 2

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iClick? 1 - Discussion CLIA specifies that the user of an FDA IVD device of

Moderate/High complexity will Validate accuracy, Precision, Reportable range, and Reference range

You must satisfactorily complete validation of the device before beginning its use.

You must document all validation study data and maintain it for at least 2 years after test retirement.

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Validation – AST Two methods for an unmodified FDA-

cleared instrumentA. Compare to a reference methodB. Compare to an existing system

Method B probably the best fit for most labs with an existing system For method A, see Cumitech 31A

(Cumitech 31A, Verification and validation of procedures in the clinical microbiology laboratory, ASM Press 2009)

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DisclaimerWhat I’m about to say on validation…

‘… is more what you’d call guidelines than actual rules’

Validation – AST Source of samples/isolates to test

> 30 well-characterized clinical isolates per panel that reflects the mix common to your population and also some with unusual AST patterns

Can include proficiency or commercial validation panels, but be wary: Reflective of your population? Incorrect sample matrix? If from the device manufacturer, a self-fulfilling prophecy?

Note that with care a single panel can be used for both AST and ID validations

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Validation – ASTHow to deal with discrepancies when two non-reference systems are compared?

No reference method, so grade results, then apply predetermined limits on the number and

types of discrepancies

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Validation – AST For each bug/drug result, calculate %s for…

Categorical (S/I/R) Errors Minor Error I vs S or I vs R Major Error S vs R or R vs S No Very Major Error category: ‘True’ result is not known

Essential Errors (> + 1 MIC dil. difference) Can only score when both methods generate discrete

numbers (i.e. do not score < or > values)

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Validation – ASTUsing the total number of evaluable bug/drug data points, an acceptable validation has:

< 5% Major Errors AND < 10% Major + Minor Errors AND < 10% Categorical Errors AND < 10% Essential Errors

Also look for trends in a particular drug or bug which may point towards a problem area

Consult your vendor rep with any validation problems

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Validation – AST Precision (reproducibility)

Test five isolates X3 for three to five days

Calculate intra-and inter-run categorical and essential % agreements

Isolates should have known susceptibility profiles, such as ATCC strains

Use both Gram positive and Gram negative strains if validating GP and GN panels

Acceptable precision > 95%agreement

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Validation – ID Test a range of Gram positive and Gram negative organisms ID’d by reference or current method(s)

Minimum of 20 patient isolates; larger labs test more. Additionally, test QC strains

< 10% discrepancies between reference and new IDs

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Validation – ID Level of agreement may need to be adjusted

e.g. Old ID of ‘Coag-negative Staphylococcus sp’ New instrument ID’s to species level

Precision Test 2-4 isolates X3 for three to five days Calculate % intra- and inter-run agreements Accept > 95% agreements

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Validation What to do if validation fails? Do not use

the new test and either…

Withdraw test from further consideration OR

Develop and implement a corrective plan with the manufacturer. Then, re-validate

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Verification – Component of the QA Process

An ongoing, multi-faceted process that assures the validated test continues to perform at the expected level

Personnel competency Proficiency challenges

QC organisms or analytes Comparison with other labs

Instrument PM/calibration Trend analysis

Discrepant resolution Pre- and post-analytic controls

Written procedures documenting the process

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Quality Control

I think, therefore I control quality

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iClick? 2You have an instrument that uses micro-broth dilution MIC plates in your lab. This system incubates and reads plates automatically but also has a manual plate reader. Your tech rep tells you to read a plate manually if QC fails on the instrument. If QC then passes, your QC is acceptable for the entire system and no follow-up action is needed.

1.True2.False

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iClick? 2: discussionQC is performed to assure the accuracy of a test result by assessing all analytical components

Reagents Instrument (where applicable) Test precision (i.e. repeatability) Operator technique Data interpretation

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CAP on AST QC‘For AST of either disk or dilution type,

control organisms are tested with each new lot or batch of antimicrobials or media and each day the test is performed thereafter.’

(Note that >3 failures per month per drug/bug combo is unacceptable)

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CAP on AST QC‘However, the frequency of test monitoring

may be reduced to weekly …if the laboratory can document satisfactory performance with

daily control tests as suggested by CLSI guidelines.’

The CAP checklist then goes on to briefly describe how to do so

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AST QC ResourcesCOLA, JC have similar verbiage, but is the checklist guidance enough?

IMHO*, No!

You need CLSI AST documents in your lab.

(*In my humble opinion.)

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CLSI AST Documents M2 (disk diffusion) and M7 (MIC), 3 year cycle

Test performance QC (including daily-to-weekly QC)

M100, annual cycle Recommended drugs to test and report, interpretive breakpoints QC strains, QC troubleshooting, when to re-validate QC

Others documents for other classes of microorganisms

(Explore these and more at http://www.clsi.org/; choose Microbiology from the Shop drop down menu)

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iClick? 3How many of you have these CLSI documents in your lab:

1. 2012 M2 (disk diffusion), M7 (MIC) and M100 (Breakpoints, QC)

2. 2012 M7 and M1003. 2012 M2 and M1004. 2012 M2 and M75. Any older versions of these documents6. None of the above

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Conversion to Weekly AST QCWhen day-of-use QC is being successfully performed at least once a week, a lab may consider weekly AST QC by a validation process:

Test QC strains 20 or 30 consecutive days If 0-1 failures per drug-bug combo in 20 days

OR 2-3 failures in 30 days

THEN Weekly QC may be implemented

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Weekly AST QC Perform QC testing once per week and

with any new reagent If weekly AST QC fails

If readily identifiable error (e.g. wrong QC strain; see M2 or M7 for more examples) correct error and retest once. If QC passes, document findings and continue weekly QC

If no error is found…

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Weekly AST QC Re-validationPerform 5 consecutive days of QC on the failed drug-bug combo

(We automatically take out a fresh QC strain from the freezer at this point)

If ALL 5 days pass, document and resume weekly testing

If a failure occurs again, STOP TESTING and thoroughly evaluate the process for error

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New QC strain New lot of reagent

Correct process errors Consult the manufacturer

Weekly AST QC Re-validation Once a likely error has found, re-validate

Do not include data from the prior 5-day sequence Must again pass these criteria

0-1 failures per drug-bug combo/20 days OR 2-3 failures per drug-bug combo/30 days

Remember that, during re-validation the lab is on a daily QC schedule-a failure means that that drug’s results are not released

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AST QC References Disk diffusion

M02-A11 Section 15 M100-S22 Tables 3C, 3D

MIC M07-A9 Section 16 M100-S22 Tables 4F, 4G

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AST QC Special Considerations

M100-S22 Tables 3C & 4F, ‘Reference Guides to QC Frequency’

When and how much re-validation to perform when a system change occurs (e.g. AST instrument repair, Abx formula change & Etc)

Release of patient results when QC fails? CLSI says OK with many qualifiers, but our

lab generally just says No

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iClick? 4You are performing a weekly AST QC re-validation for drug X on your favorite automated ID/AST instrument when you incur a failure on the same AST panel for drug Y. What do you do?

1. Ignore the failure of drug Y and press on with the 5-day testing of drug X

2. Now treat the failure of drug Y as a second failure and start a 5 day test of drug Y

3. Stop testing, evaluate the whole process, then perform a new 20/30 day validation on the whole AST panel

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iClick? 4 discussionThe correct answer isn’t clear, but Marshfield Labs treats the failure of the second drug as a failure and starts a 5 day test on that drug also

Why? Subsequent failures may reflect a larger problem

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ID QCCLIA requires a lab to show positive and negative reactions for each new lot and/or shipment of biochemical.

This includes kit and automated instrument ID methods!

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RapID ANA II Identification System Quality Control Each new lot number and/or shipment is to be tested with the following Lot#/Exp Date ________________________________ organisms to provide at least one positive and one negative reaction Set-up Date/Time/Init. __________________________ for each biochemical within the ID system. Read Date/Time/Init. ___________________________ Results Acceptable? ___________________________ Expected Results:

Before Reagent Addition After reagent addition

Organism URE BLTS ARA ONPG GLU GLU GAL FUC NAG PO4 LGY GLY PRO PAL ARG SER PYR IND

Clostridium sordellii

ATCC 9714

E + - - - - - - V - - - V + V V V V +

A

Bacteroides distasonis

ATCC 8503

E - + V + + + + - + + + + - + + + + -

A

Bacteroides uniformis

ATCC 8492

E - + + + + + + + + + + - - - - - - +

A

+ positive, - negative, V variable, (-) usually negative, (+) usually positive E = Expected Reactions A = Actual R

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ID QCThere is a QC solution for automated ID

instrument users:

Streamlined QC

Stay Tuned for the Next Talk!

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The End

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