Laboratory Quality Control .ppt

Lab

1. Laboratory Quality
Control

2. Quality assurance(QA)
Quality assurance(QA) refers to the planned and
systematic activities implemented in a quality system
so that quality requirements for a product or service
will be fulfilled. It is the systematic measurement,
comparison with a standard, monitoring of processes
and an associated feedback loop that confers error
prevention.
QA in Laboratory medicine is the means by which
reliability, precision and accuracy of investigations
used in support of optimal patient care can be
achieved

3. Quality Assessment
QualityAssessment-qualityassessment
(alsoknownasproficiencytesting)isameans
todeterminethequalityoftheresults
generatedbythelaboratory.Quality
assessmentisachallengetotheeffectiveness
oftheQAandQCprograms.
QualityAssessmentmaybeexternalor
internal

4. QC Assessment
External QC:
External Quality Assurance (EQAS)
Interlab
Internal QC
Replicate / Split Sample
Retained
Recheck / Repeat Sample

5. Stages of Quality Assurance
1: Pre Analytical
2: Analytical
3: Post Analytical

6. Pre-Analytical
Decision
Order request
Sample collection
Transport and
storage

7. •Errors made in
the period prior
to the analysis of
the sample ...
•may influence
the quality of
the final
measured
results ...
•and compromise
the diagnosis and
treatment of the
patient

8. Analytical
Analysis
Quality Control
Maintenance &
Service

9. Quality Control
Quality Control -QC refers to the measures
that must be included during each assay run
to verify that the test is working properly.
Quality Control is the study of those error
and Procedures used to recognize and
minimize them.
Process or system for monitoring the quality
of laboratory testing, and the accuracy and
precision of results

10. The QC system is designed to:
Provide routine and consistent checks to
ensure data integrity, correctness, and
completeness;
Identify and address errors and omissions;
Document and archive inventory material and
record all QC activities.

11. Design a QC Program
Establish written policies and procedures
Corrective action procedures
Train all staff
Design forms
Assure complete documentation and review

12. QC in Medical Microbilogy Lab.
Equipment Control:
All equipment is monitored daily to maintain
appropriate temperature (waterbaths, autoclave,
refrigerators and incubators.) Any temperature variance
outside the established range may affect the client’s
laboratory results.
B. Media / BoichemicalControl:
Media can be made in-house or purchased from media
companies .Sterlityand performance of the media is
done. If OK then the batch of media is releazedfor
routine work.

13. Reagent Control:
Reagents used should be tested utilizing positive and
negative controls. The quality of gram stain reagents is
checked with known bacterial cultures.
Antimicrobial Disc Control:
All antibiotic susceptibility discs should be checked
against ATCC cultures every week and also omreceipt
of antibiotics . The zone diameter of zone of inhibition
should be according to CLSI guidelines .

14. Stock Culture Control:
Cultures themselves must be tested periodically to
ensure viability and performance.
Specimen Collection and Control:
Protocols must be followed for proper collection of
client’s specimens.

15. Variables that affect the
quality of results
Theeducationalbackgroundandtrainingofthe
laboratorypersonnel
The condition of the specimens
The controls used in the test runs
Reagents
Equipment
The interpretation of the results
The transcription of results
The reporting of results

16. Errors in measurement
Truevalue-thisisanidealconceptwhich
cannotbeachieved.
Acceptedtruevalue-thevalueapproximating
thetruevalue,thedifferencebetweenthetwo
valuesisnegligible.
Error-thediscrepancybetweentheresultofa
measurementandthetrue(oracceptedtrue
value).

17. Sources of error
Inputdatarequired-suchasstandardsused,
calibrationvalues,andvaluesofphysicalconstants.
Inherentcharacteristicsofthequantitybeing
measured-e.g.CFTandHAItitre.
Instrumentsused-accuracy,repeatability.
Observerfallibility-readingerrors,blunders,
equipmentselection,analysisandcomputation
errors.
Environment-anyexternalinfluencesaffectingthe
measurement.
Theoryassumed-validityofmathematicalmethods
andapproximations.

18. Random Errors x
x x
x x
True x x x x
Value x x x
x x x
x
x
x

19. Systematic Errors x
x x x x x x x
True x
Value

20. QC on the Basis of Method
Quantitative test
measures the amount of a substance
present
Qualitative test
determines whether the substance being
tested for is present or absent

21. Qualitative QC
Quality control is performed for both,
system is somewhat different
Controls available
Blood Bank/Serology/Micro
RPR/TPHA
Dipstick technology
Pregnancy

22. Quantative QC
Need data set of at least 20 points,
obtained over a 30 day period
Calculate mean, standard deviation,
coefficient of variation; determine
target ranges
Develop Levey-Jennings charts, plot
results

23. Accuracy and Precision
The degree of fluctuation in the
measurements is indicative of the
“precision” of the assay.
The closeness of measurements to the
true value is indicative of the “accuracy”
of the assay.
Quality Control is used to monitor both
the precision and the accuracy of the
assay in order to provide reliable
results.

24. Precision and Accuracy
Precise and
inaccurate
Precise and
accurate

25. Standard Deviation and
Probability
For a set of data with a
normal distribution, a
value will fall within a
range of:
+/-1 SD 68.2% of the
time
+/-2 SD 95.5% of the
time
+/-3 SD 99.7% of the
time

26. Monitoring QC Data
Use Levey-Jennings chart
Plot control values each run, make
decision regarding acceptability of run
Monitor over time to evaluate the
precision and accuracy of repeated
measurements
Review charts at defined intervals, take
necessary action, and document

27. Levey-Jennings Chart
A graphical method for displaying
control results and evaluating whether a
procedure is in-control or out-of-control
Control values are plotted versus time
Lines are drawn from point to point to
accent any trends, shifts, or random
excursions

28. Record and Evaluate the Control Values

29. Shewhart Control Charts
AShewhartControlChartdependonthe
useofIQCspecimensandisdevelopedin
thefollowingmanner:-
PutuptheIQCspecimenforatleast20or
moreassayrunsandrecorddownthe
O.D./cut-offvalueorantibodytitre
(whicheverisapplicable).
Calculatethemeanandstandarddeviations
(s.d.)

30. Shewhart Control Charts
Makeaplotwiththeassayrunonthex-axis,
andO.D./cut-offorantibodytitreonthey
axis.
Drawthefollowinglinesacrossthey-axis:
mean,-3,-2,-2,1,2,and3s.d.
PlottheO.D./cut-offobtainedfortheIQC
specimenforsubsequentassayruns
Majoreventssuchaschangesinthebatchno.
ofthekitandinstrumentsusedshouldbe
recordedonthechart.

31. Shewhart Chart

32. Westgard rules
Therearesixcommonlyused
Westgardrulesofwhichthreeare
warningrulesandtheotherthree
mandatoryrules.
Theviolationofwarningrules
shouldtriggerareviewoftest
procedures,reagentperformance
andequipmentcalibration.
Theviolationofmandatoryrules
shouldresultintherejectionof
theresultsobtainedwithpatients’
serumsamplesinthatassay.
1
2Srule
1
3Srule
2
2Srule
R
4Srule
4
1Srule
10
Xrule

39. Westgard Multirule QC

40. When a rule is violated
Warning rule = use other rules to inspect
the control points
Rejection rule = “out of control”
Stop testing
Identify and correct problem
Repeat testing on patient samples and
controls
Do not report patient results until
problem is solved and controls indicate
proper performance

41. Solving “out-of-control”
problems
Policies and procedures for remedial
action
Troubleshooting
Alternatives to run rejection

42. Post Analytical
Interpretation of data
Data management
Reporting
Treatment of patient

43. Summary
Quality Control program validates test
accuracy and reliability of investigations
used in support of optimal patient care.

44. Reference
Text book of Medical Laboratory
Technology by Praful B. Godkar
Hemostasis & Quality Assurance by
Manipal University
http://www.ncbi.nlm.nih.gov/pmc/arti
cles/PMC2213906/
http://www.westgard.com/westgard-
rules/

45. THANK YOU