quality control in clinical laboratory

it focus on quality control

4. 1.Quality Control
2.Quality Assurance
3.Quality Assessment

5. → Qualitycontrolinthemedicallaboratoryisastatistical
processusedtomonitorandevaluatetheanalyticalprocessthat
producespatientresults.
→ Qualitycontrolreferstothemeasuresthatmustbeincluded
duringeachassayruntoverifythatthetestisworkingproperly

6. → QualityAssuranceisdefinedastheoverallprogramthat
ensuresthatthefinalresultsreportedbythelaboratoryare
correct.
i.Qualityassurancemeansqualityenhancement
ii.Qualityassuranceaimsatensuringthatthedataprovidedarereliable
andrelevant
iii.Qualityassuranceinvolvesallmeasuresthatcanbetakentoimprove
laboratoryefficiencyandeffectiveness.
iv.Itensureslaboratoryperformancewithminimumriskforlaboratory
workersandgivesmaximumbenefittotheindividualandcommunity

7. The Quality Assurance Cycle
•Data and Lab
Management
•Safety
•Customer
Service
Patient/Client Prep
Sample Collection
Sample Receipt
and Accessioning
Sample Transport
Quality Control
Record Keeping
Reporting
Personnel Competency
Test Evaluations
Testing

8. Quality Assurance vs. Quality
Control
Quality Assurance Quality Control
An overall
management plan to
guarantee the
integrity of data
(The “system”)
A series of
analytical
measurements used
to assess the
quality of the
analytical data (The
“tools”)
“Theaimofqualitycontrolissimplytoensurethattheresults
generatedbythetestarecorrect.However,qualityassuranceis
concernedwithmuchmore:thattherighttestiscarriedoutonthe
rightspecimen,andthattherightresultandrightinterpretationis
deliveredtotherightpersonattherighttime”

9. → Alsoknownasproficiencytesting
→ QualityAssessmentisameanstodeterminethequalityof
theresultsgeneratedbythelaboratory
→ QualityAssessmentisachallengetotheQAandQC
programs
→ QualityAssessmentmaybeexternalorinternal,examples
ofexternalprogramsincludeEQAS,RIQAS,etc

10. • Support provision of high
quality health-care
→Reduce morbidity
→Reduce mortality
→Reduce economic loss
• Ensure credibility of lab
• Generate confidence in
lab results

13. Outside laboratory
Within laboratory
Sample
handling
Patient
preparation
Requisition
Sample
receiving
Sample
Collection
Sample
Transport
Patient
Doctor
Analysis
Reports
Results

14. → Specimen
→ Collection technique
→ Storage and transportation
→ Quantity
→ Labeling
→ Mismatchof sample
→ Laboratory : No necessary
test capacity

15. EQUIPMENT RELIABILITY:
Meet technical needs, Compatible,
User & maintenance friendly, Cost
effective, Validated
Procedural
reliability using
Standard
Operating
Procedures
REAGENTS
STABILITY, INTEGRITY AND
EFFICIENCY:
Stable, Efficient, Desired
quality, Continuously
available, Validated
SPECIFICITY & SENSITIVITY
OF SELECTED TEST:
Adequate ST, Sufficient
SP, cost effective, compatible
with, available infrastructure
and
expertise, interpretable, meets
the needs/
objectives, validated
PROFICIENCY OF
PERSONNEL:
Education, Training, Aptitu
de, Competence, Commitm
ent, Adequate
number, CME, Supervision,
Motivation
USE OF APPROPRIATE
CONTROLS:
•Internal: Labs, Calibrated
against national
•External: Supplied by
manufacturer, National,
International
DOCUMENTATION:
All the written
policies, plans, procedures, inst
ructions and records, quality
control procedures and recorded
test results involved in providing
a service or the manufacture of a
product
Assessment

16. If you have not documented it,
you have NOT done it …
If you have not documented,
it is a RUMOUR !!!

17. •Ensures processes and outcomes are traceable
•Processes can be audited, thus external
assessments can take place
•Tool for training
•Reminds you what to do next

18. It is a comprehensively
written document that
describes the laboratory
procedure and all other
related issues
Essential for ensuring
uniformity in laboratory
procedures

19.  Right recording
and reporting
 Right interpretation
Range of normal values
 Right turnaround
time
 Report to right user

20. True Value
The known,
accepted value
of a
quantifiable
property
Measured Value
The result of an
individual’s
measurement of
a quantifiable
property

21. Accuracy
How well a
measurement
agrees with an
accepted value
Precision
How well a
series of
measurements
agree with each
other

22. •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.

25. Truevalue-Theknown,acceptedvalueofa
quantifiableproperty
Acceptedtruevalue-thevalueapproximatingthe
truevalue,thedifferencebetweenthetwovaluesis
negligible.
Error-thediscrepancybetweentheresultofa
measurementandthetrue(oracceptedtruevalue).

26. •Inputdatarequired-suchasstandardsused,calibrationvalues,and
valuesofphysicalconstants.
•Inherentcharacteristicsofthequantitybeingmeasured
•Instrumentsused-accuracy,repeatability.
•Observerfallibility-readingerrors,blunders,equipment
selection,analysisandcomputationerrors.
•Environment-anyexternalinfluencesaffectingthemeasurement.
•Theoryassumed-validityofmathematicalmethodsand
approximations.

27. Systematic Error
Avoidable error
due to
controllable
variables in a
measurement.
Random Errors
Unavoidable errors
that are always
present in any
measurement.
Impossible to
eliminate

29. •Anerrorwhich,inthecourseofanumberofmeasurementsofthe
samevalueofagivenquantity,remainsconstantwhen
measurementsaremadeunderthesameconditions,orvaries
accordingtoadefinitelawwhenconditionschange.
•Systematicerrorscreateacharacteristicbiasinthetestresultsand
canbeaccountedforbyapplyingacorrection.
•Systematicerrorsmaybeinducedbyfactorssuchasvariationsin
incubationtemperature,blockageofplatewasher,changeinthe
reagentbatchormodificationsintestingmethod.

33. •The standard deviation (SD) is the square root of the variance
•it is the square root of the average squared deviation from
the mean
•SD is commonly used (rather than the variance) since it has the
same units as the mean and the original observations
•SD is the principle calculation used in the laboratory to
measure dispersion of a group of values around a mean

34. mg/dlS
1N
)x(x
2
1 variance

35. •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
68.2%
95.5%
99.7%
Frequency
-3s-2s -1s Mean +1s+2s +3sX

36. •In general, laboratories use the +/-2 SD criteria
for the limits of the acceptable range for a test
•When the QC measurement falls within that
range, there is 95.5% confidence that the
measurement is correct
•Only 4.5% of the time will a value fall outside of
that range due to chance; more likely it will be
due to error

38. 80
85
90
95
100
105
110
115
123456789101112131415161718192021222324 Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD

39. •Ideally should have control values clustered about the mean
(+/-2 SD) with little variation in the upward or downward
direction
•Imprecision= large amount of scatter about the mean.
Usually caused by errors in technique
•Inaccuracy= may see as a trend or a shift, usually caused
by change in the testing process
•Random error = no pattern. Usually poor
technique, malfunctioning equipment

40. •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

41. •Consider using WestgardControl Rules
•Uses premise that 95.5% of control values should fall
within ±2SD
•Commonly applied when two levels of control are
used
•Use in a sequential fashion

42. •“MultiruleQuality Control” developed by Dr. James O. Westgard
based on statistical concepts
•Uses a combination of decision criteria or control rules
•Allows determination of whether an analytical run is “in-control”
or “out-of-control”
Dr. Westgard

43. 1
2Srule
1
3Srule
2
2Srule
R
4Srule
4
1Srule
10
Xrule
Used when 2 levels of
control material are
analyzed per run.

44. •“warning rule”
•One of two control results falls outside ±2SD
•Alerts tech to possible problems
•Not cause for rejecting a run
•Must then evaluate the 1
3S rule

45. 123456789101112131415161718192021222324 Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
1
2Srule
violation

46. •If either of the two control
results falls outside of
±3SD, rule is violated
•Run must be rejected
•If 1
3Snot violated, check 2
2S

47. 123456789101112131415161718192021222324 Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
1
3Srule
violation

48. •2 consecutive control values for the same
level fall outside of ±2SD in the same
direction, or
•Both controls in the same run exceed ±2SD
•Patient results cannot be reported
•Requires corrective action

49. 2
2SRule= Reject the run when 2 consecutive control
measurements exceed the same
+2SD or -2SD control limit123456789101112131415161718192021222324
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
2
2Srule
violation

50. •One control exceeds the mean by –2SD,
and the other control exceeds the mean by
+2SD
•The range between the two results will
therefore exceed 4 SD
•Random error has occurred, test run must
be rejected

51. 123456789101112131415161718192021222324 Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
R
4Srule
violation

52. •Requires control data from previous
runs
•Four consecutive QC results for one
level of control are outside ±1SD, or
•Both levels of control have consecutive
results that are outside ±1SD

54. 123456789101112131415161718192021222324 Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
10
xrule
violation

55. •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
•Solving “out-of-control” problems
Policies and procedures for remedial action
Troubleshooting
Alternatives to run rejection

60. It is a process of inspection of laboratories and their licensing by a
third party to ensure conformity to pre-defined criteria
Very verylong task (it may take around 2-3 years to follow the
roadmap)
Last step of the entire process
Quality assurance (procedures, way of working)
IQC
EQC
Networking of the laboratories
… and then only accreditation if 1-4 completed

62. •Qualityisa lousyidea…if itsonlyan Idea
•Qualityassurance measureswhata labcando to
improvereliability
•Validate all test accuracy and reliability
•ALWAYS,ALWAYS,ALWAYS:DOCUMENT THE
PROBLEM AND CORRECTIVE ACTIONS
TAKEN!!!!!