Step by Step troubleshooting Internal and External Quality Assessments

1. Troubleshooting IQC/EQA
Dr. Bikash Chaudhury
HOD Biochemistry

2. Learning Objectives

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

4. → Quality control in the medical laboratory is a statistical
process used to monitor and evaluate the analytical process that
produces patient results.
→ Quality control refers to the measures that must be included
during each assay run to verify that the test is working properly

5. → Quality Assurance is defined as the overall program that
ensures that the final results reported by the laboratory are
correct.
i. Quality assurance means quality enhancement
ii. Quality assurance aims at ensuring that the data provided are reliable
and relevant
iii. Quality assurance involves all measures that can be taken to improve
laboratory efficiency and effectiveness.
iv. It ensures laboratory performance with minimum risk for laboratory
workers and gives maximum benefit to the individual and community

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

7. 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”)
“The aim of quality control is simply to ensure that the results
generated by the test are correct. However, quality assurance is
concerned with much more: that the right test is carried out on the
right specimen, and that the right result and right interpretation is
delivered to the right person at the right time”

8. → Also known as proficiency testing
→ Quality Assessment is a means to determine the quality of
the results generated by the laboratory
→ Quality Assessment is a challenge to the QA and QC
programs
→ Quality Assessment may be external or internal, examples
of external programs include EQAS, RIQAS, etc

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

12. Outside laboratory
Within laboratory
Sample
handling
Patient
preparation
Requisition
Sample
receivingSample
Collection
Sample
Transport
Patient
Doctor
Analysis
Reports
Results

13. → Specimen
→ Collection technique
→ Storage and transportation
→ Quantity
→ Labeling
→ Mismatch of sample
→ Laboratory : No necessary
test capacity

14. 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,
Aptitude, Competence,
Commitment, 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, instructions and
records, quality control
procedures and recorded test
results involved in providing a
service or the manufacture of a
product
Assessment

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

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

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

18. • 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.

21.  True value - The known, accepted value of a
quantifiable property
 Accepted true value - the value approximating the
true value, the difference between the two values is
negligible.
 Error - the discrepancy between the result of a
measurement and the true (or accepted true value).

22. • Input data required - such as standards used, calibration values, and
values of physical constants.
• Inherent characteristics of the quantity being measured
• Instruments used - accuracy, repeatability.
• Observer fallibility - reading errors, blunders, equipment selection,
analysis and computation errors.
• Environment - any external influences affecting the measurement.
• Theory assumed - validity of mathematical methods and
approximations.

23. 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

25. • An error which, in the course of a number of measurements of the
same value of a given quantity, remains constant when
measurements are made under the same conditions, or varies
according to a definite law when conditions change.
• Systematic errors create a characteristic bias in the test results and
can be accounted for by applying a correction.
• Systematic errors may be induced by factors such as variations in
incubation temperature, blockage of plate washer, change in the
reagent batch or modifications in testing method.

30. • 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

31. mg/dlS 1N
)x(x 2
1
 

variance

32. • 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 +3s
X

33. • 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

35. 80
85
90
95
100
105
110
115
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD

36. • 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

37. • 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

38. • Consider using Westgard Control 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

39. • “Multirule Quality 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

40. 12S rule
13S rule
22S rule
R4S rule
41S rule
10X rule
Used when 2 levels of
control material are
analyzed per run.

41. • “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 13S rule

42. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
12S rule
violation

43. • If either of the two control
results falls outside of
±3SD, rule is violated
• Run must be rejected
• If 13S not violated, check 22S

44. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
13S rule
violation

45. • 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

46. 22S Rule = Reject the run when 2 consecutive control
measurements exceed the same
+2SD or -2SD control limit
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
22S rule
violation

47. • 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

48. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
R4S rule
violation

49. • 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

51. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Mean
Day
+1SD
+2SD
+3SD
-1SD
-2SD
-3SD
10x rule
violation

52. • 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

56. Troubleshooting EQA
Root Cause Analysis

57. EQA Participation
Recommended
for all laboratories
Required by ISO
Clause 5.6
ISO 15189

58. EQA Should Lead to Corrective Actions
“Corrective Action”
An action taken to correct a problem or deficiency

59. Steps for Corrective Action

60. Root Cause Analysis

61. Transcription Error

62. Pre-survey issues

63. Sample receipt/handling

64. Test Performance

65. Data Handling EQA Provider

66. Report and Interpretation

67. Random Error ?

68. EQAS Troubleshooting Checklist

69. Take Corrective Actions
 Use problem-solving team:
Investigate root causes
Develop appropriate corrective actions
 Implement corrective actions
 Examine effectiveness
 Record all actions and findings

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

71. • 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

72. Keys to successful quality control
 Adequately trained, interested and
committed staff.
 Common-sense use of practical
procedures.
 Willingness to admit and rectify mistakes.
 Effective communication.
72

73. Take Home Message
 A quality assurance (QA) programme is essential for improving the reliability,
efficiency and use of laboratory services in order to achieve the required
technical quality in laboratory diagnosis.
 The process of quality assurance should be continuous and monitored
 Quality assurance is the responsibility of all laboratory technicians and
supervisors.
 It is useful periodically to calculate indicators to evaluate the performance of
the laboratory.
 It is not sufficient in QC simply to identify errors or weaknesses in laboratory
services; remedial action must be taken to permanently remove them.