Role of EQA/Inter laboratory testing

Role of EQA/Inter laboratory testing
Dr. R.Selvakumar
CMC; Vellore
Quality is....
• invisible when GOOD
• impossible to ignore when BAD
Changes over a Century
2012
1912
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485 million
Poor Healthcare Infrastructure
Poor socioeconomic status
Time plenty, Money scarce
Communicable diseases
Clinical science
Caregiver driven Conservative mindset
Minimal regulatory control
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1.25 billion
Robust Healthcare Burgeoning middle class
Money plenty , Time scarce
Non communicable diseases
Technology driven
Patient driven
Informed mindset
Stringent regulatory control
Consequences of poor quality
• Inappropriate action
– Over‐investigation
– Over‐treatment
– Mistreatment
• Inappropriate inaction
– Lack of investigation
– No treatment
• Delayed action
• Loss of credibility of laboratory
• Legal action
Factors influencing internal quality Sample
Transport
Sample
handling
Sample
Collection
Sample
receiving
Analysis
Patient
preparation
Outside laboratory
Within laboratory
Requisition
Results
Patient
Doctor
Reports
Factors influencing quality
PROFICIENCY OF
PERSONNEL:
Education, Training,
Aptitude, Competence,
Commitment, Adequate
number, CME, , Motivation
USE OF APPROPRIATE
CONTROLS:
• Internal: Labs, Calibrated
against national
• External: Supplied by
manufacturer, National,
International
Assessment
REAGENTS STABILITY,
INTEGRITY AND EFFICIENCY:
Stable, Efficient, Desired quality,
Continuously available, Validated
EQUIPMENT RELIABILITY:
Meet technical needs, Compatible,
User & maintenance friendly, Cost
effective, Validated
ANALYTICAL
PERFORMANCE
DOCUMENTATION:
All the written policies, plans,
procedures, instructions and
records, quality control procedures
and recorded test results involved in
providing a service
SPECIFICITY & SENSITIVITY
OF SELECTED TEST:
Adequate ST, cost effective,
compatible with, available
infrastructure and expertise,
interpretable, meets the
needs/ objectives, validated
Procedural
reliability using
Standard
Operating
Procedures
Laboratory Mistakes in Stat Testing
Types of Mistakes
Department
Preanalytical
Analytical
Postanalytical
No.
%
No.
%
No.
%
Intensive
care
39
67
6
10
12
23
Surgery
26
81
5
16
1
3
Medicine
33
61
9
17
12
22
Nephrology
31
69
5
11
9
20
Total
129
68.2
25
13.3
35
18.5
Phlebani and Carraro Clin Chem 43:1348, 1997
History of EQAS
1946 1953 1966 1970 1971 1975 -
Belk & Sunderman (USA)
Clinical Chemistry (UK)
Finland Lab quality, Clinical Chemistry
Regional Clinical survey, Uppsala
Med. Microbiology –NEQAS (UK)
EQALIS – national survey in most areas
of lab medicine
1978 - ACBI / CMC EQAS
1980 - Survey in medical microbiology
1982 - Project SEQLA
Pilot QC survey – Christian Medical College and
Hospital, Vellore,
April 1977.
Constituent
No. of Labs
reporting
Range of values
reported mg%
Acceptable
results
Sugar
Urea
Cholesterol
Calcium
36
40
42
20
57 – 173
15 – 80
120 – 288
5.7 – 15.2
61%
53%
38%
55%
First QC survey done by CMC
Lab. No.
1
2
3
4
5
Glucose
mg/dl
114, 107, 109, 114
108, 112, 114, 110
82, 84, 83, 84
172, 169, 170, 174
66, 130, 83, 127
Acceptable Range 102 - 118
Mean
110
Proficiency Testing (PT)

External peer - comparison program
 Approved PT required if available
 Alternative PT if external not available
- Split samples testing
- Testing of known specimens
- Clinical validation by chart review

Integrated with routine workload

Evaluation and corrective action
What is EQA ?
EQA is a part of the quality menu of the
laboratory.
It aims to analyse the accuracy of the entire
testing procedure from the receipt of the
sample and testing to reporting of the
results.
10 commandments for Sample Quality
 Thou shall not overly clench fist at collection
 Thou shall not leave tourniquet on for too long
 Thou shall draw tubes in proper sequence
 Thou shall draw correct volume of blood
 Thou shall mix specimen adequately
 Thou shall wait till serum tube fully clots
 Thou shall centrifuge at proper speed & time
 Thou shall not re-spin primary tubes
 Thou shall not pour but aspirate to 2nd container
 Thou shall store sample under proper conditions
QUALITY CONTROL
QC is the most important and often least appreciated activity in the laboratory
Every laboratory must know that QC is an obligation to the patient
Every laboratory should strive to give an accurate test result for an analyte which is as close as possible to the “true” value for that analyte.
QC helps to improve precision and accuracy.
QC helps to reduce errors and to give both the laboratory personnel and the clinician confidence in the results.
May be required for accreditation.
Internal QC [Precision]
QC
External QC [Accuracy]
[Proficiency Testing]
INTERPRETATION OF QC DATA
According to WHO an analytical system is out of control if one of the four criteria is met.
 A QC value lies entirely outside the control limit
 Seven consecutive values show a rising tendency
 Seven consecutive values show a falling tendency
 Seven consecutive values lie on the same side of the mean
WESTGARD’S WARNING RULE
Use of QC at one or two different levels will provide valuable information on the type of error.
 12S –One control observation exceeding mean ± 2s ‐ warning
 1 3S ‐ one observation is ±3 SD of the mean –
rejection – Random error
 2 2S ‐ two observations of the same level QC are more than mean ± 2 SD ‐ rejection ‐ systematic error
R 4S ‐ difference between two observations within the run is more than 4 SD – rejection – random error
4 1S ‐ four consecutive observations are > 1SD
‐ rejection – systematic error
10 X ‐ ten consecutive observations are on the same side of the mean ‐ rejection – systematic error
Plasma Glucose concentration
Levey Jennings Chart for Glucose 95% confidence limits 150 + 6 mg%
156
154
152
150
148
146
144
142
2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
Days
Good practices in testing PT samples
 PT samples must be tested with the laboratory’s regular samples.
 PT samples must be tested the same number of times that patients samples are tested.
 Laboratories should not send PT samples to another laboratory for analysis
Laboratories must not engage in inter laboratory comparison of PT sample results before these results are submitted to the sponsor of the PT programme by the required report date.
Laboratories must document all steps like handling, processing, testing and reporting of PT sample.
Characteristics of a good QC material
 The analyte concentration should be at medically significant levels.
 The material should be available in large quantities.
 The material matrix should be as much like the human sample as possible.
 Constituents should be stable for a long period of time.
 The material should have low vial to vial variability
 After the vial has been opened and the material prepared, it should be stable during the period of use.
 The material should be ready to use or require minimum preparation.
 Control material should be reasonably priced
ALTERNATIVE APPROACHES
Whenever EQAS samples are not available the labs may use other appropriate materials as
•
•
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Certified reference materials
Samples previously examined
Material from cell or tissue repositories
Exchange of samples from other labs
Control materials that are tested daily in interlaboratory comparison programmes.
VELLORE
Quality Assurance is a journey and not a
Destination
In other words:
Organisations should be striving for
continual improvements to their Quality
Management System
CONCLUSION
The pathology can be found in a patient but not in the laboratory

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