Quality Control
Quality assurance
in laboratories
May 2007
E P I D E M I C
Laboratory Training for Field Epidemiologists
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Learning objectives
•
At the end of the presentation, participants should
–
Understand the principles of Quality control
–
Understand the importance for internal and external quality control schemes
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Quality is....
• invisible when
GOOD
• impossible to ignore when
BAD
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Quality ?
•= sum-total of all the characteristics
of a product/service that has a
bearing upon the utilization of the
product/service to the entire
satisfaction of the consumer
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Quality ?
•Consistency
– Accuracy
– Precision
•Right result
– First time
– Every time
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Objectives of quality in lab
• Support provision of high quality health-care
– Reduce morbidity
– Reduce mortality
– Reduce economic loss
• Ensure credibility of lab
• Generate confidence in lab results
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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
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Quality assurance =
Internal quality control +
External quality assessment
Continuously and
concurrently assessing
lab work
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Retrospectif and
periodic
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Assessment of Quality System
Man-driven
• Audit, On-site
Material-driven
• Quality Assessment
inspection
• Internal
• Internal
• External
• External
• Schematic way:
External Quality
Assessment Scheme
(EQAS)
• Accreditation
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1 - Internal quality control
in laboratory
•
= set of procedures undertaken by the staff to ensure quality of
reports
•
Total process beginning with sample collection up to final
reporting
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Quality in labs is mutual responsibility of…..
• Laboratory specialists
• Clinicians
• Public health physicians
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Factors influencing internal quality
Sample
Transport
Sample
handling
Sample
receiving
Sample
Collection
Analysis
Patient
preparation
Outside laboratory
Within laboratory
Requisition
Results
Patient
Reports
Doctor
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1.1 - Factors influencing quality:
Pre-analytical
• Investigation
–
Right
Ex: blood culture in the first week of enteric fever and not Widal
• Specimen
–
Ex: No stool in SARS
• Collection technique
–
Ex: Stool from bedpan→ collect stool in a clean container
• Storage and transportation
–
Ex: Not kept in cold chain- overgrowth of other bacteria
• Quantity
–
Ex: Not enough serum for serology
• Labeling
–
Ex: Mismatch of sample
• Laboratory
–
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Ex: Not necessary test capacity
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1.2 - Factors influencing quality:
Analytical
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
REAGENTS STABILITY, INTEGRITY
AND EFFICIENCY:
Stable, Efficient, Desired quality,
Continuously available, Validated
EQUIPMENT RELIABILITY:
Meet technical needs, Compatible, User
& maintenance friendly, Cost effective,
Validated
SPECIFICITY & SENSITIVITY OF
SELECTED TEST:
Adequate ST, Sufficient SP, cost
effective, compatible with,
available infrastructure and
expertise, interpretable, meets the
needs/ objectives, validated
ANALYTICAL
FACTORS
DOCUMENTATION:
Assessment
All the written policies, plans,
procedures, instructions and records,
quality control procedures and recorded
test results involved in providing a
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Laboratory Training for Field Epidemiologists
service
or the manufacture of a product
Procedural
reliability using
Standard
Operating
Procedures
N S E
Documentation
• If you have not documented it,
•
you have NOT done it …
• If you have not documented,
•
it is a RUMOUR !!!
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Value of Documentation
•
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
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Standard Operating Procedures (SOP)
• = comprehensively written
document that describes the
laboratory procedure and all other
related issues
SOP for Gram Staining
• Essential for ensuring uniformity in
laboratory procedures
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Validation
•
= is about determining whether
something does what it is supposed to
do
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Importance of validation
•
Validation - before you introduce something
•
Re-validation
– after you have changed/modified
– periodic
•
Validation is applied to:
– SOP
– reagents
– equipment
– software
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1.3 - Factors influencing quality:
Post-analytical
• Right recording and reporting
• Right interpretation
– Range of normal values
• Right turnaround time
• Report to right user
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Reporting
•
Unequivocal message
•
Numerical value with units as and when required
KISS !
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(Keep it short and simple)
R E S P O N S E
Bottom-line
•Quality costs ,
•but poor quality costs more …
€
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Training
•
The quality system is only as good as the staff who actually
work with it
•
No matter how good the quality system is on paper, quality
cannot be achieved if the theory cannot be translated into
practice
•
Training policy and plan
•
Training must include an understanding of why quality is
important
•
Training should be need based, for all staff and reviewed
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2 - External Quality Assessment
•
3 types, mainly 2:
•
An EQA organizer provides surveys in which identical material will
be tested by all participating laboratories
•
 ex: WHO/NHLS programme in Africa
•
Participating laboratories send specimens to EQA organizer for
Rechecking
•
 ex: Tuberculosis bacilloscopy quality control in Morocco
•
On-site visits with physical assessment)
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EQA
•
According to the ISO definition, EQA (also known as ‘proficiency
testing’ (PT) or ‘EQ Control = EQC’) refers to:
•
a system of objectively checking laboratory results by means of an
external agency
•
including comparison of a laboratory's result at intervals with those
of other laboratories
•
the main objective being the establishment of trueness
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What makes microbiology different to other
EQA schemes?
•
Microbiology samples are fundamentally non-uniform.
•
Microbiological taxonomy is fundamentally imprecise.
•
Microbiological samples are changing.
•
Traditional microbiological analysis depends upon behavior, not
constitution.
•
Microbiology has many “right” answers.
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Objectives of EQA schemes for laboratories
•
Laboratory oriented objectives:
•
1. Identifying possible deficiencies in laboratory practice, and guiding
participants in any corrective actions to be taken for improvement;
•
2. Identifying the reliability characteristics of particular methods, materials
and equipment under routine conditions and suggest corrective actions as
appropriate;
•
3. Assessing and monitoring the impact of training; help for the
preparation of future trainings
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Objectives of EQA schemes for laboratories
•
Public health oriented objectives:
•
4. Providing the basis for the comparability of results during epidemiological
surveillance and disease control
•
5. Collecting information on laboratory measurements ( intra- and interlaboratory) to alert professionals and/or government bodies about problems
related to traceability and harmonization of results, and establish limits of
acceptability of results as appropriate for a given purpose;
•
6. Collecting information for the purpose of licensing or accreditation of
laboratories;
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2.1 Example of EQA organizer:
CMPT, Canada
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2-2 Rechecking (RC)
•
Participating laboratories send specimen to be rechecked on a
regular basis to the EQA body
•
Targeted specimens and/or randomized specimens
•
Usually blind, can be single or multiple
•
Example of tuberculosis bacilloscopy in Morocco:
– 180 centres in the country
– All positives smears (targeted)
– 10% of all negative smears (randomized)
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2.3 On-site visits
•
Laboratory assessment
•
Laboratory licensing and/or accreditation
•
Combined with the other types of EQA
•
–
After repeated problems (corrective action)
–
During on-site supervision (routine checking)
–
After training session (practical implementation of the training )
 In addition to the assessment of the existing conditions, QC material can also be
provided (slides, strain, sera, specimen for rapid tests …)
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The ideal situation: 2 types together
and very targeted on-site visits
•
On-site visits:
– Expensive, heavy
– Only for one laboratory
– Very much time consuming
– Very effective if motivated staff
– Very complementary to all other schemes especially rechecking
•
On-site visits should be used with « extreme » situations
– « Initial » situation: laboratory assessment, licensing
– « Bad » situation: repeated problems, failures in training
– « Good » situation: accreditation
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3- Accreditation
•
= process of inspection of laboratories and their licensing by a third party to
ensure conformity to pre-defined criteria
•
Very very long task (As example, around 20% of French laboratories are accredited by
COFRAC, it takes around 2-3 years to follow the roadmap)
•
Last step of the entire process
1. Quality assurance (procedures, way of working)
2. IQC
3. EQC
4. Networking of the laboratories
5. … and then only accreditation if 1-4 completed
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Carry home messages……..
•
Quality assurance measures what a lab can do to improve reliability
•
As an epidemiologist, you may engage the laboratory in a dialogue and
tactfully ask about QA measures in place
•
BE CAREFUL ! An epidemiologist is NOT in a position to assess the
reliability of the lab or to evaluate its QA procedures as this requires a
specific expertise
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To summarize
•The determinants that ensure the quality of the laboratory & therefore the specimen
results are:
INTERNAL QUALITY CONTROL:
Set of procedures undertaken by the staff
to ensure quality of reports
Pre-analytical
Analytical
Post-analytical
Investigation
Specimen
Collection
technique
Storage and
transportation
Quantity
Labeling
Laboratory
Proficiency of personnel
Recording and
reporting
Reagents stability, integrity and efficiency
Equipment reliability
Specificity & sensitivity of selected test
Procedural reliability using standard operating procedures
Use of appropriate controls
Documentation
Assessment
EXTERNAL QUALITY ASSESSMENT:
a system of objectively checking laboratory
results by means of an external agency
ACCREDITATION: Process of inspection of
laboratories and their licensing by a third
party to ensure conformity to pre-defined
criteria
External quality assessment scheme
Rechecking
On-site visits
Combination of any two or more of the above
Laboratory license
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Interpretation
Turnaround time
Quality Control
Developed by:
The Department of Epidemic and Pandemic Alert and
Response of the World Health Organization with the
assistance of:
European Program for Field Epidemiology
Training
Canadian Field Epidemiology Programme
Thailand Ministry of Health
Institut Pasteur
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