QUALITY ASSURANCE OF TESTING OPERATIONS

1
QUALITY ASSURANCE OF TESTING OPERATIONS

• Thomas L. Hearn, Ph.D.
• Deputy Director
• Division of Laboratory Systems
• Public Health Practice Program Office

2
Quality Assurance

• Planned and systematic activities to provide
  adequate confidence that requirements for quality
  will be met (ISO 8042, 3.4 NCCLS)

3
Class Exercise Describe the Steps in a Routine
Process
4
T h e W a l l S t r e e t J o u r n a l
Monday February 2, 1987 Medical Labs,
Trusted as Largely Being Error -Free, Are Far
From Infallible
5
(No Transcript)
6
Benefits of Laboratory Quality Assurance

• QA provides evidence of good performance
• Laboratory mistakes are prevented
• Significant improvements in testing performance
  can be achieved
• Research findings from the College of American
  Pathologists, the University of Wisconsin, and
  the Centers for Disease Control and Prevention

7
Why Is Quality Assurance of Testing Important ?

• Public expects high quality
• Defines parameters quality goals
• Evaluation improvement system
• Assures reliability comparability of results
• Cost effective
• Even the simplest of testing is not foolproof

8
Questions to Ask In Assessing a National QA System

• How is testing organized in-country?
• Who makes testing policies?
• Is there any central oversight?
• Are laboratories required to have QA programs?
• Which international agencies are, or were, active
  in technical assistance

9
Questions to Ask In Assessing a National QA System

• How are decisions made about which tests can be
  used?
• At the national level, who has authority
  responsibility for QA?
• What is the role of laboratory directors
  (national, provincial, and district) in QA?
• How is training provided?

10
Quality Assurance

• Planned and systematic activities to provide
  adequate confidence that requirements for quality
  will be met (ISO 8042, 3.4 NCCLS)

11
Testing Process
Analytic Specimen processing Specimen
storage Reagent preparation Equipment checks Test
performance
Post-Analytic Results review Quality control
review Report test results Results interpretation
Pre-Analytic Test selection Patient
instructions Test requisition Collect, label,
transport specimen
12
Quality Assurance Model U.S. Laboratory
Regulations
STAFF
Q
P
C
T
13
Quality Assurance (QA)

• Staffing / personnel
• Quality control (QC)
• Proficiency testing (PT) aka External quality
  assurance (EQA)

14
Staffing Components

• Able to execute responsibilities of director,
  supervisor, testing personnel
• Appropriate educational credentials
• Appropriate experience
• Receive training
• Competency assessments

15
Quality Control of theTesting Process
Analytic Specimen processing Specimen
storage Reagent preparation Equipment checks Test
performance
Post-Analytic Results review Quality control
review Report test results Results interpretation
Pre-Analytic Test selection Patient
instructions Test requisition Collect, label,
transport specimen Safety
16
Pre-Analytic QC Components

• Safety
• Specimen collection and handling
• Test requisition and records
• Referral for testing

17
Analytic QC Components

• Facilities
• Test methods, equipments, reagents, supplies
• Validation of test methods
• Equipment checks
• QC monitoring procedures
• Procedure manual

18
Analytic QC Components

• Facilities
• Test methods, equipments, reagents, supplies
• Procedure manual
• Validation of test methods
• Equipment checks
• QC monitoring procedures

19
Sensitivity, Specificity, and Prevalence

• If,
• prevalence 20
• sensitivity 80
• specificity 80
• Then,
• predictive value of positive 50
• predictive value of a negative 94.1

If, prevalence 20 sensitivity
99.9 specificity 99.9 Then, predictive
value of positive 99.6 predictive value of a
negative 100
20
Sensitivity, Specificity, and Prevalence
If, prevalence 0.15 sensitivity
95 specificity 95 Then, predictive value
of positive 2.8 predictive value of a negative
100
If, prevalence 0.15 sensitivity
99.9 specificity 99.9 Then, predictive
value of positive 60 predictive value of a
negative 100
21
Analytic QC Components

• Facilities
• Test methods, equipments, reagents, supplies
• Procedure manual
• Validation of test methods
• Equipment checks
• QC monitoring procedures

22
(No Transcript)
23
Using Quality ControlReduces Error Rate
Sample HIV Number ------------Errors---
---------- Ab Reactivity Correct With
QC Without QC p-value Negative 6168
3 19 0.014 Strong 4896
4 3 0.830 Positive
Weak 7021 152 307 0.0067
Positive ---------------------------------------
--------------------------------------------------
--------------------------- Total 18085
159 329 0.0023
(97.37) (2.20) ( 2.90)
Source Model Performance Evaluation Program, CDC
24
Post-Analytic QC Components

• Validation of test results
• Reporting of test results
• Interfacing to Laboratory Information Systems
  (LISs)
• Corrective action plan
• Records maintenance

25
Quality Assurance (QA)

• Staffing / Personnel
• Quality control (QC)
• Proficiency Testing / External Quality Assurance

26
Proficiency Testing or External Quality Assessment

• Central organization sends out challenge
  specimens for testing, laboratories results
  evaluated, laboratories sent scores
• Split specimens exchanged with referral
  laboratories
• Alternative methods

27
External Quality Assurance

• Early warning-system for problems
• Measure of laboratory quality
• Valuable benchmarking tool (standardization and
  traceability)
• Indicator of where to direct improvement efforts
• Monitor of changes in technology and testing
  practices (evaluation component)

28
Activities Linking QA Components

• Assess personnel competencies
• Assess pre-analytic, analytic, and post-analytic
  QC system
• Assess PT/EQA performance
• Implement communication systems for customers and
  staff, and systems for complaints investigations

29
Sources of Laboratory QA Guidance and Information

• World Health Organization (WHO)
• UNAIDS
• International Standards Organization (ISO)
• NCCLS
• CDC RRs
• APHL recommendations
• Professional accrediting organizations
• United States laboratory regulations

30
If even the most conservative estimates of gains
in improved testing quality are used, thousands
of testing mistakes may be prevented yearly by
laboratory quality assurance programs.
31
(No Transcript)