Quality management, QA, QC Flashcards
What is ‘quality control’/QC?
Quality Control/QC:
Evidence that, on that day for that specific run, an analytical procedure was performed correctly.
What is ‘quality assurance’/QA?
Quality assurance/QA:
Longitudinal studies showing that things are working as expected for “planned periodic activities”
OR
Planned periodic activities to provide confidence that things are working as expected.
E.g. tracking disk diffusion zone sizes for QC strains over time to track any drift in performance.
What is a ‘quality management system’ (QMS)?
“Quality Management System” (QMS)
A systematic method to manage a lab and meet quality objectives
OR
ensure that quality is planned, documented, reviewed, and continually sought.
What are the 3 themes of QMS’s?
Infrastructure
E.g. personnel, facilities, inventory
Operations
E.g. documents, process managment
System assessment
E.g. NCE management, continual improvement
What are the quality system essentials under the theme Infrastructure?
- Organization
- Customer focus
- Personnel
- Facilities & safety
- Purchasing & inventory
What are the CLSI quality system essentials under the theme Operations?
- Documents & records
- Equipment
- Process management
- Information management
What are the CLSI quality system essentials under the theme System assessment & improvement?
- Assessments
- NCE management
- Continual improvement
What is the difference between an assay ‘validation’ vs. ‘verification’?
Validation:
Establishing the performance traits of a test/procedure, to show that the test:
- meets the required performance criteria;
- is accurate & reliable.
Verification:
Confirming the specifications claimed by the method manufacturer.
OR
Confirming that a test performs as expected & meets all required criteria (when used exactly as it was validated)
(Both || are part of a QMS, within the QSE ‘Process Management’)
How do you conduct an assay verification?
(This means to confirm that the protocol works as intended in the lab’s hands)
Utilize representative positive and negative clinical specimens (and controls) to determine the assay’s:
- Agreement (with a reference method)
- Analytical Sn + Sp
- Precision || (for quant) or reproducibility || (for qual)
- Bias/trueness
How do you conduct an assay validation?
Same as for verification, and:
Consider:
- Assess performance in different samples types, collection media, and other variables that could affect the test’s performance.
- Risk management to reduce lab errors
As for verifications, determine:
- Analytical Sn + Sp
- Diagnostic Sn + Sp
- Measuring interval
- Reference interval
- Reagent & sample stability
- Precision
- Bias/trueness
What is sensitivity? (Sn)
How do you determine an assay’s sensitivity?
For a qualitative assay,
Analytical Sn: The ability of a test to detect very low levels of an analyte.
HOW: # TP / # of specimens that are truly positive
(i.e. TP / (TP+FN)
For a quantitative assay,
Analytical Sn = LOD.
LOD: The amount of substance in a spx that can accurately be measured by an assay.
HOW: Use multiple specimens across several dilutions across the linear range of detection (usu 10 ea.) –> do a linear regression to determine the LOD.
(Note, if this is outside of the linear range then your result will be “detected” up until the beginning of the linear range – then you can report numbers.)
Diagnostic Sn = % of persons who have a given disorder who are identified by the assay as +ve for the disorder.
What is specificity? (Sp)
How do you determine an assay’s specificity?
Analytical Sp: The ability of a test to detect only the analyte it was designed to measure.
HOW: # TN / # of specimens that are truly negative
i.e. TN / (TN+FP)
What is a POS predictive value?
How do you determine the PPV of an assay?
The probability that a positive test result accurately indicates the presence of an analyte.
i. e. TP/all+
a. k.a. TP / (TP+FP)
What is a NEG predictive value?
How do you determine NPV of an assay?
The probability that a negative test result accurately indicates the absence of an analyte.
i. e. TN/all-
a. k.a. TN / (TN+FN)
