19.07.14 Internal QC validating new methods Flashcards
Internal quality control
- Activities undertaken to detect, reduce and correct deficiencies in a labs internal analytical process
- Ensures procedures are fit for purpose
What steps are an essential part of IQC
- Validation
- Verification
What is verification
- Confirmation, through provision of objective evidence, that specified requirements have been fulfilled (doing a test correctly)
- Assessing kits/reagents/ software is fit for use
What is validation
Confirmation, through the provision of objective evidence, that the requirements for a specific intended use or application have been fulfilled (doing correct test)
-Includes clinical utility
Steps involved in a validation
- Description of process/equipment being evaluated
- Intended use
- Aims/ objectives
- Defined acceptance criteria
- Evaluation process (sample type etc)
- assessment of uncertainty of measurement
- Record and review outcomes (reproducibility, limits, sensitivity, specificity)
What is ACCE
- Analytical validity
- Clinical validity
- Clinical utility
- Ethical, legal and social implications of genetic testing
What is the purpose of ACCE framework?
Key components of genetic test validation
How many steps is analytical validity
3 steps
1) Pre-analytical (sampling, transportation, labelling)
2) Analytical (preparation of sample and carrying out analysis)
3) Post-analytical (result interpretation and reporting)
Main difference between validation and verification
- Validation is carried out when there is no suitable performance specification available, i.e. a novel test. It defines performance characteristics of a test.
- Verification compares performance characteristics of test with specifications.
What parameters are evaluated during validation/ verification
- Sensitivity
- Specificity
- Accuracy
- Trueness
- Precision
- Repeatability
- Reproducibility
- Robustness
- Limit of detection
- Limit of quantification
What is sensitivity
The proportion of positive results correctly identified by a test
What is specificity
The proportion of negative results correctly identified by a test
What is accuracy
How often a test gives the correct result (positive or negative)
What is trueness
- For quantitative tests, where results can have any value between two limits, this is a measurement of how close the test result is to the reference value.
- Deviation from reference value indicates a systematic error or bias.
What is precision
- Degree to which separate measurements differ
- Can be expressed as the standard deviation of a set of replicate results or the confidence interval around the mean.
What is repeatability
- Closeness of agreement of results obtained when using the same samples under the same test conditions and repeated over a short period of time
- Within-run precision
What is reproducibility
- Closeness of agreement of results obtained when using the sample samples under different test conditions
- Between-run precision
What is robustness
Reliability of test (how well it maintains precision) when certain variables (sample, analyst, reagent, instrument) are changed.
What is the limit of detection
For quantitative tests, where results can have values between two limits, this is the lowest quantity of analyte that can be reliably detected by the test
What is the limit of quantification
The extremity at which accurate quantification can still be achieved.
What is the measurement of uncertainty
Numerical expression of the degree of doubt of the result
What is important to do once a test is validated
-Performance monitoring (ongoing validation, IQC)
