4 Quality Analytical Methods Flashcards
What are the 5 steps process to establish a new analytical method/ changes?
- Selection
- Evaluation
- Implementation
- Maintenance
- QC
In method selection/ design study, what are the 3 factors to consider? (MAP)
- Methodology What analyte does the method test for?, How does the test compare to the current method?
- Application What is the cost?, Will it meet lab TAT?
- Performance How precise/ accurate will results be?, How sensitive is the method?
In method evaluation/ method validation, what does the lab have to do when receiving a new instrument/ method from a manufacturer?
A lab must prove the method is acceptable for use by verifying that the method meets the manufacturer’s claims
What is the purpose of method evaluation/ method validation?
To perform error assessment
In method evaluation/ method validation, what do end users need to verify?
End users need to verify the criteria are being met for their specific patient population
What is error assessment?
Error assessment is making sure that the errors are small enough so that not a big change will be made to the test result/ patient care
To be eligible for medical decision making, what are the 2 criteria lab testing must meet?
Regulatory and scientific criteria
Who sets target ranges for total allowable error (TEa) in clinical chemistry tests?
The Clinical Laboratory Improvement Amendments (CLIA)
True or false - total allowable error (TEa) is always bigger than total error (TE)
True
What are the 3 steps in evaluation? (FSVA)
- Familiarization
- Determining stability of calibrators, controls and reagents
- Perform verification assessment validate/ proof manufacture’s method
What happens in Implementation?
The procedure for the method is being written out, the method is put into routine use, QC procedure is put in place to monitor the method, sources of problems/ preventative maintenance procedures gets done
Why is Maintenance of Equipment and Instrument / Quality Control necessary?
Periodic maintenance gets done on the instruments and Quality Control is necessary to ensure high quality test results
Define the error and what it cause: Random error
Is unpredictable error (data points are up and down) and causes imprecision
Define the error and what it cause: Systematic error
Shifts data/ data trends in one direction and causes inaccuracy
Define the error and what it cause: Constant error
Systematic error will stay the same even if analyte concentration changes. It causes inaccuracy
Define the error and what it cause: Proportional error
Systematic error changes as concentration of analyte changes. It causes inaccuracy
How do we calculate Total Error?
TE = SE + RE
Define allowable total error
Is error undetected during evaluation but the error has to be established before method evaluation
In terms of error, when is method performance ok?
When total error is less than allowable total error
In verification assessment, how do we check the reportable range of method?
By determining linearity. This is done by analyzing the analyte of interest in increasing concentration
In verification assessment, what are the 3 ways to measure accuracy?
- Method comparison - evaluate a new method against a reference method - difficult to do
- Side by side comparison - run 40 specimen using both method and then compare the results with statistical calculations
- Clinical correlation - *Test results should match patients’ diagnosis, clinical symptoms or other lab tests**
In verification assessment, what are the 2 ways to check for precision?
- Within run replication - *three samples are run at least 10 times in the same run and should give same results - intra-assay
- Between run replication - at least three samples run at least 10 times on different days and should give same results - inter-assay
In verification assessment, how do we check for analytical sensitivity?
Minimum limit detection - *use low level of analyte to determine the lowest measurable concentration
In verification assessment, what are the 2 ways to check for analytic specificity?
1, Interfering substances
2. Cross-reactivity
