1-Quality Assurance and Quality Control.pdf - Quality...

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Quality Assurance & Quality ControlMLS 4625:Clinical Chemistry I
What makes a good laboratory test?
Quality Assurance ActivitiesAppropriate use of statistics Proper Instrument Calibration Appropriate Quality Control Internal QC External QC (proficiency testing) Identifying analytical and diagnostic utility of an assay Determining reference ranges Assuring staff competency Assessing differences between methods Assessing analytical measuring range (linearity) Documentation: Troubleshooting analytical errors Resolving non-analytical errors Performing Preventative Maint. on instruments
Use of Statistics in the LaboratoryBefore we can talk about quality, we need to remember some basic stats routinely used Stats are used to help assess quality of methods and patient results Statistics routinely used in the clinical lab Mean Standard deviation Coefficient of variation Linear regression and correlation coefficients
MeanThe average value of a set of numbers
Standard Deviation()()SDxxn=21Expresses how disperse the data is from the mean.
Gaussian Curve
Gaussian Curve Std DeviationsResults in a Gaussian curve 68.3% of the results are +/- 1 SD 95.5% +/- 2 SD 99.7% +/- 3 SD
Coefficient of VariationCompares different sets of observations relative to the mean The smaller the CV, the more values that are close to the mean Ideal < 5% for many assays Some you want tighter, some looser
Equation for CV
Regression and CorrelationHelps describe the relationship between two methods Must know how to interpret slope, y-intercept, and Correlation Coefficient
Instrument CalibrationStandards/Calibrators Material has a known value of the given analyte When Performed: Calibrate new instruments Recalibrate after repair Manufacturer’s recommendations Reagent do deteriorate to an acceptable degree Recalibrating accounts for this anticipated deterioration Test method out of control Do NOT jump to this!
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Types of StandardsPrimary Standard Extremely pure substance Tough to come by in the clinical laboratory Secondary Standard Prepared in a laboratory for a specific analysis and compared to a primary standard to assure reference value is correct
Quality ControlPurpose: Ensures patient results are reliable Reliable = accurate and precise results Accuracy How close is the result to the true result?

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