Quality Control Flashcards
What is Quality Control?
A way to ensure that the results reported are accurate
Can be qualitative or quantitative.
What is qualitative Quality Control?
Includes positive/negative agglutination, desired stain outcomes, and growth/no growth
Examples include Stains giving desired outcomes.
What is quantitative Quality Control?
Numerical result matches expected value
Focused mainly in Chemistry and Hematology due to automation.
Define accuracy in Quality Control.
Nearness to true value
Define precision in Quality Control.
Reproducibility or closeness of repeated results to each other
What does a Bulls eye analogy represent in Quality Control?
Accuracy and precision; closer points to the center indicate more accuracy, while closer points to each other indicate more precision.
What are the examples of Quality Control per department?
- Chemistry: 20+ analytes (glucose to cholesterol)
- Hematology: coagulation, CBC, ESR
- Microbiology: media to stains (gram)
- Histology: stains
- Transfusion: reagents for typing/phenotyping
What is a frequency distribution histogram?
A graphical representation of the frequency of values obtained from repeated analysis.
What is Gaussian distribution?
A symmetrical distribution around a central point
Also referred to as normal distribution.
What is standard deviation (SD)?
Describes the spread of values around the mean and reflects the distance of values from the mean.
What is the coefficient of variation (%CV)?
Standard deviation expressed as a percentage of the mean; indicates precision of a method.
What is the rounding rule for the last digit to be dropped if it is less than 5?
Leave the preceding number unchanged.
What is the rounding rule for the last digit to be dropped if it is greater than 5?
Increase the preceding figure by 1.
What is the rounding rule for the last digit to be dropped if it is exactly 5?
If the preceding figure is odd, increase by 1; if even, leave it.
What percentage of data falls within +1 SD in a Gaussian distribution?
68%
What percentage of data falls within +2 SD in a Gaussian distribution?
95.5%
What percentage of data falls within +3 SD in a Gaussian distribution?
99.7%
What information must be included on a Levey-Jennings chart?
- Mean
- SD
- CV
- 3-4 standard deviations
- Analyte name
- Instrument/method identification
- QC level with lot# and expiration date
- Calibrator and reagent lot #
- Date for each data point
- Record of intervention actions
- Identification of MLT assessing control
How long should quality control typically be run in Chemistry?
Usually in a period not less than 10 days.
What is the optimal number of data points for new QC materials?
20 points.
What are the characteristics of quality control?
- Systematic monitoring of analytic processes
- Detection of analytic errors
- Assaying stable control materials
- Comparison to expected values
What is the definition of ‘in-control’ values in Quality Control?
Values within the upper and lower limit.
What should be done when values are out of control?
Halt patient testing and investigate the problem.
What are QC materials?
Specimens analyzed for QC, known for stability and same matrix as specimen being tested.
