Quality Control/ Quality Assurance Flashcards
- It is a system of ensuring accuracy and precision in the laboratory by including quality control reagents in every series of measurements
Quality Control
It is a process of ensuring that analytical results are correct by testing known sample in resemble patient sample
Quality Control
It is the ability of an analytical method to measure the smallest concentration of the analyte interest
Sensitivity
It is the ability of analytical method to measure only the analyte of interest
Specificity
It is the ability of an analytical method to maintain accuracy and precision over an extended period of time during which equipment
Realibility
It is an ability of an analytical method to detect the proportion of individual without the disease
Diagnostic specificity
It is an ability of an analytical method to detect the proportion of individual with the disease
Diagnostic sensitivity
Require high sensitivity so that no case is missed
Screening test
Require high specificity to be certain of the diagnosis
Confirmatory test
It involves the analyses control samples together with the patient specimen; detects both random and systematic error in a daily basis
Internal QC
It is important in maintaining long term accuracy of the analytical method
External QC
The gold standard for clinical elab external QC testing
College of American Pathologist
To ensure clinicians that patient results are accurate
Proficiency testing
Objectives of quality control
- To check the stability of the machine
- To check the quality of reagents
- To check technical operator errors
The accuracy of any assay depends on ____
Control solutions (QC materials)
General chemistry assay used ___ of control solutions
2 levels
Immuno assay used ___ of control solutions
3 levels
___ are calculated from mean and SD
Control limits
Ideal control limits is between ___
+/- 2 SD
Characteristics of an Ideal QC material
- Resembles human sample
-Inexpensive and stable for long period - No communicable disease
- with known analyte concentration
Present in all measurements; type of error that varies from sample to sample; Known as imprecision
Random Error
Error that influences observation consistently in one direction; known as inaccuracy
Systematic error
Pre analytical error
- incorrect patient identification
-improper patient preparation - mislabeled spicemen
- incorrect order of draw
Analytical Error (During)
- incorrect sample and reagent volume
- incorrect incubation of solutions and timing
- equipment malfunction
Post analytical error
- unavailable or delayed lab results
- long TAT
- incomplete lab result
Is a measured central tendency; average
Mean
It is a measured of dispersion of values from the mean; most frequently used measure of variation
Standard Deviation
Percentile expression of the mean; measure of random error
Coefficient of variation
The standard deviation squared; measures variability; represent the difference between each value and the average of the data
Variance
Used to determine whether there is a statistically significant difference between the SD of 2 groups of data
F test
Used to determine whether there is a statistically significant difference between the means of the two groups of data
T test
Used to observe values of control materials over time to determine reliability of the analytical method
Quality Control Chart
Occurs when the data set can be accurate, it describe by the SD and the mean; centered around the mean with most elements close to the mean
Gaussian curve( bell shaped curve)
Calculate the difference between QC results an the target means; common method : V-mask
Cumulative sum graph (CUSUM)
It is used to compare results obtained on a high and low control serum from different labs
Youden/ twin plot
Most widely used QC chart in the clinical lab; easily identifies random and systematic errors
Shewart levey Jenning chart
Formed by control values that either increase or decrease for six consecutive days
Trend
Formed by control value that distribute themselves on one side or either side of the mean for six consecutive days
Shift
These are control values that are far from the main set values; highly deviating values
Outliers
Can increase without increasing the false rejection rate
Westgard control chart
Indicate if the analytical process is out of control
Control rule
