Experiment 2: Concepts of Quality Control and Safety in Serologic Testing Flashcards
Refers to the overall process of guaranteeing quality patient care and is regulated throughout the total testing system
QUALITY ASSESSMENT or QUALITY ASSURANCE (QA)
are the variables that occur before the actual testing of the specimen
Pre-analytical factors
Pre-analytical factors
• Test request
• Patient preparation
• Specimen collection, handling, and storage
are the processes that directly affect the testing of specimens.
Analytical factors
Analytical factors
• Reagents • Instrumentation and equipment: instrument calibration and maintenance • Testing procedure • Preventive maintenance • Access to procedure manuals • Competency of personnel performing the tests
o Refers to the materials, procedures, and techniques that monitor the accuracy, precision, and reliability of a laboratory test
Quality Control (QC)
are performed to ensure that acceptable standards are met during the process of patient testing
o QC procedures
• Used to verify the accuracy and precision of a test and are exposed to the same conditions as the patient samples.
is the ability to maintain both precision and accuracy
External quality controls
Reliability
(ability to obtain the expected result)
accuracy
(ability to obtain the same result on the same specimen)
precision
consists of internal monitoring systems built into the test system
Internal quality control
controls monitor the correct addition of a patient specimen or reagent, the instruments/reagents interaction, and test completion
• Internal or procedural
monitor a test system’s electronic or electric components
• Electronic controls
• The testing of unknown samples received from an outside agency
Proficiency testing
• It provides unbiased validation of the quality of patient test results
Proficiency testing
are processes that affect the reporting of results and correct interpretation of data.
Post-analytical factors
How close measurement is to true value
o Accuracy
How close results are when same sample is tested multiple times
o Precision
Range of values over which laboratory can verify accuracy of test system
o Reportable range
Formerly called normal value
o Reference interval
Lowest concentration of substance that can be detected by test method
o Analytical sensitivity
Ability of method to measure only analyte it is supposed to measure and not other related substances
o Analytical specificity
• Process of testing and adjusting analyzer’s readout to establish correlation between measured and actual concentrations
o Calibration
• Reference material with known concentration of analyte
o Calibrator
• Testing materials of known concentrations (calibrators, controls, proficiency testing samples, patient specimens with known values) to ensure accuracy of results throughout reportable range
o Calibration verification
• Test three (3) levels: high, midpoint, and low
o Calibration verification
• Required every 6 months, when lot number of reagents changes, following preventive maintenance or repair, and when controls are out of range
o Calibration verification
Positive results in a patient who has the disease
True Positive (TP)
Positive results in a patient who does not have the disease
False Positive (FP)
Negative results in a patient who does not have the disease
True Negative (TN)
Negative results in a patient who has the disease
False Negative (FN)
% of population with the disease that test positive
Diagnostic sensitivity
% of population without the disease that test negative
Diagnostic specificity
