Adherence to quality control protocol is common in clinical laboratory testing. However, in the arena of worksite biometric screening there are misconceptions and general misunderstanding.
Biometric screeners are often asked how often they calibrate testing instrumentation. The fact is that point of care testing instruments are “calibrated” by the manufacturer. A calibration curve is used to determine the instrument response to a change in the concentration of the analyte (substance to be measured). Medical devices for blood testing, blood pressure devices and even scales are not “calibrated” by the end user.
The correct question is “how often does the screener verify device calibration”. The difference is more than semantics.
Calibration Verification for devices analyzing blood samples is done by running samples of known concentration on the system. This will assure that the device is accurately measuring samples throughout the reportable range. This should be done every 6 months for each analyzer.
Quality Control (QC) for blood testing devices includes an “optics check” and testing QC material. The “optics check” should be run before any screening activity. This will confirm that the analyzer is operating according to manufacturer specifications. QC material has a target range for each measured analyte (test). Typically there are two levels of QC performed (normal and abnormal). QC on both levels should be performed onsite before any testing event. Successful measurement of both levels demonstrates that the reagents (testing materials) are functioning according to manufacturer specifications.
Quality Assurance is a management plan designed to provide oversight and measurement of the overall delivery system. The successful Quality Assurance program for biometric services will guarantee the integrity of all deliverables including accuracy of testing, reporting, data security, client services and participant interaction.
Proficiency Testing programs can be mandated by regulatory agencies or voluntary. In these programs participant laboratories receive test materials for testing. The submitted results are evaluated and compared with known values. The performance of the laboratory testing is evaluated and compared against other program participants.
Accuracy versus Precision is an important concept in biometric testing. Accuracy is determined by how well a measurement agrees with the actual value. Precision is determined by how well a series of measurements agree with each other. Therefore it is possible to have precision without accuracy. A sound biometric program will deliver accurate results which are reproducible.
Familiarity with these terms and concepts will facilitate the process of selecting a biometric vendor.