Accuracy, reliability, and timeliness. Lab results must be accurate as possible.
What is quality assurance?
QA in the lab is all the things we do to ensure quality results.
ISO Document that applies to the medical Lab is ISO 15189
The Lab:
Organization, Customer Focus, Facilities and safety, Personnel, Purchasing and Inventory, Equipment.
The Work:
Process Management, Documents and records, Information management.
Performance:
Nonconformance Management, Assessments, Continual Improvement. (Reflecting on self performance).
Pre-analytic
Test order, sample collection, transport, receipt and process
Analytic
Testing
Post-analytic
reporting, sample archiving
Sensitivity
Measures low amount of component, few false negatives if high sensitivity, Positive controls in low amounts.
Specificity
Specific- measures one component only, no false positives, uses negative controls.
Report sent to wrong location
Post-analytical
QC not within range
Analytical
Mislabeled specimen
Pre-analytical
CV= SD/ Mean divided by 100
Always to 1 decimal place and in percent
Precision
reproducibility of a result. Ex hitting the same spot on the target.
Accuracy
The correctness. Ex. hitting the center of the target.
Systemic error
Change in accuracy, affect all results until the error is fixed.
Random error
Change in precision, no prediction, one off.
Population
large body of data- should be random and represent any part of the population.
Calibrator
Similar to standard, has more than one analyte, used to correct analytical procedure.
Standard
A solution having known concentration of a single analyte.
Control
A solution that contains the same constituents as those being analyzed in the patient sample. Used to test if our analytical system is giving accurate results or not.
The lower the CV the more precise.
Acceptable CV
Manual methods= less than or equal to 10.0%
Instrumental methods= less than 3.0%
Normal Distribution
1SD- 68%
2SD- 95%
3SD- 99.7%
Reference Range
Range of results for clinically healthy people.
Control range
The acceptable range of a known control sample for an analyte in order to monitor the precision and accuracy of our analytical system.
New lot # means calibration time
Quantitative analysis
The control is a sample that has known values. Used for accuracy and precision.
Qualitative analysis
Provide positive vs negative or reactive vs non-reactive. Known as screening tests- Ex. covid or pregnancy test.
1 in 20 control values may fall outside of the 2SD range.
Trend
Gradual loss of reliability. Usually subtle. Deterioration.
Shift
Abrupt change, a sudden or dramatic positive or negative change.
Always run QC after calibration
Linearity range
If a sample is above linearity range or too high to be run on the analyzer, it can be diluted.
Linearity (dynamic range)
The limit of what the analyzer can detect on a test.