Accuracy
How accurate a test is to give the correct concentration
- analytical, not clinical
Precision
Same distance/measurement every time
- could still use if you know systematic error
Analytical imprecision
Cannot predict what the error is (random)
- is present in all tests
- large random error will render test nonuseful
Analytical specificity
Could measure something not intended, so there is little specificity
- ex: when hemolysis impacts the results of a test
Detection limit
Would rather have a lower upper detection limit, than too low a minimum detection limit
- easier to dilute a sample than to concentrate it
Which 2 characteristics have little to no systematic error?
Analytical and precision accuracy
Interpretation of results is dependent on ________
Reference range
How are reference intervals established and what do they indicate?
- 60-120 animals of each species
- young adults, clinically healthy, represent animal population of the region
Confidence interval
95% for the population
- 1 in every 20 animals will have a result that is outside the reference interval (even though the animal is healthy)
Reference limit
Value of a test that is above or below the reference limit may indicate pathological state
Decision threshold
Value of a test that is used to classify as positive or negative for a disease, or used to decide changes in treatments
Quality of laboratory results depends on:
- quality of sample
- quality of analysis
- quality of laboratory records
What are the 3 components of quality assurance?
- preanalytical errors (quality of sample)
- analytical errors (quality of analysis)
- postanalytical errors (quality of lab records)
Sample collection
Preanalytical error
- prep of patient
- collection technique
- collection container
- anticoagulant
- sample volume
Sample handling
Preanalytical error
- proper labeling
- appropriate temp
- prompt processing
Analytical error
- method appropriate for species
- quality of instruments and equipment
- quality of reagents
- quality of lab technique
- quality control program (assessment of variations on results)
Postanalytical errors
- transcriptional errors
- graphic quality of report
In-house lab: advantages
- 24hr access
- short turn around time
- fresh sample
In-hoes lab: disadvantages
- cost
- maintaining inventory
- training of personal
- quality assurance program
- reference intervals
Vet reference laboratory: advantages
- personnel trained
- diagnostic support available
- appropriate reference interval
- more tests available
- cost per sample clear
Vet reference lab: disadvantages
- sample may deteriorate
- turn around time is variable
Human lab: advantages
Short turn around time
Human lab: disadvantages
- reference interval may not be established
- assay methods may not be appropriate
- personnel may not know species variations
- price
