Sample Testing Flashcards
Testing process steps
- Receipt of sample
- Analysis
- Validation
- Interpretation
- Authorisation
- Reporting
Turnaround time
The time taken between receipt and reporting of a sample
Reasons for testing
- To make a diagnosis
- To identify causes of disease
- To monitor disease progress
- To estimate prognosis
- Determine treatment options
- Monitor efficacy of treatment
Sensitivity of a test
The percentage of people with the disease who have a positive result
TP/[TP+FN] X100
Specificity of a test
The percentage of healthy people who have a negative result
TN/[TN+FP] X100
Positive predictive value
The percentage of positive results that are true positives
TP/[TP+FP] X100
Negative predictive value
The percentage of negative results that are true negatives
TN/[TN+FN] X100
Overall efficiency of a test
[TP + TN] X 100 / Total no. of tests
Sources of error
- Pre-analytical (sample collection)
- Analytical (lab errors)
- Post-analytical (calculation/reporting errors)
Point of care testing
POCT can be carried out at a range of locations, including at home or in hospital
POCT gives rapid results but they are less subject to validation steps