Specificity (SP) and Sensitivity (SN)
We are using Specificity (SP) and Sensitivity (SN) in order to determine clinical utility.
Sensitivity (SN): Measures the proportion of actual positives which are correctly identified as such (eg, the percentage of sick people who are correctly identified as having a condition).
Specificity (SP): Measures the proportion of negatives which are correctly identified (eg, the percentage of healthy people who are correctly identified as not having the condition).
Furthermore are we using +LR and -LR when we combine test: You want the LR+ to be high and the LR- to be low.
- Positive Likelihood ratios (+LR): dictates how much the odds of the disease increase when test is positive.
“is the likelihood that a given test result would be expected in a patient with the target disorder compared to the likelihood that the same result would be expected without the disorder”
- Negative Likelihood ration (-LR): dictates how much the odds of the disease decrease when a test is negative.
DOR (Diagnostic OR) express the strength of association between the test result and disease.
Screen or test?
Test there are recommended for test using specificity >80%, sensitivity >80%, LR+ > 5.0 and LR- ≤ 0.20.