Disease Screening Populations

What does the table for evaluating a screening test look like?

Describe the following terms:

• True Positive

• False Positive

• True Negative

• False Negative

• True positive = High risk + affected

• False positive = High risk + unaffected

• True negative = Low risk + unaffected

• False negative = Low risk + affected

How is specificity calculated?

Low risk unaffected / Total unaffected

How is sensitivity calculated

High risk affected / Total Affected

How is PPV calculated?

High risk affected / Total high risk

How is NPV calculated?

Low risk affected / Total low risk

What does a filled in evaluation table look like?

How to calculate the incidence rate?

Total Affected / Total population

False Negative Rate

Low Risk Affected / Total Affected

False Positive Rate

High risk Unaffected / Total Unaffected