Table 1 Potential outcomes of screening tests with varying levels of sensitivity and specificity

Impact on results

↑ True positives

↑ True negatives

Testing goal

Identify people with disease

Identify people without disease

Treatment goal

· Treat disease

· Avoid unnecessary treatment

· Prevent future illness and, in the case of infection, possible disease spread

Potential harms of opposite test characteristic

Low sensitivity:

Low specificity:

· ↑ False negatives

· ↑ False positives

· ↑ Potential future illness and suffering

· ↑ Bodily harms, toxicity, and financial costs of unnecessary treatment

· ↑ Potential future spread of disease (in the case of infection)

· ↑ Social stigmatization

· ↓ confidence in screening program