What is the difference between a screening test and a diagnostic test?

• A. Screening is used to confirm disease after symptoms appear.
• B. Diagnostic testing identifies risk in asymptomatic people.
• C. Screening identifies risk in asymptomatic people; diagnostic testing confirms disease after a positive screen.
• D. Screening results always provide a definitive diagnosis.

Answer: (C)

Screening tests are used in people without symptoms to flag individuals who may be at higher risk for a disease, so they can undergo follow-up diagnostic testing to determine if the disease is actually present. Diagnostic tests are then used to confirm whether the disease exists after a positive screen or when symptoms prompt evaluation.

This is why the correct statement describes screening as identifying risk in asymptomatic people and diagnostic testing as confirming disease after a positive screen. The other descriptions are off because screening is not for confirmation after symptoms, diagnostic testing is not about identifying risk in asymptomatic people, and screening results are not always definitive without a confirmatory diagnostic test.