Evidence-appraisal glossary
Verification bias
Verification bias distorts a diagnostic test's accuracy when whether a patient gets the reference (gold-standard) test depends on the index test result. It typically inflates sensitivity and deflates specificity.
Also called: workup bias, referral bias.
Verification bias, also called workup bias, occurs in diagnostic accuracy studies when patients with a positive or suspicious index test are more likely to be confirmed by the gold standard than those with a negative one. The unverified patients are missing in a non-random way, so the measured sensitivity and specificity no longer reflect the full spectrum of tested people. It is a specific structural flaw in study design, not a claim that the test itself is bad.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.