Verification bias

Verification Bias

Verification bias, also known as workup bias, is a type of bias that occurs in diagnostic test evaluations. It arises when the results of a diagnostic test influence whether further verification or confirmation of the diagnosis is pursued. This can lead to an overestimation or underestimation of the test's accuracy.

Causes

Verification bias typically occurs in clinical studies where not all patients undergo the same reference standard test. For example, if only patients with positive test results are subjected to a gold standard test, while those with negative results are not, the accuracy of the test may be skewed.

Effects

The primary effect of verification bias is the distortion of the sensitivity and specificity of a diagnostic test. Sensitivity may be overestimated if only positive test results are verified, while specificity may be underestimated if negative results are not confirmed.

Mitigation Strategies

To mitigate verification bias, researchers can employ several strategies:

• Blinded Assessment: Ensuring that the decision to perform the reference standard test is made independently of the initial test results.
• Random Verification: Randomly selecting a subset of both positive and negative test results for verification.
• Complete Verification: Applying the reference standard test to all subjects, regardless of the initial test outcome.

Related Concepts

• Selection bias
• Spectrum bias
• Observer bias

Conclusion

Verification bias is a significant concern in the evaluation of diagnostic tests. Understanding and addressing this bias is crucial for ensuring the reliability and validity of test results in clinical practice.