ITEM 11.    Describe whether or not the readers of the index tests and reference standard were blind (masked) to the results of the other test and describe any other clinical information available to the readers.

Example

All images were interpreted on the computer workstation by two radiologists (J.Y., R.K.H.) independently, and subsequently a consensus reading was performed. The radiologists were blinded to the patient’s history, including whether the patient had been recruited for screening or for symptoms, and to results of standard colonoscopy and histologic analysis.[1]

Knowledge of the results of the reference standard can influence the reading of the index test, and vice versa. Such knowledge is likely to increase the agreement between results of the index test and those of the reference standard, leading to inflated measures of diagnostic accuracy. The distortion of measures of diagnostic accuracy caused by knowledge of the result of the reference standard while interpreting the index test is known as test review bias.[2] Knowing the result of the index test while interpreting the reference standard has been named diagnostic review bias.[2] The observation that interpretations become more accurate by providing additional clinical information to interpreters is known as clinical review bias.[3,4,5]

Withholding information from the readers of the test is known as blinding or masking. Readers can be masked for the results of other tests or even for all information related to the patient. Blinding of readers of tests is important. In a meta-regression analysis of a wide range of tests, test review bias produced a moderate exaggeration of measures of diagnostic accuracy.[6] Individual studies have shown a substantial effect of inappropriate masking.[7]

The example shows how the readers of CT colonography for colorectal polyp and cancer detection were blinded to additional clinical information as well as to the results of colonoscopy, the reference standard.

References