Table 2.

QUADAS-2 Questions for Assessing Risk of Bias in Diagnostic Accuracy Studies*

Domain 1: Patient Selection

Was a consecutive or random sample of patients enrolled? (Yes/No/Unclear)

Was a case-control design avoided? (Yes/No/Unclear)

Did the study avoid inappropriate exclusions? (Yes/No/Unclear)

Could the selection of patients have introduced bias? Risk: Low/High/Unclear

Domain 2: Index Test(s) (complete for each index test used)

Were the index test results interpreted without knowledge of the reference standard? (Yes/No/Unclear)

If a threshold was used, was it pre-specified? (Yes/No/Unclear)

Could the conduct or interpretation of the index test have introduced bias? Risk: Low/High/Unclear

Domain 3: Reference Standard

Is the reference standard likely to correctly classify the target condition? (Yes/No/Unclear)

Were the reference standard results interpreted without knowledge of the results of the index test? (Yes/No/Unclear)

Could the reference standard, its conduct, or its interpretation have introduced bias? Risk: Low/High/Unclear

Domain 4: Flow and Timing

Was there an appropriate interval between index test(s) and reference standard? (Yes/No/Unclear)

Did all patients receive a reference standard? (Yes/No/Unclear)

Did all patients receive the same reference standard? (Yes/No/Unclear)

Were all patients included in the analysis? (Yes/No/Unclear)

Could the patient flow have introduced bias? Risk: Low/High/Unclear

*Questions related to assessing applicability were excluded here. See the original reference for the complete scale¹³