QUADAS-2

QUADAS-2 (PDF, 265kB) is the current version of QUADAS and the tool that we recommend for use in systematic reviews to evaluate the risk of bias and applicability of primary diagnostic accuracy studies. QUADAS-2, consists of four key domains:

Each is assessed in terms of risk of bias and the first three in terms of concerns regarding applicability. Signalling questions are included to assist in judgements about risk of bias. QUADAS-2 is applied in four phases:

  1. summarise the review question
  2. tailor the tool to the review and produce review-specific guidance
  3. construct a flow diagram for the primary study
  4. assess risk of bias and concerns regarding applicability

Download background document (PDF, 548kB)

Risk of bias and applicability judgments

The following table summarises QUADAS-2 and lists all signalling, risk of bias and applicability rating questions.

DOMAINPATIENT SELECTION  INDEX TEST REFERENCE STANDARDFLOW AND TIMING 
Description Describe methods of patient selection: Describe included patients (prior testing, presentation, intended use of index test and setting):  Describe the index test and how it was conducted and interpreted:  Describe the reference standard and how it was conducted and interpreted:  Describe any patients who did not receive the index test(s) and/or reference standard or who were excluded from the 2x2 table (refer to flow diagram): Describe the time interval and any interventions between index test(s) and reference standard:
Signalling questions(yes/no/unclear) Was a consecutive or random sample of patients enrolled? Were the index test results interpreted without knowledge of the results of the reference standard? Is the reference standard likely to correctly classify the target condition? Was there an appropriate interval between index test(s) and reference standard?
Was a case-control design avoided? If a threshold was used, was it pre-specified? Were the reference standard results interpreted without knowledge of the results of the index test? Did all patients receive a reference standard?
Did the study avoid inappropriate exclusions? Did all patients receive the same reference standard?
Were all patients included in the analysis?
Risk of bias: High/low/unclear Could the selection of patients have introduced bias? Could the conduct or interpretation of the index test have introduced bias?       Could the reference standard, its conduct, or its interpretation have introduced bias? Could the patient flow have introduced bias? 
Concerns regarding applicability: High/low/unclear Are there concerns that the included patients do not match the review question? Are there concerns that the index test, its conduct, or interpretation differ from the review question? Are there concerns that the target condition as defined by the reference standard does not match the review question?