QUADAS-C: a tool for assessing risk of bias in comparative diagnostic accuracy studies

Article type
Authors
Yang B1, Whiting P2, Davenport C3, Deeks J3, Hyde C4, Mallett S3, Takwoingi Y3, Leeflang M1
1Department of Clinical Epidemiology, Biostatistics and Bioinformatics, Amsterdam UMC, University of Amsterdam
2Population Health Sciences, Bristol Medical School
3Test Evaluation Research Group, Institute of Applied Health Research, University of Birmingham
4Exeter Test Group, Institute of Health Research, College of Medicine and Health, University of Exeter
Abstract
Background: Comparative diagnostic test accuracy studies assess the accuracy of multiple tests in the same study and compare their accuracy. While these studies have the potential to yield reliable evidence regarding comparative accuracy, shortcomings in the design, conduct and analysis may bias their results. The currently recommended quality assessment tool for diagnostic accuracy studies, QUADAS-2, is not designed for the assessment of test comparisons.

Objectives: We developed QUADAS-C as an extension to QUADAS-2 to assess the risk of bias in comparative diagnostic test accuracy studies.

Methods: Through a four-round Delphi study involving 24 international experts in test evaluation and a face-to-face consensus meeting, we developed a draft version of QUADAS-C which will undergo piloting in ongoing systematic reviews of comparative diagnostic test accuracy.

Results: QUADAS-C retains the same four-domain structure of QUADAS-2 (patient selection, index test, reference standard, flow and timing) and is comprised of additional questions to each QUADAS-2 domain. A risk of bias judgement for comparative accuracy requires a risk of bias judgement for each test (QUADAS-2), and additional criteria specific for test comparisons. Examples of such additional criteria include whether patients either received all index tests or were randomized to index tests, and whether index tests were interpreted blinded to other index tests.

Conclusions: QUADAS-C will be useful for systematic reviews of diagnostic test accuracy addressing comparative accuracy questions. Furthermore, researchers may use this tool to identify and avoid risk of bias when designing a comparative diagnostic test accuracy study. Currently a draft version of QUADAS-C is being piloted and the tool will be finalized by the time of the conference. This tool was developed together with the QUADAS-C Advisory Group.

Patient or healthcare consumer involvement: Patients or healthcare consumers were not involved in the design and execution of this study.