Within systematic reviews of diagnostic test accuracy, the QUADAS-C tool can assess risk of bias in test comparisons undertaken in comparative accuracy studies (studies that evaluate two or more index tests). QUADAS-C is an extension of QUADAS-2 (i.e., it is a set of additional questions to each QUADAS-2 domain): meaning that it should be used together with QUADAS-2. Each QUADAS-C domain asks about QUADAS-2 judgments for each test and additional signalling questions that are specific for comparisons (e.g. whether a fully paired or randomized design was used) to produce a risk of bias judgment for the comparison. Like QUADAS-2, QUADAS-C is a generic tool for all systematic reviews of diagnostic test accuracy but can be tailored to a specific review question.
June 2022: Cochrane endorsed QUADAS-C as optional for prospective authors following a recommendation from the Methods Executive, which was informed by the relevant Methods Group, Cochrane's Methods Support Unit, the Head of Methods and Evidence Synthesis/Deputy Editor-in-Chief, a Cochrane Review Group representative and the Methods Executive representative on Cochrane's Editorial Board.
- Cochrane Handbook for Systematic Reviews of Diagnostic Test Accuracy chapter on assessing risk of bias and applicability.
- QUADAS-C official tool webpage, which includes:
- Full guidance on how to use QUADAS-C.
- A tool to complete the assessments (we recommend these are hosted in a repository for quality assessment, peer review and to complement the published review).
- Template for graphical displays of QUADAS-C assessments (for use as figures in the review).
- Template for tabular displays of QUADAS-C assessments (for use as tables in the review).
- QUADAS-C: A Tool for Assessing Risk of Bias in Comparative Diagnostic Accuracy Studies published article in Annals of Internal Medicine.
- Screening and Diagnostic Tests Methods Group website.