Assessment of risk of bias in comparative diagnostic accuracy systematic reviews: an overview of reviews

Article type
Authors
Yang B1, Vali Y1, Sharifabadi A2, Harris I3, Beese S3, Davenport C3, Hyde C4, Takwoingi Y3, Whiting P5, Langendam M1, Leeflang M1
1Amsterdam UMC
2University of Ottawa
3University of Birmingham
4University of Exeter
5University of Bristol
Abstract
Background: comparative diagnostic test accuracy (DTA) systematic reviews assess the accuracy of two or more tests to compare the diagnostic performance of the tests. The 'Risk of bias' assessment should also consider the validity of the test comparison but it is unclear how this should be done.

Objectives: to investigate whether and how recent comparative DTA reviews assessed the risk of bias in test comparisons.

Methods: we searched for comparative DTA reviews indexed in MEDLINE from 1 January to 31 December 2017. Two authors independently identified DTA systematic reviews including at least two index tests and containing at least one statement in which the accuracy of the index tests was compared. Two authors extracted data on review characteristics and methods used to assess risk of bias. We discerned two types of test comparisons: within-study comparisons (comparison of tests within a single study) and between-study comparisons (comparison of tests each evaluated in different studies).

Results: we included 234 comparative DTA reviews. The majority (83.3%) evaluated imaging or biochemical tests. One review assessed risk of bias of within-study comparisons, and none of the reviews assessed risk of bias of between-study comparisons. Restricting our analysis to reviews that explicitly planned to compare tests did not change our results. None of the included reviews used a 'risk of bias' tool specifically designed to assess bias in the test comparison.

Conclusions: assessment of risk of bias in test comparisons is uncommon in comparative DTA reviews, possibly due to lack of existing guidance and awareness of potential sources of bias. Based on our findings, guidance on how to assess and incorporate risk of bias in comparative DTA reviews is needed.

Patient or healthcare consumer involvement: patients or healthcare consumers were not involved in this study.