RoB 2 tool

A revised Cochrane risk of bias tool for randomized trials

A revised tool to assess risk of bias in randomized trials (RoB 2)

Welcome to the website for the RoB 2 tool.

The current version (22 August 2019), suitable for individually-randomized, parallel-group trials.

NEW! A test version for cluster-randomized trials is now available (10 November 2020, revised 18 March 2021).

NEW! A test version for crossover trials is now available (8 December 2020, revised 18 March 2021).

We are also maintaining an archive of the previous version, which had variants for three different trial designs (see below).

Citing the tool

The revised tool may be cited as:

Sterne JAC, Savović J, Page MJ, Elbers RG, Blencowe NS, Boutron I, Cates CJ, Cheng H-Y, Corbett MS, Eldridge SM, Hernán MA, Hopewell S, Hróbjartsson A, Junqueira DR, Jüni P, Kirkham JJ, Lasserson T, Li T, McAleenan A, Reeves BC, Shepperd S, Shrier I, Stewart LA, Tilling K, White IR, Whiting PF, Higgins JPT. RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ 2019; 366: l4898.

Other publications

Higgins JPT, Sterne JAC, Savović J, Page MJ, Hróbjartsson A, Boutron I, Reeves B, Eldridge S. A revised tool for assessing risk of bias in randomized trials In: Chandler J, McKenzie J, Boutron I, Welch V (editors). Cochrane Methods. Cochrane Database of Systematic Reviews 2016, Issue 10 (Suppl 1). dx.doi.org/10.1002/14651858.CD201601.

This work was supported by the MRC Network of Hubs for Trials Methodology Research (MR/L004933/1- N61). Infrastructure support was provided by the Medical Research Council ConDuCT-II Hub (Collaboration and innovation for Difficult and Complex randomized controlled Trials In Invasive procedures – MR/K025643/1).

Archived: Cluster randomized trials (parallel groups)

Note that a revised version for cluster-randomized trials is now available and should be used in preference to this archived version.

Available (old archived version):

  • Background information and detailed guidance for using the RoB 2.0 tool for cluster-randomized trials

  • The tool (cluster-randomized trials) itself

  • Blank template for completing the tool, which is currently available in one version

    • Implement RoB 2.0 for cluster-randomized trials when interest is in the effect of assignment to intervention

Archived: Crossover trials (individually randomized)

Note that a revised version for crossover trials is now available and should be used in preference to this archived version.

Available (old archived version):

  • Background information and detailed guidance for using the RoB 2.0 tool for cross-over trials

  • The tool (cross-over trials) itself

  • Blank template for completing the tool, which has two variants

    • Implement RoB 2.0 for cross-over trials when interest is in the effect of assignment to intervention

    • Implement RoB 2.0 for cross-over trials when the interest is in the effect of starting and adhering to intervention

  • Excel implementation of the tool (cross-over trials) (contains macros)

Archived: individually-randomized, parallel group trials (20 October 2016)

Available:

  • Background information and detailed guidance for using the RoB 2.0 tool.

  • The tool itself

  • Blank template for completing the tool

    • Implement RoB 2.0 when interest is in the effect of assignment to intervention

    • Implement RoB 2.0 when interest is in the effect of starting and adhering to intervention

  • Excel implementation of the tool (cross-over trials) (contains macros)

View videos: RoB 2.0 tool Part 1, RoB 2.0 tool Part 2, RoB 2.0 tool Part 3, RoB 2.0 tool Part 4.