Assessing bias due to confounding in a Cochrane systematic review which includes non-randomised studies of an intervention (NRSI)

1 - 2:30pm


The workshop aims to train review authors to assess the risk of bias due to confounding, using an extended risk of bias tool (ACROBAT-NRSI), when including NRSI in a systematic review about the effects of an intervention.


Cochrane recommends that review authors consider and justify whether or not to include NRSI for all research questions about the effects of interventions. Decisions to include NRSI may arise when there are inadequate or no RCTs but where the question addressed by the review is a considered a priority. Topics about possible harmful or long term effects of interventions, or review questions about the effects of public health and non-pharmacological interventions, may have these characteristics. This workshop aims to give review authors and others intending to include NRSI in Cochrane systematic reviews experience in applying ACROBAT-NRSI (an extended risk of bias tool for this situation). Participants will mainly work in small groups to apply the ‘signalling questions’ for the confounding domain of the tool, a domain which does not apply to RCTs. Signalling questions prompt the user to assess key aspects of studies and then to judge whether the finding from a study for a particular review outcome is at high or low risk of material bias in the domain. Responses to signalling questions and domain specific bias judgements are made on four-point scales and include a ‘no information’ option; these features will be contrasted with the existing risk of bias tool.

Target audience

Review authors intending to include non-randomised studies of an intervention (NRSI) in a Cochrane systematic review of the effects of an intervention and editors involved with such reviews.


Barney Reeves; Jelena Savovic


Beverley Shea, Julian Higgins, Jonathan Sterne, George Wells

Barney Reeves

Jelena Savovic