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

Tags: Workshop
Shea B1, Reeves B2, Wells G3
1bshea@ohri.ca, 2Bristol Royal Infirmary, UK, 3University of Ottawa, Canada

Objective: To train review authors to assess risk of bias (RoB) due to confounding, using an extended RoB tool (ROBINS-I), when including non-randomized studies of an intervention (NRSI) in a systematic review (SR) about the effects of an intervention.

Description: 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 SRs experience in applying ROBINS-I (an extended risk of bias tool for this situation).

Participants will 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 users to assess key aspects of studies and 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 with a ‘no information’ option; these features will be contrasted with the existing RoB tool.