Classifying non-randomised studies (NRS) and assessing the risk of bias for a systematic review

Shea B1, Wells G2
1CIETcanada, Canada, 2Univeristy of Ottawa, Canada


The workshop aims to improve awareness of the key issues when including non-randomised studies (NRS) in systematic reviews of effectiveness.


This workshop is aimed at review authors and editors who are considering whether or not to include NRS in reviews to estimate the benefits of an intervention. This situation may arise when there are no RCTs, only poor RCTs or very few small RCTs, but where the question addressed by the review is a priority. Evaluations of public health, practitioner-dependent or device-based interventions may have these limitations. Participants will mainly work in small groups to apply tools developed by the NRSMG to a single NRS. First, participants will classify the NRS with respect to study features (likely to be relevant to setting review eligibility criteria) that the NRSMG recommends extracting from primary studies. Second, participants will assess the risk of bias in the NRS using an extended risk-of-bias tool. The implications of varying amounts and quality of information from primary NRS for systematic reviews of NRS will be discussed. Varying amounts and quality of information is also the norm for systematic reviews of RCTs, so the discussion will contrast the implications for systematic reviews of NRS and RCTs.