Objectives:

To introduce the different forms of bias that can affect systematic review results, and the methods that can be used to detect and address these biases.

Description:

The results of a systematic review can be distorted if bias has been introduced into the review process at any stage (e.g. biased location and selection of included studies, high risk of bias in the results of included studies). Accordingly, investigation of the presence, degree, and nature of bias is mandatory and is as a routine part of the systematic review process. The Bias Methods Group draws together researchers interested in this field, and the Cochrane Handbook contains chapters on ‘Assessing risk of bias in included studies’ and ‘Addressing reporting biases’. The workshop will largely draw upon the work of members of this Group, of which the facilitators are the co-Convenors. We will discuss potential biases that might be introduced into reviews, with an emphasis on the effects of flaws in the methodology of component studies. We will discuss how review authors should incorporate risk of bias assessments in meta-analyses. The workshop will consist of presentation, discussion and worked examples with and among participants and in small groups.