Risk of bias reporting in Cochrane systematic reviews


  • Lisa Hopp PhD RN FAAN

    Director, Professor, Corresponding author
    1. Indiana Center for Evidence Based Nursing Practice: A Joanna Briggs Collaborating Center, Hammond, Indiana, USA
    2. College of Nursing, Purdue University Calumet, Hammond, Indiana, USA
    • Correspondence: Lisa Hopp, College of Nursing, Purdue University Calumet, 2200 169th St, Hammond, IN 46323, USA. Email: ljhopp@purduecal.edu

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Risk of bias is an inherent quality of primary research and therefore of systematic reviews. This column addresses the Cochrane Collaboration's approach to assessing, risks of bias, the meaning of each, indicators of low, high and uncertain, and ways that risk of bias can be represented in a Cochrane systematic review report. The sources of risk of bias that reviewers evaluate include selection, performance, detection, attrition and reporting bias. Each poses threat to the internal validity of the primary studies and requires the reviewer to judge the level of risk as high, low or unclear. Reviewers need to address how studies of higher risk of bias might impact the pooled effect.