title: Checklists of methodological issues for review authors to consider when including non-randomized studies in systematic reviews.
abstract: BACKGROUND
  There is increasing interest from review authors about including non-randomized studies (NRS) in their systematic reviews of health care interventions. This series from the Ottawa Non-Randomized Studies Workshop consists of six papers identifying methodological issues when doing this.
  
  
  OBJECTIVE
  To format the guidance from the preceding papers on study design and bias, confounding and meta-analysis, selective reporting, and applicability/directness into checklists of issues for review authors to consider when including NRS in a systematic review.
  Checklists were devised providing frameworks to describe/assess: (1) study designs based on study design features; (2) risk of residual confounding and when to consider meta-analysing data from NRS; (3) risk of selective reporting based on the Cochrane framework for detecting selective outcome reporting in trials but extended to selective reporting of analyses; and (4) directness of evidence contributed by a study to aid integration of NRS findings into summary of findings tables.
  
  
  CONCLUSIONS
  The checklists described will allow review groups to operationalize the inclusion of NRS in systematic reviews in a more consistent way. The next major step is extending the existing Cochrane Risk of Bias tool so that it can assess the risk of bias to NRS included in a review. Copyright © 2013 John Wiley & Sons, Ltd.
authors.affiliation: Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Canada.|Department of Medicine, University of Ottawa, Ottawa, Canada.
authors.forename: George A
authors.initials: GA
authors.lastname: Wells
authors.affiliation: Community Information and Epidemiological Technologies, Institute of Population Health, Ottawa, Canada.
authors.forename: Beverley
authors.initials: B
authors.lastname: Shea
authors.affiliation: MRC Biostatistics Unit, Cambridge, UK.|Centre for Reviews and Dissemination, University of York, York, UK.
authors.forename: Julian Pt
authors.initials: JP
authors.lastname: Higgins
authors.affiliation: School of Social and Community Medicine, University of Bristol, UK.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Sterne
authors.affiliation: Department of Medicine, University of Ottawa, Ottawa, Canada.|Centre for Global Health, Institute of Population Health, Ottawa, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Tugwell
authors.affiliation: Clinical Trials and Evaluation Unit, School of Clinical Sciences, University of Bristol, UK.
authors.forename: Barnaby C
authors.initials: BC
authors.lastname: Reeves
keywords: checklists; methodological issues; non-randomized studies; systematic review