Evaluation of the Cochrane Collaboration’s tool for assessing the risk of bias in randomized trials: focus groups, online survey, proposed recommendations and their implementation

BackgroundIn 2008, the Cochrane Collaboration introduced a tool for assessing the risk of bias in clinical trials included in Cochrane reviews. The risk of bias (RoB) tool is based on narrative descriptions of evidence-based methodological features known to increase the risk of bias in trials.MethodsTo assess the usability of this tool, we conducted an evaluation by means of focus groups, online surveys and a face-to-face meeting. We obtained feedback from a range of stakeholders within The Cochrane Collaboration regarding their experiences with, and perceptions of, the RoB tool and associated guidance materials. We then assessed this feedback in a face-to-face meeting of experts and stakeholders and made recommendations for improvements and further developments of the RoB tool.ResultsThe survey attracted 380 responses. Respondents reported taking an average of between 10 and 60 minutes per study to complete their RoB assessments, which 83% deemed acceptable. Most respondents (87% of authors and 95% of editorial staff) thought RoB assessments were an improvement over past approaches to trial quality assessment. Most authors liked the standardized approach (81%) and the ability to provide quotes to support judgements (74%). A third of participants disliked the increased workload and found the wording describing RoB judgements confusing. The RoB domains reported to be the most difficult to assess were incomplete outcome data and selective reporting of outcomes. Authors expressed the need for more guidance on how to incorporate RoB assessments into meta-analyses and review conclusions. Based on this evaluation, recommendations were made for improvements to the RoB tool and the associated guidance. The implementation of these recommendations is currently underway.ConclusionsOverall, respondents identified positive experiences and perceptions of the RoB tool. Revisions of the tool and associated guidance made in response to this evaluation, and improved provision of training, may improve implementation.

[1]  G. Guyatt,et al.  Stopping randomized trials early for benefit and estimation of treatment effects: systematic review and meta-regression analysis. , 2010, JAMA.

[2]  J. Higgins,et al.  Cochrane Handbook for Systematic Reviews of Interventions, Version 5.1.0. The Cochrane Collaboration , 2013 .

[3]  Douglas G Altman,et al.  Systematic reviews in health care: Assessing the quality of controlled clinical trials. , 2001, BMJ.

[4]  Isabelle Boutron,et al.  Impact of single centre status on estimates of intervention effects in trials with continuous outcomes: meta-epidemiological study , 2012, BMJ : British Medical Journal.

[5]  R. J. Hayes,et al.  Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. , 1995, JAMA.

[6]  Ya-li Liu,et al.  Risk of Bias Tool in Systematic Reviews/Meta-Analyses of Acupuncture in Chinese Journals , 2011, PloS one.

[7]  Sergio Sismondo,et al.  Industry sponsorship and research outcome. , 2012, The Cochrane database of systematic reviews.

[8]  Ethan M Balk,et al.  Influence of Reported Study Design Characteristics on Intervention Effect Estimates From Randomized, Controlled Trials , 2012, Annals of Internal Medicine.

[9]  A. Stang Critical evaluation of the Newcastle-Ottawa scale for the assessment of the quality of nonrandomized studies in meta-analyses , 2010, European Journal of Epidemiology.

[10]  C. Bias The Cochrane Collaboration's tool for assessing risk of bias in randomised trials , 2011 .

[11]  D. Altman,et al.  Chapter 8: Assessing risk of bias in included studies , 2008 .

[12]  Peter C Gøtzsche,et al.  Bmc Medical Research Methodology Open Access Recommendations by Cochrane Review Groups for Assessment of the Risk of Bias in Studies , 2022 .

[13]  Douglas G Altman,et al.  Empirical evidence of bias in treatment effect estimates in controlled trials with different interventions and outcomes: meta-epidemiological study , 2008, BMJ : British Medical Journal.

[14]  Lisa Hartling,et al.  Risk of bias versus quality assessment of randomised controlled trials: cross sectional study , 2009, BMJ : British Medical Journal.

[15]  P. Tugwell,et al.  The Newcastle-Ottawa Scale (NOS) for Assessing the Quality of Nonrandomised Studies in Meta-Analyses , 2014 .

[16]  Susan Mallett,et al.  QUADAS-2: A Revised Tool for the Quality Assessment of Diagnostic Accuracy Studies , 2011, Annals of Internal Medicine.

[17]  J. Hilden,et al.  Impact of allocation concealment on conclusions drawn from meta-analyses of randomized trials. , 2007, International journal of epidemiology.

[18]  cgohlke,et al.  version 5.0 , 2014 .

[19]  J. Sterne,et al.  The Cochrane Collaboration’s tool for assessing risk of bias in randomised trials , 2011, BMJ : British Medical Journal.

[20]  J. Higgins Cochrane handbook for systematic reviews of interventions. Version 5.1.0 [updated March 2011]. The Cochrane Collaboration , 2011 .

[21]  Lisa Hartling,et al.  Applying the Risk of Bias Tool in a Systematic Review of Combination Long-Acting Beta-Agonists and Inhaled Corticosteroids for Persistent Asthma , 2011, PloS one.

[22]  D. Altman,et al.  Assessing Risk of Bias in Included Studies , 2008 .