What is the Risk of Bias Assessment and Different Tools used to Assess Systematic Review Dr. Nancy Agens, Head, Technical Operations, Pubrica
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In Brief The risk of bias is defined as the risk of systematic error or a deviation from reporting the truth or an appropriate evidence finding. It occurs when there is a systematic flaw or limitations in the study design or the conduct of the study. This article describes different assessment tools and the types of study designs for which the tool is applicable along with the flow of how to avoid the risk of bias. I. INTRODUCTION A systematic review guideline will often determine the study design to answer the formulated question, and it is not enough in trusting the evidence of systematic review over observational studies. There are several terms like quality assessment, critical appraisal, or internal validity, which are used for the evaluation of studies supported by the guideline. Whereas in the risk of bias, the bias determines the factor that can affect the observations and findings of the study systematically and report it to be different from the actual conclusion. In other words, a study affected by bias can be inaccurate and thus leads to an inappropriate guideline recommendation. Therefore, inadequate study design or the conduct of the study will give false findings which result in wasting time and resources, and missing opportunity for effective intervention. Quality assessment or risk of bias assessment helps in regulating and establishing transparency of evidence synthesis (data collection methods, search
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strategies, etc.) and findings and it is often performed for each study in a review; thus the collected evidence eliminate bias in the outcomes. Generally, a quality assessment outside of a systematic review does not require evidence synthesis method; however, it completely depends upon the utilization of evidence synthesis method. The risk of bias assessment can be done by professionals who may be conducted by the guideline development group or requires a methodological expert or by experiences systematic review researchers. Once the evaluation is done, then it can be used for the synthesis of study results and findings and combined into the complete assessment of the evidence. There are certain common factors which can introduce bias in many research areas, that include Selection bias – Participant or Population comparability in a study Performance bias – The influence of estimate effect (aspects other than the intervention or exposure of interest) Reporting bias – Problems with measurements or classification of outcome (missing information) The risk of bias is assessed frequently by evaluating the study design and the conduct of the study because it is impossible to determine a specific study has been affected by bias or not. II. DIFFERENT TOOLS USED TO ASSESS THE RISK OF BIAS IN THE SYSTEMATIC REVIEW AMSTAR 2 - A MeaSurement Tool to Assess systematic Reviews AHRQ RRB - AHRQ tool for evaluating the Risk of Reporting Bias
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AHRQ ORB – AHRQ Outcome and analysis Reporting Bias framework GRADE – Grading of Recommendations Assessment, Development and Evaluation GRADE-CERQual – GRADE Confidence in Evidence from Reviews of Qualitative research SAQAT – Semi-Automated Quality Assessment Tool NMA Quality – Framework for evaluating the quality of evidence from a Network Meta-Analysis NOS - Newcastle-Ottawa Scale AXIS – Appraisal tool for CrossSectional Studies QUIPS - QUality In Prognosis Studies tool RoB 1.0 – Cochrane Risk of Bias tool for randomized trials RoB 2.0 - Revised tool for Assessing Risk of Bias in randomized trials SYRCLE RoB – SYstematic Review Centre for Laboratory animal Experimentation Risk of Bias tool SciRAP - Science in Risk Assessment and Policy SIGN - The Scottish Intercollegiate Guidelines Network ROBIS - Risk Of Bias in Systematic Reviews RoBANS - Risk of Bias Assessment Tool for Nonrandomized Studies RoBINS I - Risk of Bias In Nonrandomized Studies of Interventions tool ORBIT 1 – Outcome Reporting Bias In Trials classification system for benefit outcomes
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QUADAS 2 - Quality Assessment of Diagnostic Accuracy Studies PROBAST - Prediction model Risk Of Bias ASsessment Tool ORBIT 2 - Outcome Reporting Bias In Trials classification system for harm outcomes Reid – Selective reporting bias algorithm RTI 2012 – RTI Item Bank for Assessment of Risk of Bias and Precision for Observational Studies of Interventions or Exposures RTI 2013 – RTI Item Bank for Assessing Risk of Bias and Confounding for Observational Studies of Interventions or Exposures JBI - the Joanna Briggs Institute OHAT - Office of Health Assessment and Translation Downs Black - Downs Black tool III. HOW TO ASSESS THE RISK OF BIAS 1. Plan your approach 2. Identifying an appropriate risk of bias assessment tool 3. Be aware of related issues 4. Appraise each study 5. Report the assessment process 6. Use your appraisals to inform the guideline IV. DETERMINING AN APPROPRIATE RISK OF BIAS ASSESSMENT TOOL
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Study type
Systematic reviews
Assessment tools
Year Source
AMSTAR - 2
2017
ROBIS
2016
SIGN checklist
2014
https://amstar.ca/Amstar-2.php www.bristol.ac.uk/population-healthsciences/projects/robis/ https://www.sign.ac.uk/checklists-andnotes.html
Cochrane RoB 2.0 2016 Tool
www.riskofbias.info
SIGN checklist
2014
https://www.sign.ac.uk/checklists-andnotes.html
Non-randomised studies of ROBINS-I interventions (case-control, cohort, etc.) SIGN checklist
2016
www.riskofbias.info
Randomized trials
Prognostic: Prognostic factors Risk prediction modelling Overall prognosis/baseline risk/prevalence/inciden ce
JBI checklist for 2017 prevalence studies
https://www.sign.ac.uk/checklists-andnotes.html http://joannabriggs.org/research/critica l-appraisal-tools.html
PROBAST
2014
www.systematic-reviews.com/probast
QUIPS
2013
https://methods.cochrane.org/prognosi s/welcome
SIGN checklist
2014
QUADAS-2
2011
2014
Diagnostic
CASP Qualitative 2018 Checklist Qualitative
GRADE-CERQual
2017
JBI Checklist for 2017 Qualitative Research Navigation Guide 2018 Observational studies of risk of bias checklist exposures (human epidemiology, wildlife) OHAT tool 2015
In vivo animal studies
In vitro studies
https://www.sign.ac.uk/checklists-andnotes.html www.bristol.ac.uk/population-healthsciences/projects/quadas/quadas-2 https://casp-uk.net/wpcontent/uploads/2018/01/CASPQualitative-Checklist-2018.pdf https://www.cerqual.org/ http://joannabriggs.org/research/critica l-appraisal-tools.html https://www.cosmin.nl/ https://ntp.niehs.nih.gov/ntp/ohat/pubs /riskofbiastool_508.pdf
Navigation Guide 2018 risk of bias checklist
https://www.cosmin.nl/
SciRAP tool
2018
http://www.scirap.org/
OHAT tool
2015
CRED
2016
SYRCLE tool
2014
OHAT tool
2015
https://ntp.niehs.nih.gov/ntp/ohat/pubs /riskofbiastool_508.pdf www.ecotoxcentre.ch/projects/riskassessment/cred Systematic Review Centre for Laboratory Animal Experimentation https://ntp.niehs.nih.gov/ntp/ohat/pubs /riskofbiastool_508.pdf
Obtained from: https://www.nhmrc.gov.au/guidelinesforguidelines/develop/assessing-risk-bias# Copyright © 2020 pubrica. All rights reserved
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In summary, risk of bias assessment is a tool used to regulate findings which are accurate and appropriate, and it is essential to select the risk of bias tool rightly. There are many researches available to help, and it makes things easier to find appropriate tools for assessing the risk of bias. This article describes different assessment tools for a systematic review and the types of study designs for which the tool is applicable along with the flow of how to avoid the risk of bias. REFERENCE 1.
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Bero, L. A. Why the Cochrane risk of bias tool should include funding source as a standard item. Cochrane Database of Systematic Reviews, 2013. Higgins, J. P., J. Savović, et al., Eds. Revised Cochrane the risk of bias tool for randomized trials, 20 October 2016. Marshall, I. J., A. Noel-Storr, et al. Machine learning for identifying Randomized Controlled Trials: An evaluation and practitioner's guide. Research Synthesis Methods, 2016. Reeves, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomized or non-randomised studies of healthcare interventions, or both. British Medical Journal 358, 2017. Whiting, P., J. Savović, et al. ROBIS: A new tool to assess the risk of bias in systematic reviews was developed. Journal of Clinical Epidemiology 69: 225-234, 2016.
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