Critical Appraisal: Assessing the Quality of Studies

There is great variation in the type and quality of research evidence. Having completed your search and assembled your studies, the next step is to critically appraise the studies to ascertain their quality. Ultimately you will be making a judgement about the overall evidence, but that comes later. You will see throughout this chapter that we make a clear differentiation between the individual studies and what we call the body of evidence, which is all of the studies and anything else that we use to answer the question or to make a recommendation. This chapter deals with only the first of these—the individual studies. Critical appraisal, like everything else in systematic literature reviewing, is a scientific exercise that requires individual judgement, and we describe some tools to help you.

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References

  1. Oxford Centre for Evidence-Based Medicine (OCEBM) (2016) OCEBM levels of evidence. In: CEBM. https://www.cebm.net/2016/05/ocebm-levels-of-evidence/. Accessed 17 Apr 2020
  2. Aromataris E, Munn Z (eds) (2017) Joanna Briggs Institute reviewer’s manual. The Joanna Briggs Institute, Adelaide Google Scholar
  3. Daly J, Willis K, Small R et al (2007) A hierarchy of evidence for assessing qualitative health research. J Clin Epidemiol 60:43–49. https://doi.org/10.1016/j.jclinepi.2006.03.014ArticlePubMedGoogle Scholar
  4. EQUATOR Network (2020) What is a reporting guideline?—The EQUATOR Network. https://www.equator-network.org/about-us/what-is-a-reporting-guideline/. Accessed 7 Mar 2020
  5. Tong A, Sainsbury P, Craig J (2007) Consolidated criteria for reporting qualitative research (COREQ): a 32-item checklist for interviews and focus groups. Int J Qual Health Care 19:349–357. https://doi.org/10.1093/intqhc/mzm042ArticlePubMedGoogle Scholar
  6. von Elm E, Altman DG, Egger M et al (2007) The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. PLoS Med 4:e296. https://doi.org/10.1371/journal.pmed.0040296ArticleGoogle Scholar
  7. Brouwers MC, Kerkvliet K, Spithoff K, AGREE Next Steps Consortium (2016) The AGREE reporting checklist: a tool to improve reporting of clinical practice guidelines. BMJ 352:i1152. https://doi.org/10.1136/bmj.i1152ArticlePubMedPubMed CentralGoogle Scholar
  8. Moher D, Liberati A, Tetzlaff J et al (2009) Preferred reporting items for systematic reviews and meta-analyses: the PRISMA statement. PLoS Med 6:e1000097. https://doi.org/10.1371/journal.pmed.1000097ArticlePubMedPubMed CentralGoogle Scholar
  9. Boutron I, Page MJ, Higgins JPT, Altman DG, Lundh A, Hróbjartsson A (2019) Chapter 7: Considering bias and conflicts of interest among the included studies. In: Higgins JPT, Thomas J, Chandler J, Cumpston M, Li T, Page MJ, Welch VA (eds). Cochrane Handbook for Systematic Reviews of Interventions version 6.0 (updated July 2019), Cochrane. https://www.training.cochrane.org/handbook
  10. Critical Appraisal Skills Programme (2018) CASP checklists. In: CASP—critical appraisal skills programme. https://casp-uk.net/casp-tools-checklists/. Accessed 7 Mar 2020
  11. Higgins JPT, Savović J, Page MJ et al (2019) Chapter 8: Assessing risk of bias in a randomized trial. In: Higgins JPT, Thomas J, Chandler J et al (eds) Cochrane handbook for systematic reviews of interventions version 6.0 (updated July 2019). Cochrane, London ChapterGoogle Scholar
  12. Guyatt GH, Oxman AD, Kunz R et al (2011) GRADE guidelines 6. Rating the quality of evidence—imprecision. J Clin Epidemiol 64:1283–1293. https://doi.org/10.1016/j.jclinepi.2011.01.012ArticlePubMedGoogle Scholar
  13. Sterne JAC, Savović J, Page MJ et al (2019) RoB 2: a revised tool for assessing risk of bias in randomised trials. BMJ 366:l4898. https://doi.org/10.1136/bmj.l4898ArticlePubMedGoogle Scholar
  14. Sterne JA, Hernán MA, Reeves BC et al (2016) ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. BMJ 355:i4919. https://doi.org/10.1136/bmj.i4919ArticlePubMedPubMed CentralGoogle Scholar
  15. Wells GA, Shea B, O’Connell D et al (2019) The Newcastle-Ottawa Scale (NOS) for assessing the quality of nonrandomised studies in meta-analyses. Ottawa Hospital Research Institute, Ottawa. http://www.ohri.ca/programs/clinical_epidemiology/oxford.asp. Accessed 7 Mar 2020 Google Scholar
  16. Cochrane Community (2020) Glossary—Cochrane community. https://community.cochrane.org/glossary#letter-R. Accessed 8 Mar 2020
  17. Messick S (1989) Meaning and values in test validation: the science and ethics of assessment. Educ Res 18:5–11. https://doi.org/10.3102/0013189X018002005ArticleGoogle Scholar
  18. Sparkes AC (2001) Myth 94: qualitative health researchers will agree about validity. Qual Health Res 11:538–552. https://doi.org/10.1177/104973230101100409ArticleCASPubMedGoogle Scholar
  19. Aguinis H, Solarino AM (2019) Transparency and replicability in qualitative research: the case of interviews with elite informants. Strat Manag J 40:1291–1315. https://doi.org/10.1002/smj.3015ArticleGoogle Scholar
  20. Lincoln YS, Guba EG (1985) Naturalistic inquiry. Sage Publications, Beverly Hills, CA BookGoogle Scholar
  21. Hannes K (2011) Chapter 4: Critical appraisal of qualitative research. In: Noyes J, Booth A, Hannes K et al (eds) Supplementary guidance for inclusion of qualitative research in Cochrane systematic reviews of interventions. Cochrane Collaboration Qualitative Methods Group, London Google Scholar
  22. Munn Z, Porritt K, Lockwood C et al (2014) Establishing confidence in the output of qualitative research synthesis: the ConQual approach. BMC Med Res Methodol 14:108. https://doi.org/10.1186/1471-2288-14-108ArticlePubMedPubMed CentralGoogle Scholar
  23. Toye F, Seers K, Allcock N et al (2013) ‘Trying to pin down jelly’—exploring intuitive processes in quality assessment for meta-ethnography. BMC Med Res Methodol 13:46. https://doi.org/10.1186/1471-2288-13-46ArticlePubMedPubMed CentralGoogle Scholar
  24. Katikireddi SV, Egan M, Petticrew M (2015) How do systematic reviews incorporate risk of bias assessments into the synthesis of evidence? A methodological study. J Epidemiol Community Health 69:189–195. https://doi.org/10.1136/jech-2014-204711ArticlePubMedGoogle Scholar
  25. McKenzie JE, Brennan SE, Ryan RE et al (2019) Chapter 9: Summarizing study characteristics and preparing for synthesis. In: Higgins JPT, Thomas J, Chandler J et al (eds) Cochrane handbook for systematic reviews of interventions version 6.0 (updated July 2019). Cochrane, London Google Scholar
  26. Deeks JJ, Higgins JPT, Altman DG (2019) Chapter 10: Analysing data and undertaking meta-analyses. In: Higgins JPT, Thomas J, Chandler J et al (eds) Cochrane handbook for systematic reviews of interventions version 6.0 (updated July 2019). Cochrane, London Google Scholar

Author information

Authors and Affiliations

  1. School of Health Sciences, City, University of London, London, UK Edward Purssell
  2. Florence Nightingale Faculty of Nursing, Midwifery & Palliative Care, King’s College London, London, UK Niall McCrae
  1. Edward Purssell