How to critically appraise an article


Critical appraisal is a systematic process used to identify the strengths and weaknesses of a research article in order to assess the usefulness and validity of research findings. The most important components of a critical appraisal are an evaluation of the appropriateness of the study design for the research question and a careful assessment of the key methodological features of this design. Other factors that also should be considered include the suitability of the statistical methods used and their subsequent interpretation, potential conflicts of interest and the relevance of the research to one's own practice. This Review presents a 10-step guide to critical appraisal that aims to assist clinicians to identify the most relevant high-quality studies available to guide their clinical practice.

Key Points

  • Critical appraisal is a systematic process used to identify the strengths and weaknesses of a research article

  • Critical appraisal provides a basis for decisions on whether to use the results of a study in clinical practice

  • Different study designs are prone to various sources of systematic bias

  • Design-specific, critical-appraisal checklists are useful tools to help assess study quality

  • Assessments of other factors, including the importance of the research question, the appropriateness of statistical analysis, the legitimacy of conclusions and potential conflicts of interest are an important part of the critical appraisal process

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Consolidated standards of reporting trials (CONSORT) statement flowchart for the standard reporting and appraisal of randomized controlled trials.
Figure 2: Standards for the reporting of diagnostic accuracy studies (STARD) statement flowchart for the standard reporting and appraisal of studies examining the accuracy of diagnostic tests.


  1. 1

    Druss BG and Marcus SC (2005) Growth and decentralisation of the medical literature: implications for evidence-based medicine. J Med Libr Assoc 93: 499–501

    PubMed  PubMed Central  Google Scholar 

  2. 2

    Glasziou PP (2008) Information overload: what's behind it, what's beyond it? Med J Aust 189: 84–85

    PubMed  Google Scholar 

  3. 3

    Last JE (Ed.; 2001) A Dictionary of Epidemiology (4th Edn). New York: Oxford University Press

    Google Scholar 

  4. 4

    Sackett DL et al. (2000). Evidence-based Medicine. How to Practice and Teach EBM. London: Churchill Livingstone

    Google Scholar 

  5. 5

    Guyatt G and Rennie D (Eds; 2002). Users' Guides to the Medical Literature: a Manual for Evidence-based Clinical Practice. Chicago: American Medical Association

    Google Scholar 

  6. 6

    Greenhalgh T (2000) How to Read a Paper: the Basics of Evidence-based Medicine. London: Blackwell Medicine Books

    Google Scholar 

  7. 7

    MacAuley D (1994) READER: an acronym to aid critical reading by general practitioners. Br J Gen Pract 44: 83–85

    CAS  PubMed  PubMed Central  Google Scholar 

  8. 8

    Hill A and Spittlehouse C (2001) What is critical appraisal. Evidence-based Medicine 3: 1–8 [] (accessed 25 November 2008)

    Google Scholar 

  9. 9

    Public Health Resource Unit (2008) Critical Appraisal Skills Programme (CASP). [] (accessed 8 August 2008)

  10. 10

    National Health and Medical Research Council (2000) How to Review the Evidence: Systematic Identification and Review of the Scientific Literature. Canberra: NHMRC

  11. 11

    Elwood JM (1998) Critical Appraisal of Epidemiological Studies and Clinical Trials (2nd Edn). Oxford: Oxford University Press

    Google Scholar 

  12. 12

    Agency for Healthcare Research and Quality (2002) Systems to rate the strength of scientific evidence? Evidence Report/Technology Assessment No 47, Publication No 02-E019 Rockville: Agency for Healthcare Research and Quality

  13. 13

    Crombie IK (1996) The Pocket Guide to Critical Appraisal: a Handbook for Health Care Professionals. London: Blackwell Medicine Publishing Group

    Google Scholar 

  14. 14

    Heller RF et al. (2008) Critical appraisal for public health: a new checklist. Public Health 122: 92–98

    Article  Google Scholar 

  15. 15

    MacAuley D et al. (1998) Randomised controlled trial of the READER method of critical appraisal in general practice. BMJ 316: 1134–37

    CAS  Article  Google Scholar 

  16. 16

    Parkes J et al. Teaching critical appraisal skills in health care settings (Review). Cochrane Database of Systematic Reviews 2005, Issue 3. Art. No.: cd001270. 10.1002/14651858.cd001270

    Google Scholar 

  17. 17

    Mays N and Pope C (2000) Assessing quality in qualitative research. BMJ 320: 50–52

    CAS  Article  Google Scholar 

  18. 18

    Hawking SW (2003) On the Shoulders of Giants: the Great Works of Physics and Astronomy. Philadelphia, PN: Penguin

    Google Scholar 

  19. 19

    National Health and Medical Research Council (1999) A Guide to the Development, Implementation and Evaluation of Clinical Practice Guidelines. Canberra: National Health and Medical Research Council

  20. 20

    US Preventive Services Taskforce (1996) Guide to clinical preventive services (2nd Edn). Baltimore, MD: Williams & Wilkins

  21. 21

    Solomon MJ and McLeod RS (1995) Should we be performing more randomized controlled trials evaluating surgical operations? Surgery 118: 456–467

    Article  Google Scholar 

  22. 22

    Rothman KJ (2002) Epidemiology: an Introduction. Oxford: Oxford University Press

    Google Scholar 

  23. 23

    Young JM and Solomon MJ (2003) Improving the evidence-base in surgery: sources of bias in surgical studies. ANZ J Surg 73: 504–506

    Article  Google Scholar 

  24. 24

    Margitic SE et al. (1995) Lessons learned from a prospective meta-analysis. J Am Geriatr Soc 43: 435–439

    CAS  Article  Google Scholar 

  25. 25

    Shea B et al. (2001) Assessing the quality of reports of systematic reviews: the QUORUM statement compared to other tools. In Systematic Reviews in Health Care: Meta-analysis in Context 2nd Edition, 122–139 (Eds Egger M. et al.) London: BMJ Books

    Google Scholar 

  26. 26

    Easterbrook PH et al. (1991) Publication bias in clinical research. Lancet 337: 867–872

    CAS  Article  Google Scholar 

  27. 27

    Begg CB and Berlin JA (1989) Publication bias and dissemination of clinical research. J Natl Cancer Inst 81: 107–115

    CAS  Article  Google Scholar 

  28. 28

    Moher D et al. (2000) Improving the quality of reports of meta-analyses of randomised controlled trials: the QUORUM statement. Br J Surg 87: 1448–1454

    CAS  Article  Google Scholar 

  29. 29

    Shea BJ et al. (2007) Development of AMSTAR: a measurement tool to assess the methodological quality of systematic reviews. BMC Medical Research Methodology 7: 10 [10.1186/1471-2288-7-10]

    Google Scholar 

  30. 30

    Stroup DF et al. (2000) Meta-analysis of observational studies in epidemiology: a proposal for reporting. Meta-analysis Of Observational Studies in Epidemiology (MOOSE) group. JAMA 283: 2008–2012

    CAS  Article  Google Scholar 

  31. 31

    Young JM and Solomon MJ (2003) Improving the evidence-base in surgery: evaluating surgical effectiveness. ANZ J Surg 73: 507–510

    Article  Google Scholar 

  32. 32

    Schulz KF (1995) Subverting randomization in controlled trials. JAMA 274: 1456–1458

    CAS  Article  Google Scholar 

  33. 33

    Schulz KF et al. (1995) Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials. JAMA 273: 408–412

    CAS  Article  Google Scholar 

  34. 34

    Moher D et al. (2001) The CONSORT statement: revised recommendations for improving the quality of reports of parallel group randomized trials. BMC Medical Research Methodology 1: 2 [ 1471-2288/1/2] (accessed 25 November 2008)

    CAS  Article  Google Scholar 

  35. 35

    Rochon PA et al. (2005) Reader's guide to critical appraisal of cohort studies: 1. Role and design. BMJ 330: 895–897

    Article  Google Scholar 

  36. 36

    Mamdani M et al. (2005) Reader's guide to critical appraisal of cohort studies: 2. Assessing potential for confounding. BMJ 330: 960–962

    Article  Google Scholar 

  37. 37

    Normand S et al. (2005) Reader's guide to critical appraisal of cohort studies: 3. Analytical strategies to reduce confounding. BMJ 330: 1021–1023

    Article  Google Scholar 

  38. 38

    von Elm E et al. (2007) Strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. BMJ 335: 806–808

    Article  Google Scholar 

  39. 39

    Sutton-Tyrrell K (1991) Assessing bias in case-control studies: proper selection of cases and controls. Stroke 22: 938–942

    CAS  Article  Google Scholar 

  40. 40

    Knottnerus J (2003) Assessment of the accuracy of diagnostic tests: the cross-sectional study. J Clin Epidemiol 56: 1118–1128

    CAS  Article  Google Scholar 

  41. 41

    Furukawa TA and Guyatt GH (2006) Sources of bias in diagnostic accuracy studies and the diagnostic process. CMAJ 174: 481–482

    Article  Google Scholar 

  42. 42

    Bossyut PM et al. (2003)The STARD statement for reporting studies of diagnostic accuracy: explanation and elaboration. Ann Intern Med 138: W1–W12

    Article  Google Scholar 

  43. 43

    STARD statement (Standards for the Reporting of Diagnostic Accuracy Studies). [] (accessed 10 September 2008)

  44. 44

    Raftery J (1998) Economic evaluation: an introduction. BMJ 316: 1013–1014

    CAS  Article  Google Scholar 

  45. 45

    Palmer S et al. (1999) Economics notes: types of economic evaluation. BMJ 318: 1349

    CAS  Article  Google Scholar 

  46. 46

    Russ S et al. (1999) Barriers to participation in randomized controlled trials: a systematic review. J Clin Epidemiol 52: 1143–1156

    Article  Google Scholar 

  47. 47

    Tinmouth JM et al. (2004) Are claims of equivalency in digestive diseases trials supported by the evidence? Gastroentrology 126: 1700–1710

    Article  Google Scholar 

  48. 48

    Kaul S and Diamond GA (2006) Good enough: a primer on the analysis and interpretation of noninferiority trials. Ann Intern Med 145: 62–69

    Article  Google Scholar 

  49. 49

    Piaggio G et al. (2006) Reporting of noninferiority and equivalence randomized trials: an extension of the CONSORT statement. JAMA 295: 1152–1160

    CAS  Article  Google Scholar 

  50. 50

    Heritier SR et al. (2007) Inclusion of patients in clinical trial analysis: the intention to treat principle. In Interpreting and Reporting Clinical Trials: a Guide to the CONSORT Statement and the Principles of Randomized Controlled Trials, 92–98 (Eds Keech A. et al.) Strawberry Hills, NSW: Australian Medical Publishing Company

    Google Scholar 

  51. 51

    National Health and Medical Research Council (2007) National Statement on Ethical Conduct in Human Research 89–90 Canberra: NHMRC

  52. 52

    Lo B et al. (2000) Conflict-of-interest policies for investigators in clinical trials. N Engl J Med 343: 1616–1620

    CAS  Article  Google Scholar 

  53. 53

    Kim SYH et al. (2004) Potential research participants' views regarding researcher and institutional financial conflicts of interests. J Med Ethics 30: 73–79

    CAS  Article  Google Scholar 

  54. 54

    Komesaroff PA and Kerridge IH (2002) Ethical issues concerning the relationships between medical practitioners and the pharmaceutical industry. Med J Aust 176: 118–121

    PubMed  Google Scholar 

  55. 55

    Little M (1999) Research, ethics and conflicts of interest. J Med Ethics 25: 259–262

    CAS  Article  Google Scholar 

  56. 56

    Lemmens T and Singer PA (1998) Bioethics for clinicians: 17. Conflict of interest in research, education and patient care. CMAJ 159: 960–965

    CAS  PubMed  PubMed Central  Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Jane M Young.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Young, J., Solomon, M. How to critically appraise an article. Nat Rev Gastroenterol Hepatol 6, 82–91 (2009).

Download citation

Further reading


Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing