Critical Appraisal



Critical appraisal refers to a set of skills for assessing the validity of sources of information, and especially of research reports measuring benefits and harms of health interventions. This assessment involves judgment about both the quality of the work that was done and its application to specific circumstances. Critical appraisal skills are important for all clinicians, policy makers, administrators, researchers, educators and consumers.

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Tutorials, tools, and checklists
About critical appraisal
Toward better understanding of harms of interventions
Systematic reviews on critical appraisal




Tutorials, tools, and checklists

Core topics in evidence-based medicine, JAMAevidence, Journal of the American Medical Association.

Critical appraisal, Centre for Evidence Based Medicine.

Critical appraisal of intervention studies, National Collaborating Centre for Methods and Tools.

Critical Appraisal Skills Programme (CASP), Solutions for Public Health, UK National Health Service.
(handouts for developing and applying critical appraisal skills)

Critical appraisal tools, International Centre for Allied Health Evidence, Division of Health Sciences, University of Southern Australia.

Critically appraised topics tool (CATmaker), Centre for Evidenced Based Medicine, University of Oxford.

Discern online: quality criteria for consumer health information, Institute of Health Sciences, University of Oxford.
(tool and other resources for assessing consumer health information)

Greenhalgh T. How to read a paper: the basics of evidence based medicine, 4th ed. London: BMJ Books, 2010.

Guyatt G, Rennie D, Meade M, Cook D. Users’ guides to the medical literature: a manual for evidence-based clinical practice, 2nd ed. New York: McGraw-Hill, 2008.

Guyatt G, Rennie D, Meade M, Cook D. Users’ guides to the medical literature: essentials of evidence-based clinical practice, 2nd ed. New York: McGraw-Hill, 2008.

Tips and tricks for understanding and using systematic reviews. Regular column in: Evidence-Based Child Health: A Cochrane Review Journal.


About critical appraisal

Alderson P. Absence of evidence is not evidence of absence. BMJ 2004;328(7438):476-7.
(Online Source)

Altman DG, Bland JM. Statistical notes: absence of evidence is not evidence of absence. BMJ. 1995;311(7003):485.

Barratt A, Wyer PC, Hatala R, McGinn T, Dans AL, Keitz S, Moyer V, Guyatt G, for the Evidence-Based Medicine Teaching Tips Working Group. Tips for learners of evidence-based medicine: 1. relative risk reduction, absolute risk reduction and number needed to treat. CMAJ. 2004;171(4):353-8.
(Online Source)

Chalmers I, Matthews R. What are the implications of optimism bias in clinical research? Lancet. 2006;367(9509):449-50.

Glasziou P, Vandenbroucke J, Chalmers I. Assessing the quality of research. BMJ. 2004;328(7430):39-41.
(Online Source)

Hatala R, Keitz S, Wyer P, Gordon Guyatt, for the Evidence-Based Medicine Teaching Tips Working Group. Tips for learners of evidence-based medicine: 4. assessing heterogeneity of primary studies in systematic reviews and whether to combine their results. CMAJ. 2005;172(5):661-5.
(Online Source)

Lewis SC, Warlow CP. How to spot bias and other potential problems in randomised controlled trials. J Neurol Neurosurg Psychiatry. 2004;75(2):181-7.
(Online Source)

McGinn T, Wyer PC, Newman TB, Keitz S, Leipzip R, Guyatt G, for the Evidence-Based Medicine Teaching Tips Working Group. Tips for learners of evidence-based medicine: 3. measures of observer variability (kappa statistic). CMAJ. 2004;171(11):1369-73.
(Online Source)

Montori VM, Kleinbart J, Newman TB, Keitz S, Wyer PC, Moyer V, Guyatt G, for the Evidence-Based Medicine Teaching Tips Working Group. Tips for learners of evidence-based medicine: 2. measures of precision (confidence intervals). CMAJ. 2004:171(6):611-5.
(Online Source)

Thacker SB, Stroup DF, Peterson HB. Meta-analysis for the practicing obstetrician-gynecologist. Clin Obstet Gynecol. 41(2):275-81.

Williams JK. Understanding evidence-based medicine: a primer. Am J Obstet Gynecol. 2001;185(2):275-8.


Toward better understanding of harms of interventions

Chan A-W, Hróbjartsson A, Haahr MT, Gøtzsche PC, Altman DG. Empirical evidence for selective reporting of outcomes in randomized trials: comparison of protocols to published articles. JAMA. 2004;291(20):2457-65.
(Online Source)

Chou R, Helfand M. Challenges in systematic reviews that assess treatment harms. Ann Int Med. 2005;142(12 part 2):1090-9.
(Online Source)

Chou R, Aronson N, Atkins D, Ismaila AS, Santaguida P, Smith DH, Whitlock E, Wilt T, Moher D. AHRQ Series Paper 4: Assessing harms when comparing medical interventions: AHRQ and the Effective Health Care Program (EHCP). Journal Clin Epidemiol. 2010; 63(5):502-512.

Cochrane Adverse Effects Methods Group.

Cuervo LG, Clarke M. Balancing benefits and harms in health care. BMJ. 2003;327(7406):65-66.
(Online Source)

Golder SP, Loke YK, McIntosh HM. Room for Improvement? A survey of the methods used in systematic reviews of adverse effects. BMC Med Res Methodol. 2006;6:3.
(Online Source)

Herxheimer A.  Communicating with patients about risks and harms. PLoS Med. 2005; 2(2):e42.
(Online Source)

Higgins JPT, Green S, editors. Cochrane handbook for systematic reviews of interventions 5.0.2 [updated September 2009];  Chapter 14: Adverse effects. 
(Online Source)

Ioannidis JPA, Evans SJW, Gøtzsche PC, O'Neill RT, Altman DG, Schulz K, Moher D, for the CONSORT Group. Better reporting of harms in randomized trials: an extension of the CONSORT Statement. Ann Int Med. 2004;141(10):781-8.
(Online Source, with appendices)

Ioannidis JPA, Lau J. Completeness of safety reporting in randomized trials: an evaluation of 7 medical areas. JAMA. 2001;285(4):437-43.
(Online Source)

McIntosh HM, Woolacott NF, Bagnall A-M. Assessing harmful effects in systematic reviews. BMC Medical Res Methodol. 2004;4:19.
(Online Source)

Papanikolaou PN, Ioannidis JPA. Availability of large-scale evidence on specific harms from systematic review of randomized trials. Am J Med. 2004;117(8):582-9.


Systematic reviews on critical appraisal

Coomarasamy A, Taylor R, Khan KS. A systematic review of postgraduate teaching in evidence-based medicine and critical appraisal. Med Teach. 2003;25(1):77-81.

Hyde C, Parkes J, Deeks J, Milne R. Systematic review of effectiveness of teaching critical appraisal. Oxford: ICRF/NHS Centre for Statistics in Medicine, Institute of Health Sciences, August 2000.

Katrak P, Bialocerkowski AE, Massy-Westropp N, Saravana Kumar VS, Grimmer KA. A systematic review of the content of critical appraisal tools. BMC Med Res Methodol. 2004;4:22.
(Online Source)

Norman GR, Shannon SI. Effectiveness of instruction in critical appraisal (evidence-based medicine): a critical appraisal. CMAJ. 1998;1582177-81.
(Online Source)

Parkes J, Hyde C, Deeks J, Milne R. Teaching critical appraisal skills in health care settings. Cochrane Database of Syst Rev. 2010, Issue 1.
(Online Source)

Taylor R, Reeves B, Ewings P, Binns S, Keast J, Mears R. A systematic review of the effectiveness of critical appraisal skills training for clinicians. Med Educ. 2000;34(2):120-5.

West S, King V, Carey TS, Lohr KN, McKoy N, Sutton SF, Lux L. Systems to rate the strength of scientific evidence. Rockville, MD: Agency for Healthcare Research and Quality, April 2002. (Evidence Report/Technology Assessment 47.)
(Online Source, PDF)




Most recent page update: 2/4/2011


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