Appraising the evidence
Almost all scientific studies are flawed and it would come as a surprise to some clinicians that some (perhaps most) published papers (ref 1) should be thrown in the bin rather than used to inform clinical practice.
The important thing is not to stop questioning. Curiosity has its own reason for existing.
Albert Einstein 1879-1955
Critical appraisal is a way of rapidly assessing published papers in order to sort out the relevant or valid papers from the poor quality or irrelevent ones.
Validity – is the degree to which the results of the study are likely to be true, believable and free from bias.
Bias – is any factor (other than the experimental factor) that could change the study results in a non-random way.
Critical appraisal is best carried out in a structured/standardised way using explicit criteria. Appraisal can help the clinician to assess:
- Clinical importance
- Clinical relevance
- Appraisal of Guidelines Research and Evaluation AGREE
- CASP (Critical Appraisal Skills Programme) and Appraisal tools
- CASP International e-Learning Module
- Critical Appraisal Skills Programme Español
- Critical Appraisal tools list - from iCAHE – Australia
- CAT Maker software toolt for Critically Apraised Topics – UK Centre for Evidence-based Medicine
- CEBM Oxford- Critical Appraisal tools page – appraisal sheets and calculators
- Dental CATs (Critically Appraised Topics) from University of Texas Health Science Center
- DISCERN. – Instrument for assessing a consumer health information
- EQUATOR Network – resource centre for good reporting of Health research studies
- GATE Appraisal tool – University of Auckland
- SIGN Critical Appraisal checklists
How to Read a Paper series (1997) by Trish Greenhalgh from The British Medical Journal
( In order to access these BMJ articles you will need to register with the BMJ as a free services user)
- The Medline database
- Getting your bearings (deciding what the paper is about)
- Papers that report drug trials
- Papers that report on diagnostic or screening tests
- Papers that summarize other papers (systematic overviews and meta-analyses)
Papers on appraisal from the Canadian Dental Journal series 2001
- Evidence-based Dentistry: Part V. Critical Appraisal of the Dental Literature: Papers about Therapy – Susan E.Sutherland
- Evidence-based Dentistry: Part VI. Critical Appraisal of the Dental Literature: Papers about Diagnosis, Etiology and Prognosis – Susan E.Sutherland
Study Design Series by Kate Ann Levin in the Evidence Based Dentistry Journal
- Study design I. Evid Based Dent. 2005;6(3):78-9.
- Study design II. Issues of chance, bias, confounding and contamination. Evid Based Dent. 2005;6(4):102-3.
- Study design III: Cross-sectional studies. Evid Based Dent. 2006;7(1):24-5
- Study design IV. Cohort studies. Evid Based Dent. 2006;7(2):51-2.
- Study design V. Case-control studies. Evid Based Dent.2006;7(3):83-4.
- Study design VI – Ecological studies. Evid Based Dent.2006;7(4):108.
- Study design VII. Randomised controlled trials. Evid Based Dent.2007;8(1):22-3.