Critical Appraisal

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Critical Appraisal

• Library and Information Service
• Southmead Ext 5333
• Frenchay Ext 6570

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What is critical appraisal?

• . process of weighing up evidence to see how
  useful it is in decision making

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Why critically appraise?

• Supports sound decision making based on best
  available evidence
• Helps us determine
• How rigorous a piece of research is
• What the results are telling us
• How relevant it is to our patient

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How to critically appraise?

• Many different tools
• http//www.cebm.net
• http//www.phru.nhs.uk/casp/apprais.htm
• http//www.shef.ac.uk/scharr/ir/netting
• But what are the three main things we are looking
  for?

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Three Rs

• Rigour - how good is the study
• Results - what is it actually telling us
• Relevance is it relevant to our patient

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Levels of Evidence

• 1a A systematic review of 2 or more randomised
  control trials (RCTs)
• 1b an RCT
• 2a a cohort study
• 2b a case control study
• 2c a dramatic uncontrolled experiment
• 3 Respected authorities, opinions etc
• 4 someone once told me

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Sources of Evidence

• Primary sources
• Based on experiments and published research
• Secondary sources
• Systematic reviews
• Clinical guidelines
• Journals of secondary publication e.g. Evidence
  Based Medicine

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Getting Started

• Formulate PICO question
• Search appropriate sources
• Obtain article (s)
• Read to suit you!

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Statistics

• If in doubt ask a statistician
• Key points to look for
• 95 confidence limits used
• If p lt0.05 then result is statistically
  significant
• Any anomalies discussed
• All subjects accounted for even if dropped out

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Reading for Critical Appraisal

• Introduction
• Logical and knowledgeable
• Aim/research question
• Clearly stated
• Methods
• Fully described
• Analysis
• Appropriate statistics used, all subjects
  accounted for

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• Conclusions
• Justified and valid
• Cost/benefits discussed
• Can I make a clinical decision based on what I
  have just read?

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Practical Exercise

• Appraise the paper given to you and be prepared
  to share your comments with the group

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Appraising Web Sites

• Authority
• Currency
• No advertisement/sponsorship
• .org, .ac, .gov better than .co.uk/.com

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Practical Exercise

• In groups comment on the webpages given and be
  ready to feedback