Critical appraisal
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Critical appraisal



Critical appraisal workshop delivered to East of England Health Libraries Network, 1st April 2014

Critical appraisal workshop delivered to East of England Health Libraries Network, 1st April 2014



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Critical appraisal Critical appraisal Presentation Transcript

  • Critical appraisal Paula Funnell Faculty Liaison Librarian (Medicine and Dentistry) Introduction to
  • Outline Introduction to critical appraisal Appraising quantitative research Levels of evidence Statistics Group appraisal Appraising qualitative research Qualitative methodologies Group appraisal Running a critical appraisal workshop
  • Introduction
  • Evidence based healthcare “When we intervene in the lives of others we should do so on the basis of the best evidence available regarding the likely consequences of that intervention” G Macdonald, 1998 Macdonald, G. (1998). Promoting Evidence-Based Practice in Child Protection. Clinical Child Psychology and Psychiatry, 3 (1), 71–85.
  • Steps of evidence based healthcare 1. The patient presents with a clinical problem 2. Formulate a focused research question 3. Search for the best evidence 4. Critically appraise the evidence you find 5. Consider the evidence in the light of your expertise and decide whether to apply it or not
  • Why critically appraise? To weigh up how valid and useful the research will be
  • Why critically appraise? • In order to keep up to date, clinicians would have to read 17 articles a day, 365 days a year • Research is of variable quality • Only an estimated 1% is judged clinically relevant • Need to find the 1%
  • How it works • Involves answering a short questionnaire • We use the CASP questionnaires at • The questionnaires were devised by clinicians for clinicians • Remember to focus on appraisal not criticism
  • Quantitative research
  • What is quantitative research? • Research on something that can be accurately measured • Tends to use large, statistically representative samples • Uses statistical methods to analyse data • Represents findings with numbers • Attempts to eliminate bias
  • Systematic reviews • A review of all the literature on a topic • Systematically identified • Appraised • Summarised
  • Question 1 Did the review ask a clearly focused question?
  • PICO A focused clinical question: P I C O Population / patient / problem Intervention Comparison Outcome
  • Question 2 Did the authors look for the right type of papers?
  • Levels of evidence (therapy)
  • Systematic reviews RCTs Cohort studies Case control studies Expert opinion 1a 1b 2 3 4 5 Case series Levels of evidence (therapy)
  • Randomised controlled trials Outcome Outcome new treatment control treatment
  • Question 3 Do you think the important relevant studies were included?
  • Publication bias Papers with “interesting” results are more likely to be: • Submitted and accepted for publication • Published in a major journal • Published in English • Quoted by authors • Quoted in newspapers
  • Question 4 Did the review’s authors do enough to assess the quality of the included studies?
  • RCT checklist
  • Quality assessment • Were the inclusion/exclusion criteria clear? • Did they use any sort of scoring system? • Were the studies for inclusion assessed by more than one reviewer?
  • Question 5 If the results of the review have been combined, was it reasonable to do so?
  • Heterogeneity • Are the studies similar in terms of: – Population – Intervention – Outcome – Methodology • Are the results similar from study to study? • Were any tests for heterogeneity carried out? • Are there any discussions around heterogeneity?
  • Question 6 What are the overall results of the review?
  • How are the results presented? • Number needed to treat (NNT) • Odds Ratio • Relative risk • Mean difference
  • Odds and risk Odds of winning You versus the rest Risk of winning You versus all the runners 10 horses running, you bet on 1 horse 1:9 1:10
  • Odds and risk Odds of winning You versus the rest Risk of winning You versus all the runners 10 horses running, you bet on 4 horses 4:6 4:10
  • Forest plots more than 1less than 1 1
  • Forest plots more than 1less than 1 1 Line of no effect
  • Forest plots more than 1less than 1 1 Line of no effect
  • Forest plots more than 1less than 1 1 Line of no effect Best estimate
  • Forest plots more than 1less than 1 1 Line of no effect Best estimate Confidence interval
  • Forest plots more than 1less than 1 1 Line of no effect Best estimate Confidence interval
  • Forest plots more than 1less than 1 1 Line of no effect Best estimate Pooled result Confidence interval
  • Question 7 How precise are the results?
  • Confidence intervals Practical exercise
  • P-value Could the result have occurred by chance? p = 0.001 (1 in 1000) p = 0.2 (1 in 5) A p-value of less than 0.05 (1 in 20) is considered to be statistically significant
  • Question 8 Can the results be applied to the local population?
  • Application • Difficult to answer if you don‟t have your own population • Need to rely on experts • Think about whether the study could be easy replicated with another population
  • Question 9 Were all the important outcomes considered?
  • Outcomes • Do the authors address all the outcomes they set out to study? • Are the outcomes considered from different viewpoints e.g. patient, practitioners, policy makers?
  • Question 10 Are the benefits worth the harms and the costs?
  • Benefit v harms and costs • How significant are the benefits? • Is there any discussion of possible side effects etc.? • Are financial costs mentioned?
  • Summary Validity Is it trustworthy? Results What does it say? Relevance Will it help?
  • Qualitative research
  • What is qualitative research? • Concerned with the world of human experience from the view of the participants • Natural settings are used • A study is „led‟ by the subjects‟ experiences • Qualitative research is rigorous and systematic • Results are not usually generalisable or totally replicable
  • Components of qualitative research Research question Sampling process Data collection Data analysis
  • Question 1 Was there a clear statement of the aims of the research?
  • The research question • Describes why the research is being carried out • Qualitative research addresses the questions • Are the aims of the research clear?
  • Question 2 Is a qualitative methodology appropriate?
  • Why qualitative research? • Increases knowledge in an area that is poorly understood • Challenges assumptions and practices • Acts as a precursor to quantitative research • Generates new ideas
  • Question 3 Was the research design appropriate to address the aims of the research?
  • Research methodologies phenomenology field research grounded theory action research ethnography
  • Question 4 Was the recruitment strategy appropriate to the aims of the research?
  • Sampling • Sample size can be determined by – Data analysis – Time constraints • What population does the sample refer to? • How was the sample selected?
  • Sampling Methods of sampling: • Convenience • Purposive • Quota • Snowballing
  • Question 5 Was the data collected in a way that addressed the research issue?
  • Data collection • Are the methods the most suitable for the research question? • Are the methods explicit? • Is the venue clearly described?
  • Question 6 Has the relationship between researcher and participants been adequately considered?
  • Reflexivity and researcher bias VenueArea being studied Types of interview questions asked Meaning given to data
  • Question 7 Have ethical issues been taken into consideration?
  • Ethics Need to consider: • Consent • Confidentiality • Professional responsibility • Reporting • Ethics committee approval
  • Question 8 Was the data analysis sufficiently rigorous?
  • Data analysis • Description of analysis • Clarity of approach • Use of all the data • Potential for bias
  • Question 9 Is there a clear statement of findings?
  • The findings • Are the findings explicit? • Are they credible? – respondent validation – quality of argument – would another researcher make a similar interpretation? – are alternative interpretations explored?
  • Triangulation questionnaire professionals
  • Question 10 How valuable is the research?
  • Value of the research Consider your appraisal of the paper in terms of: • Credibility • Dependability • Transferability • Confirmability How useful is the paper to you?
  • Questions to ask
  • Running a critical appraisal workshop
  • Before the session • Who is the group? • Is it qualitative, quantitative, or both? • Know what equipment and facilities are available • Ask participants to read the article in advance
  • Structuring the session • Dependent on the group and time frame • Presentation • Encourage audience participation • Use interactive activities • Practical critical appraisal in groups • Feedback
  • Choosing an article • For a mixed group choose a fairly generic article • For a discipline specific group: – Do you want to use a discipline specific article? – Ask for topic ideas – Not a good idea to let them choose the articles • Choose studies with both strengths and weaknesses • Make sure it‟s easily available to all the participants
  • Any Questions? The end! Paula Funnell Faculty Liaison Librarian (Medicine & Dentistry) Queen Mary University of London