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

1. Critical appraisal
Paula Funnell
p.a.funnell@qmul.ac.uk
Faculty Liaison Librarian
(Medicine and Dentistry)
Introduction to

2. 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

3. Introduction

4. 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.

5. 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

6. Why critically appraise?
To weigh up how valid and useful
the research will be

7. 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%

8. How it works
• Involves answering a short
questionnaire
• We use the CASP questionnaires at
http://www.casp-uk.net/
• The questionnaires were devised by
clinicians for clinicians
• Remember to focus on appraisal not
criticism

9. Quantitative research

10. 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

11. Systematic reviews
• A review of all the literature on a topic
• Systematically identified
• Appraised
• Summarised

12. Question 1
Did the review ask a clearly
focused question?

13. PICO
A focused clinical question:
P
I
C
O
Population / patient / problem
Intervention
Comparison
Outcome

14. Question 2
Did the authors look for the right
type of papers?

15. Levels of evidence (therapy)

16. Systematic reviews
RCTs
Cohort studies
Case control studies
Expert opinion
1a
1b
2
3
4
5
Case series
http://www.cebm.net/index.aspx?o=1025
Levels of evidence (therapy)

17. Randomised controlled trials
Outcome
Outcome
new treatment
control treatment

18. Question 3
Do you think the important
relevant studies were included?

19. 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

20. Question 4
Did the review’s authors do
enough to assess the quality of
the included studies?

21. RCT checklist

22. 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?

23. Question 5
If the results of the review have
been combined, was it reasonable
to do so?

24. 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?

25. Question 6
What are the overall results of the
review?

26. How are the results presented?
• Number needed to treat (NNT)
• Odds Ratio
• Relative risk
• Mean difference

27. 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

28. 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

29. Forest plots
more than 1less than 1 1

30. Forest plots
more than 1less than 1 1
Line of no effect

31. Forest plots
more than 1less than 1 1
Line of no effect

32. Forest plots
more than 1less than 1 1
Line of no effect
Best estimate

33. Forest plots
more than 1less than 1 1
Line of no effect
Best estimate
Confidence interval

34. Forest plots
more than 1less than 1 1
Line of no effect
Best estimate
Confidence interval

35. Forest plots
more than 1less than 1 1
Line of no effect
Best estimate
Pooled result
Confidence interval

36. Question 7
How precise are the results?

37. Confidence intervals
Practical exercise

38. 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

39. Question 8
Can the results be applied to the
local population?

40. 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

41. Question 9
Were all the important outcomes
considered?

42. 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?

43. Question 10
Are the benefits worth the harms
and the costs?

44. Benefit v harms and costs
• How significant are the
benefits?
• Is there any discussion of
possible side effects etc.?
• Are financial costs
mentioned?

45. Summary
Validity
Is it
trustworthy?
Results
What does
it say?
Relevance
Will it help?

46. Qualitative research

47. 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

48. Components of qualitative research
Research question
Sampling process
Data collection
Data analysis

49. Question 1
Was there a clear statement of
the aims of the research?

50. The research question
• Describes why the research is being
carried out
• Qualitative research addresses the
questions
• Are the aims of the research clear?

51. Question 2
Is a qualitative methodology
appropriate?

52. 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

53. Question 3
Was the research design
appropriate to address the aims of
the research?

54. Research methodologies
phenomenology
field
research
grounded
theory
action
research
ethnography

55. Question 4
Was the recruitment strategy
appropriate to the aims of the
research?

56. Sampling
• Sample size can be determined by
– Data analysis
– Time constraints
• What population does the sample refer
to?
• How was the sample selected?

57. Sampling
Methods of sampling:
• Convenience
• Purposive
• Quota
• Snowballing

58. Question 5
Was the data collected in a way
that addressed the research
issue?

59. Data collection
• Are the methods the most suitable for
the research question?
• Are the methods explicit?
• Is the venue clearly described?

60. Question 6
Has the relationship between
researcher and participants been
adequately considered?

61. Reflexivity and researcher bias
VenueArea being
studied
Types of interview
questions asked
Meaning given
to data

62. Question 7
Have ethical issues been taken
into consideration?

63. Ethics
Need to consider:
• Consent
• Confidentiality
• Professional responsibility
• Reporting
• Ethics committee approval

64. Question 8
Was the data analysis sufficiently
rigorous?

65. Data analysis
• Description of analysis
• Clarity of approach
• Use of all the data
• Potential for bias

66. Question 9
Is there a clear statement of
findings?

67. 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?

68. Triangulation
questionnaire professionals

69. Question 10
How valuable is the research?

70. Value of the research
Consider your appraisal of the paper in
terms of:
• Credibility
• Dependability
• Transferability
• Confirmability
How useful is the paper to you?

71. Questions to ask

72. Running a critical
appraisal workshop

73. 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

74. Structuring the session
• Dependent on the group and time frame
• Presentation
• Encourage audience participation
• Use interactive activities
• Practical critical appraisal in groups
• Feedback

75. 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

76. Any
Questions?
The end!
Paula Funnell
Faculty Liaison Librarian (Medicine & Dentistry)
Queen Mary University of London
p.a.funnell@qmul.ac.uk