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2. Critical Appraisal Skills Workshop
find appraise act
to help make sense of evidence about effectiveness
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
3. Questions
• Think about some important
questions you have posed in the
course of your work in health
care - alternatively think of some
decisions you have had to make:
what were the questions behind
these decisions?
• What’s the most common type of
question posed?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
4. Does it work? OR Is it effective?
Question types predominate
But there are others:
• Equitable?
• Efficient?
• Appropriate?
• Accessible?
• Responsive? OR
• How does it work? OR
• Diagnosis/prognosis?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
5. Where do we get our information?
• What sorts of information
do you use?
• How do we know how
truthful (valid) the
information we use is?
• What are the pros and
cons of different types of
information we use?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
6. Influences on commissioning
(or any health care decision)
Professional
advice
Top down
priorities
Patients
DECISIONResearchers
WHO?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
7. Influences on commissioning
(or any health care decision)
Guidelines
Textbooks
Peers
EL’s
White Papers
Surveys
Media
DECISIONJournals
WHAT?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
8. Getting better information
• Many sources of
information
• Should try to obtain the
most truthful (valid)
information
• That is get the “evidence”
to answer a particular
question
• Using critical appraisal
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
9. find appraise act
................ evidence about effectiveness
To help make sense of …......................
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
10. Objectives
Recap on what clinical effectiveness is
Explain the best way to measure effectiveness
Explore why reviews are potentially the most
efficient way to find evidence
Explain some reviews jargon
Show why reviews need to be systematic
Give tips on where to find systematic reviews
Explain how to critically appraise reviews so that
you can spot the systematic ones and apply their
results
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
11. Or put another way ......
• Knowing what you’re
looking for
• Knowing where to
look for it
• Understanding what
you’ve got
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
12. What’s in this for you?
Any user of
information
Any provider
of information
Researchers
& reviewers
APPRECIATE () ()
APPRAISE ()
APPLY
LESSONS
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
13. What is clinical effectiveness?
• Answer to question: Does it work?
• Balance of beneficial and harmful effects
• Generally needs qualification with information on:
– Intervention (what you’re doing)
– Individual/population (who you’re doing it to)
– Outcome (what you’re trying to achieve)
THUS: “Antibiotics are effective” - becomes
• Penicillin by injection is effective in reducing deaths from
meningococcal (bacterial) meningitis in all age groups
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
15. Measuring clinical effects and
effectiveness
Intervention
Population Outcomes
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
16. Measuring clinical effects
BY OBSERVING WHAT HAS HAPPENED
Intervention
Population Outcomes
ANY PROBLEMS (BIAS)?
“Experience”
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
17. Measuring clinical effects
BY CAREFULLY OBSERVING (RESEARCHING)
WHAT HAS HAPPENED
Intervention
Population Outcomes
ANY BIAS?
“Retrospective
observational
research”
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
18. Measuring clinical effects
BY RESEARCHING WHAT HAPPENS AFTER
INTRODUCING A NEW INTERVENTION
Intervention
Population Outcomes
ANY BIAS?
“Prospective
case-series”
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
19. Measuring clinical effects
BY FORMALLY COMPARING WHAT HAPPENS
AFTER INTRODUCING A NEW INTERVENTION
Intervention
Population Outcome
No intervention; placebo; best available
Population Outcome
“Controlled
trial”
ANY BIAS?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
20. Measuring clinical effects
BY COMPARING WHAT HAPPENS AFTER INTRODUCING A
NEW INTERVENTION IN A WAY ENSURING EQUIVALENT
GROUPS AT OUTSETP
o
p
u
l
a
t
i
o
n
Group 1
Group 2
Outcome
Outcome
Intervention
No intervention; placebo; best available
“Randomised controlled trial”
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
21. Grading information - levels
of evidence for clinical effects
O n e stu d y A ll stu d ies
R C T
C O N T R O L L E D
T R IA L
C A S E -S E R IE S
O B S E R V A T IO N A L
R E S E A R C H
E X P E R IE N C E
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
22. Why reviews?
• Higher grade of
information - likely to
provide better evidence
• Reveal new results or
generate new lines of
research
• What problems have
you had finding
research information?
CASPCritical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
23. Why reviews?
• TIME
• skills
• resources
• more time!
Identifying even a small
representative selection of
all available research requires:
Bibliographic
databases ?!?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
24. Why reviews?
• But help
required
– understanding
– finding
– appraising
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
26. Reviews jargon
ODDS RATIO (OR):
Number comparing the effect of intervention
on an outcome against a comparison group
MEANING:
A. OR = 1 number of outcomes in intervention group
same as comparison group
B. OR less than 1, less outcomes in intervention group
C. OR more than 1, more outcomes in intervention group
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
27. Reviews jargon
ODDS RATIO (OR) continued:
Consider an OR as a simple fraction:
Outcomes in intervention group
Outcomes in comparison group
1 death If both groups are the same size,
2 deaths the OR = 0.5, that is less than 1
because there are less outcomes
in intervention group
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
28. Reviews jargon
Type of outcome
VALUE OF OR Adverse outcome
eg deaths
Beneficial outcome
eg stopped smokers
Less than 1
eg 0.5
NEW INTERVENTION
BETTER
NEW INTERVENTION
WORSE
1.0 exactly NEW INTERVENTION
NO BETTER/WORSE
NEW INTERVENTION
NO BETTER/WORSE
More than 1
eg 2.0
NEW INTERVENTION
WORSE
NEW INTERVENTION
BETTER
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
29. 1
Bloggs 1987
Fred 1991
John 1991
Smith 1993
Summary
0.5 2.0
Reviews jargon
“The blobbogram”
BLOBS
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
30. 1
Bloggs 1987
Fred 1991
John 1991
Smith 1993
Summary
0.5 2.0
Reviews jargon
“The blobbogram”
WOBBLE - CONFIDENCE INTERVAL
Which results
are we confident
about?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
31. 1
Bloggs 1987
Fred 1991
John 1991
Smith 1993
Summary
0.5 2.0
Reviews jargon
“The blobbogram”
THE SUMMARY
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
32. Why reviews
need to be systematic
• “Current medical reviews do not
routinely use scientific methods to
identify, assess and synthesise
information.” (Mulrow, 1987)
50 reviews in 4 major journals, 1985-86
• No statement of methods 49
• Summary inappropriate 47
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
33. Why reviews
need to be systematic
Application of scientific principles
• Formulate a question
• Design a means to answer that
question
– search; sift; check; extract; summarise
• Carry out the investigation
• Draw conclusions
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
34. Why reviews
need to be systematic
• In 7 primary care journals
• 28 reviews identified in 1991
• Assessed on 8 criteria (being awarded
up to two points for each - 16 in total)
• Only 7 out of 28 scored 8/16 or more
(Silagy, 1993)
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
35. Why reviews
need to be systematic (& up-to-date)
• Information on best treatments for acute heart
attack were identified from 182 RCTs and
compared with advice in 143 reviews (articles &
textbook chapters) at various times
• “These data have uncovered discrepancies
between the timeliness of recommendations by
clinical experts and the meta-analytic evidence
obtained by pooling RCTs.”
(Antman, 1992)
CASPCritical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
37. Why reviews
need to be systematic (& up-to-date)
“The clinical value of thrombolysis
... remains uncertain.”
Oxford Textbook of Medicine, 1987
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
38. Why reviews
need to be systematic
• PUBLICATION BIAS
• A tendency among investigators, peer
reviewers and journal editors to allow the
direction and statistical significance of
research findings to influence decisions
regarding submission and acceptance for
publication.
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
39.
Finding systematic reviews - where?
• Cochrane library
– Cochrane Reviews
– Database of Abstracts
of Reviews of
Effectiveness (DARE)
– Trials database
• HTA programmes
– HNS
– Wessex IPH
CASPCritical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
40. Finding systematic
reviews - who might help?
• Cochrane library -
BMJ Publications
• NHS Centre for
Reviews &
Dissemination, York
• Regional centres eg
ARIF
• Local medical libraries
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
41. Appraisal checklists for reviews
• Is the review trustworthy / valid?
– Screening questions
– Detailed questions
• What were the review’s results ?
– Role of chance
• How will the results help?
– Relevance
– What else do I need to know?
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP
42. Objectives
Recap on what clinical effectiveness is
Explain the best way to measure effectiveness
Explore why reviews are potentially the most
efficient way to find evidence
Explain some reviews jargon
Show why reviews need to be systematic
Give tips on where to find systematic reviews
Explain how to critically appraise reviews so that
you can spot the systematic ones and apply their
results
Critical appraisal skills
ARIF
University of Birmingham
ACKNOWLEDGEMENT:
This slide series is based on a format originally designed by CASP