Transcript Therapy Studies

EBM Revisited: a brief refresher
Introduction and Description of the
ADEPT Course
Andrew Booth & Marishona Ortega
Why ADEPT?
• librarians need to be able to support
Evidence Based Healthcare
• users need to be able to do their own
focused searching
• only a small proportion (about 1%) of the
medical literature is clinically relevant
The Ingredients of EBM
•
•
•
•
Focused questions
Hierarchy of evidence
Filters
Problem based learning
– Scenarios
– Anatomy of the question
– Shared expertise (SEE-
ONE, DO-ONE,
TEACH-ONE)
Focusing the question
• Helping requester to
break information
need down into EBM
anatomy clarifies the
originating question.
• “OR” within
categories and “AND”
between categories.
Understanding study design
• Adds to your ability to
recognise “good
studies”and “bad
studies”.
• Helps you to identify
the question being
answered by an
article.
Using methodological filters
• One line, sensitive and specific versions
• rely on publication types or occurrence of
textwords to identify methodologically
superior studies
• are also used to compile pre-filtered
database products e.g.. Cochrane Library
(clinical trials), DARE (reviews) & NHS
EED (economic evaluations)
Topics
Types of question primary studies
Types of article secondary
studies
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•
•
•
• Reviews
• Economic Evaluations
• Guidelines
Diagnosis
Etiology
Prognosis
Therapy
[and now Qualitative]
The Process
•
•
•
•
•
•
•
Clinical Scenario
Focusing the question
Translating into MeSH terms
Conducting the literature search
Applying the methodological filters
Filtering for quality studies
Specialist resources
Resources
For each study:
• User Guides from
JAMA
• ACP Journal Club or
EBM MEDLINE
Guides
• CASP filters page
http://www.phru.org.uk/
~casp/filters.htm
About ADEPT:
• Becoming ADEPT:
Project Overview HLR Dec 1997.
• Becoming ADEPT:
delivering distance
learning on EBM to
Librarians - HLR Sept
1998.
Principles of Study Design: a
librarian’s perspective
Andrew Booth
Scenario
You are a postgraduate medical librarian in
Kleptovale NHS Trust. You have bid for a
Nicksnix Library security system. The
postgraduate Dean wants some evidence
that it is effective. There is no published
evidence so you will need to conduct an
original study. What are you going to do?
Lower forms of evidence
• Anecdote (I once knew a librarian
who……)
• Case study
• Case series
Answer. A Case-control study
• You call up the Regional Library Unit.
Details of 10 libraries with book losses of
>5% (cases) and of 10 libraries with losses
of <1% (controls).
• Phone all 20 libraries and ask “Do you use
a library security system?” Yes/No
You compile a 2 by 2 table.
Yes
System
No
System
Total
Yes >5%
No >5%
Total
4
6
10
6
4
10
10
10
20
But........
• Controls might be underreporting their
losses to make system look good.
• People with security systems may be more
security conscious (using other methods)
• Bias (flaw in research method) or
confounding (some other factor not taken
into account).
Case-control studies
[Retrospective]
Advantages
• Quick and cheap
• It’s the only method
for rare events
• Requires fewer
subjects than other
designs
Disadvantages
• Relies on
recall/records
• Open to confounding
• Selection of controls
is difficult
• Potential bias in recall
or selection.
Answer: A Cohort Study
Convince 110 members of HLG to take part
in a prospective cohort study. Over a two
year period you record who uses the
system [Exposed] and who doesn’t [NonExposed]. At end of two years you
calculate rate of heavy losses within both
groups.
Another 2 by 2 table
No.
No. of heavy
losses
Nicksnix 30
3
1/10
Non80
Nicksnix
12
1.5/10
But.....
• OK so you may have eliminated recall and
reporting bias through baseline data
collection, but
• Libraries with security systems may be in
richer areas and less prone to theft
anyway.
Cohort studies
Advantages
Disadvantages
• Subjects can be
matched
• Eligibility criteria can
be standardised
• Easier to run than an
RCT.
• Blinding is difficult
• Randomisation is not
present
• Requires a large
sample and longer
follow up.
Answer: An RCT
• You go for a sponsored Randomised
Controlled Trial. You recruit another group
of HLG members. You randomly assign
half with a free NicksNix system and the
others must go without. After a year you
have the following results.
Yet another 2 by 2 table
No.
No of losses
Nicksnix 100
2
2%
Non100
Nicksnix
2
2%
Finally....
After three years and thirty minutes and
three separate studies the Postgraduate
Dean believes he has the right answer:-
No difference, No Nicksnix,
No comment!!!
Randomised Controlled Trials
Advantages
Disadvantages
• Unbiased distribution
of confounders
• Blinding more
possible
• Randomisation
facilitates statistical
analysis
• Expensive in time and
money
• Volunteer bias
• Ethical problems,
sometimes
• May create artificial
behaviour
Postscript
Practically, you wouldn’t go to all that effort.
Maybe use a cross-over design where one
Library (n-of-1 study) or more went
through periods without and then with a
system. You would need to make sure that
there was a washout period. Also you
would have to guard against a placebo
effect.
Hierarchy of effectiveness
•
•
•
•
Systematic Review
Randomised Controlled Trial
Cohort study [Prospective]
Case-control [Retrospective] (May be
contemporary or historical)
• Case series
• Individual case study
There are other hierarchies
E.g. Hierarchy of patient experience
• Qualitative research study
• Interviews/Surveys
• Case study
• Anecdote
• C.p. Signal to noise ratio (Edwards AG, Russell
LT & Stott NCH (1998) Signal versus noise in
the evidence base for medicine: an alternative to
hierarchies of evidence? Family Practice 15 (4):
319-322)
Constructing a
Question
Marishona Ortega
EBP Process
•
•
•
•
Define problem
Find evidence
Appraise evidence
Apply results of
appraisal
• Evaluate change
• Redefine problem
Formulating a question using
PICO
• Population/Patient/Condition
– Who is the question about?
• Intervention/Exposure
– What is being done to or happening to
the patient/population?
• Comparison(s)
– What could be done instead of the
intervention?
• Outcome(s)
– How does the intervention affect the
patient/population?
Another way of looking
at PICO
Focused Questions the benefits
• Guides search process
• Prompts for considering synonyms
and alternatives
• Saves time - increases relevance
Translating your
question into a strategy
Your department is exploring the idea of
introducing near-patient testing for Group
A ß-Streptococcal throat infection. You
have been asked by your manager to
gather the evidence for this procedure
with particular reference to sensitivity,
specificity and cost.
PICO Applied:
• Patient/Condition
– Group A ß -Streptococcal throat infection
• Intervention
– Near-patient testing or rapid test
• Comparison
– Laboratory testing
• Outcome
– Sensitivity, specificity, cost
Now your turn…
As background to your service you are
compiling information identifying the risks of
infection from HIV, Hepatitis B & C and CMV
following homologous blood transfusion.
How would you structure your search?
Now your turn - contd
• Patient/Population
– Persons receiving blood transfusion
• Intervention
– Homologous blood transfusion
• Comparison
– Another form of blood transfusion i.e. autologous
• Outcome
– Not becoming infected with HIV, Hepatitis B&C or
CMV
EBP Process
•
•
•
•
Define problem
Find evidence
Appraise evidence
Apply results of
appraisal
• Evaluate change
• Redefine problem
Where do I start?
• Develop your question
• Decide on the most appropriate
source(s)
• Divide your search into
‘concepts’
• Think of alternative terms for
each concept
• Search each concept separately
• Combine concepts using
Boolean logic
Therapy Studies:
Design, Terminology and
Filters
Learning Objectives
• Describe the main characteristics of a rigorous
therapy study.
• Recognise some of the terminology associated
with studies of therapy
• Itemise sub-headings associated with treatment
• Avoid common pitfalls associate with searching
for therapy studies
• Utilise the methodological filters associated with
therapy literature searches
What is a therapy study?
• Treatment or management of a condition
– Objective of treatment
– Choice of treatment
– Target of treatment
• Literature-based evidence can assist
with all three aspects, but most
particularly “Choice of treatment”
Therapy Studies
• A search for therapy studies focuses on
the decision between treatment choices
• Therefore the evidence will be
comparative
• The preferred design for a therapy study is
a RANDOMISED CONTROLLED TRIAL
(RCT)
Searching for therapy
studies
Methodological filters 1
1
2
3
4
5
6
7
8
9
10
11
randomized controlled trial.pt.
controlled clinical trial.pt.
randomized controlled trials/
random allocation/
double blind method/
single blind method/
or/1-6
clinical trial.pt.
exp clinical trials/
(clin$ adj25 trial$).ti,ab.
((singl$ or doubl$ or trebl$ or tripl$)
adj25 (blind$ or mask$)).ti,ab.
12 placebos/
13 placebos.ti,ab.
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
random.ti,ab.
research design/
or/8-15
comparative study/
exp evaluation studies/
follow up studies/
prospective studies/
(control$ or prospectiv$ or
volunteer$).ti,ab.
or/17-21
7 or 16 or 22
animal/
human/
24 and 25
24 not 26
23 not 27
Methodological filters 2
Reinhard Wentz:
1
explode clinical trials
2
explode research design
3
randomized controlled trial.pt.
4
clinical trial.pt.
5
(single or double or treble or triple).tw.
6
(mask$ or blind$).tw.
7
5 and 6
8
placebos/ or placebo$.tw.
9
1 or 2 or 3 or 4 or 7 or 8
Methodological filters 3
Mid-range strategy from Health Information
Research Unit, McMaster:
1 randomized controlled trial.pt.
2 or dt.fs.
3 or tu.fs.
4 or random$.tw.
5 or/1-4
And last but not least...
The one-line filter:
clinical trial.pt
• Retrieves 97% of
rigorous therapy studies
• Only includes 3% of
irrelevant studies
So how does this work
in practice?
A 17-year-old female was travelling home one night when
the car her friend was driving careered off the road.
Fortunately, no-one was seriously injured but she
presented to A&E with localised low back pain and was
diagnosed with lumbar strain.
For some time the Senior Physio has been considering the
treatment for low back pain and wonders if acupuncture
might be a more effective and comfortable alternative.
She asks you to run a search to find the relevant
evidence.
What’s your Question?
• Patient/Condition
– 17 year old female with low back
pain/lumbar strain
• Intervention
– Acupuncture
• Comparison
– Existing treatment
• Outcome
– Pain relief
What’s your Strategy?
• Usually start with PATIENT/CONDITION
and then the INTERVENTION
• Thus:
1.
2.
3.
4.
low back pain
acupuncture
1 and 2
limit 3 to clinical trial.pt
Practical Session
Go to:
http://gateway.ovid.com
Username: trainshe
Password: train123
If you need help - just ask!
Feedback time:
How did you get on?!
Filtering for quality studies
Andrew Booth
1. A Comparison
• Drug A versus Drug B
• Drug versus other
(alternative) therapy
• Drug versus placebo
• Service versus
“standard care”
2. Randomisation
• To ensure both
groups are similar
at the beginning
except for the play
of chance
3. Blinding
• Subjects are blinded
• Those delivering
treatment are blinded
• Those doing analysis
are blinded
• Contrast:
Concealment of
allocation
4. Withdrawals and drop outs
• Are all those who
entered into study
accounted for at its
conclusion
• Was an intention to
treat analysis used?
5. Follow up
• Were all participants
followed up and was
data collected in the
same way?
6. Sample size
• Were there enough
participants to
minimise the play of
chance?
Preview of Distance Learning
Module
Andrew Booth
Each module
1. Reading material
2. Worked exercise
3. Exercise with deadline
date
4. Group (Anonymised)
Feedback
Modules
•
•
•
•
Reviews
Diagnosis
(A)etiology/Prognosis
Guidelines/Economic
Evaluations
• Qualitative Research
Contact Us:
Marishona Ortega
• [email protected]
• 0114 222 0797
Andrew Booth
• [email protected]
• 0114 222 0705
Or leave a message with Tricia Campsell
• 0114 222 0703