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Defining a Researchable
Question: the PICOS Approach
Cochrane Reviewers’ Training Workshop
January 22-23, 2009
Session Presenter: Marcus Vaska
Slides adapted from “Defining a Researchable Question..” by
Miranda Cumpston, with additions and deletions by Dr. Roger
Thomas; “Review Protocol and Designing Your Research Question,”
by the Cochrane Collaboration
Session Goals
Learn about strategies/tips used to help
design a research question
Learn about the PICOS approach, and be
able to apply this method when defining your
own researchable question
Strategies/Tips for Designing a
Research Question
Main Objective: summarize the question in order to help the reader understand the evidence and/or make a practical decision about a health care decision
Remember: Remain neutral, not biased (do not impose own values and/or
preferences when defining your research question)
Although you may be an expert in your particular subject area, don’t assume your readership is. Therefore, the Cochrane review needs to be easy to understand and follow by a person who may have only marginal knowledge about the topic.
A Brief Note on
Cochrane Review Titles
All Cochrane titles and reviews of diagnostic tests utilize one of the following standard formats: <intervention> for <health problem>
i.e. <antibiotics> for <tuberculosis>
<intervention A> vs. <intervention B. for <health problem> i.e. <modern medicine> vs. <traditional, homeopathic
remedies> for <malaria>
<intervention> for <health problem> in <participant group/location> i.e. <education programs> for <AIDS> in
<pastoralist/nomadic societies>
Sample Topic for
Demonstration Purposes
In lieu of traditional homeopathic remedies,
can the administration of modern
medicine help alleviate the malaria
epidemic among children in Africa?
The PICOS Approach:
What is it and Why is it Important?
PICOS = a framework designed to make the process of defining and designing a research question easier
Why is it Important? To create a clear question
To identify the information needed to answer that question
To translate the question into searchable terms
To develop and refine the search approach
“It looks easy. It can be tricky. It is absolutely invaluable.”
[Evidence-Based Answers to Clinical Questions for Busy Clinicians. (2006). The Centre for Clinical Effectiveness, Monash Institute of Health Services Research, Melbourne, Australia, p. 2]
The PICOS Approach
P Population, Patient
I Intervention
C Comparison
O Outcome
S Study Design
P = Population/Patient
When defining this question component, consider the following patient characteristics:
Disease/condition, including the duration, localization, and type of symptoms
Age
Gender
Setting
Standard Diagnostic Criteria
Sample: Modern Medicine for
Treating Malaria
P (Population,
Patient)
Who are the
patients? Who is
affected? Any
exclusions?
Describe the
specific patient
population
characteristics
and/or context of
the disease
Children in Africa
(excluding
adults) suffering
from malaria
P (Population/Patient)
Considerations to Remember
Restrictions on populations/settings
should be based on a sound rationale –
important for Cochrane reviews to be
globally relevant
I = Intervention
When deciding on the intervention(s) that
will be present in a systematic review,
the following should be explicitly
described:
Type of intervention
Intensity of intervention
Frequency of intervention
Duration of intervention
Sample: Modern Medicine for
Treating Malaria
I (Intervention) What is being
done? What
interventions
should be
evaluated?
Define the
intervention!
Modern medicine
(antibiotics)
I (Intervention)
Considerations to Remember
Interventions can consist of: treatment,
diagnostic/screening test, exposure, or
prognostic factor
Should all variations be included?
How will co-interventions, or trials that
only include part of an intervention be
handled?
C = Comparison
Main alternative being considered
Intervention should be explicitly defined
Placebo
Standard therapy
No treatment
Another treatment
Usual care (“the gold standard”)
Sample: Modern Medicine for
Treating Malaria
C
(Comparison)
What is the
alternative to the
intervention? How
effective are
different
interventions?
Traditional
medicine
(homeopathic
remedies)
C (Comparison)
Considerations to Remember
Control groups
Inactive Control
Active Control
O = Outcome
When determining the desired/expected
outcomes of a systematic review, it is key to
consider the following:
Explicit outcome measures and tools
Standardized, validated, established outcome
measures appropriate for the disease condition
Focus on outcomes that are important to patients
Side effects (if known) should be included
Timing of outcome measures should be described
Sample: Modern Medicine for
Treating Malaria
O (Outcome) What are the
relevant
outcomes? What
do you want to
accomplish,
measure,
improve? Define
specific outcomes
Malaria
prevention, death
reduction
O (Outcome)
Considerations to Remember
Include all important outcomes (primary
and secondary)
Include adverse effects
Consider Economic Data
Do Not Include an outcome that is trivial
or meaningless to decision makers!
S = Study Design
The type of study design utilized is
dependent on the type of question
defined. The presence of bias with
different designs should be considered
before deciding which one is most suited
to the question being pondered
Source: Glossary of Terms in the
Cochrane Collaboration Version 4.2.5
May 2005
Types of Study Designs
(Interrupted) Time Series A research design that collects observations at multiple time
points before and after an intervention (interruption). The design attempts to detect whether the intervention has had an effect significantly greater than the underlying trend.
Case-Control Study A study that compares people with a specific disease or
outcome of interest (cases) to people from the same population without that disease or outcome (controls), and which seeks to find associations between the outcome and prior exposure to particular risk factors. This design is particularly useful where the outcome is rare and past exposure can be reliably measured. Case-Control studies are usually retrospective, but not always
Source: Glossary of Terms in the
Cochrane Collaboration Version 4.2.5
May 2005
Types of Study Designs
(continued)
Cohort Study An observational study in which a defined group of people
(the cohort) is followed over time. The outcomes of people in subsets of this cohort are compared, to examine people who were exposed or not exposed (or exposed at different levels) to a particular intervention or other factor of interest
Randomized Controlled Trial (RCT) An experiment in which two or more interventions, possibly
including a control intervention or no intervention, are compared by being randomly allocated to participants. In most trials one intervention is assigned to each individual but sometimes assignment is to defined groups of individuals (for example, in a household) or interventions are assigned within individuals (for example, in different orders or to different parts of the body)
Sample: Modern Medicine for
Treating Malaria
S (Study
Design)
What is the best
study design to
answer the
question ?
Therapy =
prospective RCT;
Prevention =
RCTCohort
StudyCase
Control
S (Study Design)
Considerations to Remember
Most reviews use RCT’s as a threshold
(RCTs are considered the least biased
form of evidence)
Cochrane and Campbell collaborations
may also take evidence from interrupted
time series
Class Exercise
Topic: Interventions to increase influenza
vaccination rates of the elderly in the
community and in institutions
Exercise: Interventions to Increase
Influenza Vaccination Rates
P (Population,
Patient)
Who are the
patients? Who is
affected? Any
exclusions?
Describe the
specific patient
population
characteristics
and/or context of
the disease
Age=adults, elderly,
seniors, NOT
children, NOT
adults <60)
Gender= male &
female
Setting=institution
(hospital, care centre)
vs. community
(home, public place)
Disease/Condition =
influenza
Exercise: Interventions to Increase
Influenza Vaccination Rates
I (Intervention) What is being
done? What
interventions
should be
evaluated?
Define the
intervention
Patient
interventions;
Administrative
interventions;
Health care
workers (HCW)
interventions;
Societal
interventions
Exercise: Interventions to Increase
Influenza Vaccination Rates
C
(Comparison)
What is the
alternative to the
intervention? How
effective are
different
interventions?
No alternative
intervention, other
than to observe the
effectiveness of
different interventions
Comparison of
influenza rates,
illness, mortality
Exercise: Interventions to Increase
Influenza Vaccination Rates
O (Outcome) What are the
relevant
outcomes? What
do you want to
accomplish,
measure,
improve? Define
specific outcomes
Effects of
interventions on
both immediate
and long-term
changes in
influenza
vaccination rates,
and on outcomes
of interest
Exercise: Interventions to Increase
Influenza Vaccination Rates
S (Study
Design)
What is the best
study design to
answer the
question ?
RCTs