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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
Who are the Children in Africa
P (Population,
patients? Who is (excluding
Patient)
affected? Any adults) suffering
exclusions? from malaria
Describe the
specific patient
population
characteristics
and/or context of
the disease

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

Treating Malaria
I (Intervention) What is being Modern medicine
done? What (antibiotics)
interventions
should be
evaluated?
Define the
intervention!

I (Intervention)
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”)

Treating Malaria
What is the Traditional
C
alternative to the medicine
(Comparison)
intervention? How (homeopathic
effective are remedies)
different
interventions?

C (Comparison)

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


Treating Malaria
What are the Malaria
O (Outcome)
relevant prevention, death
outcomes? What reduction
do you want to
accomplish,
measure,
improve? Define
specific outcomes

O (Outcome)
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

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)
Source: Glossary of Terms in the
Cochrane Collaboration Version 4.2.5
May 2005

Treating Malaria
What is the best Therapy =
S (Study
study design to prospective RCT;
Design)
answer the Prevention =
RCTCohort
question ?
StudyCase
Control

S (Study Design)
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
Who are the
P (Population, Age=adults, elderly,
seniors, NOT
patients? Who is
Patient) children, NOT
affected? Any
adults <60)
exclusions?
Gender= male &
Describe the female
specific patient Setting=institution
population (hospital, care centre)
characteristics vs. community
(home, public place)
and/or context of
Disease/Condition =
the disease
influenza

I (Intervention) What is being Patient
done? What interventions;
interventions Administrative
should be interventions;
evaluated? Health care
Define the workers (HCW)
intervention interventions;
Societal
interventions

No alternative
What is the
C
intervention, other
alternative to the
(Comparison) than to observe the
intervention? How effectiveness of
effective are different interventions
different
interventions? Comparison of
influenza rates,
illness, mortality

What are the Effects of
O (Outcome)
relevant interventions on
outcomes? What both immediate
do you want to and long-term
accomplish, changes in
measure, influenza
improve? Define vaccination rates,
specific outcomes and on outcomes
of interest

What is the best RCTs
S (Study
study design to
Design)
answer the
question ?

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