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Systematic Reviews: A How-To Guide

Overview of systematic review steps and resources to assist researchers conducting reviews

A. Develop a Research Question

Develop a Research Question:

At this stage in the process, you and your team have identified a knowledge gap in your field and are aiming to answer a specific question. Next, you will develop your research question. Developing your research question is one of the most important steps in the evidence synthesis process.

Formulating a clear, well-defined research question of appropriate scope is key to a successful evidence synthesis. The research question will be the foundation of your synthesis and from it your research team will identify 2-5 possible search concepts. These search concepts will later be used to build your search strategy. 

Use a framework to structure your research question by clarifying the main concepts of your topic you want to focus on. Your topic may not fit perfectly into a framework, just using part of a framework can be sufficient.

The framework you should use depends on the type of topic you will be researching.

The most common frameworks are:

  • PICO (for clinical / quantitative research topics) 
  • PICo, PEO, SPIDER or SPICE  (for qualitative research topics)
  • CLIP or ECLIPSE  (for topics relating to health management, policies, economics)

Please view the chart below for more information.

Source: Frameworks reproduced and modified with gratitude from the University of London: Using a framework to structure your question Research Guide.

Research Question Frameworks

Identify the PICO elements:

(P) Patient, Population or Problem - This may include the primary problem, disease, or existing conditions. Sometimes the gender, age, or race of a patient may be relevant to the diagnosis or treatment of a disease.
(I) Intervention - Which main intervention, prognostic factor, or exposure are you considering? Or what factor may influence the prognosis of the patient - age, co-existing problems, or previous exposure?
(C) Comparison - What is the main alternative to compare with the intervention? 
(O) Outcomes - What are you hoping to accomplish, improve or affect?

Example:  Amongst children how does alternative therapies compare to pain medication for controlling headaches?

P - Children

I - Alternatives to drugs (complementary therapies? changes to lifestyle?)

C - Pain medication

O - Controlling headaches

Extensions to PICO

There are extensions to the PICO framework available which you can use if your topic has additional concepts:

PICOSS stands for study designs. Use framework if you are only interested in examining specific designs of study.

PICOT- T stands for timeframe. Use framework if your outcomes need to be measured in a certain amount of time - e.g. 24 hours after surgery.

PICOC- C stands for context. Use this framework if you are focusing on a particular organization or particular circumstances.

Source: Frameworks reproduced and modified with gratitude from the University of London: Using a framework to structure your question Research Guide.

Identify the PICo elements:

(P) Patient, Population or Problem- Who and/or what is my question focussed on? 

(I) Interest - A defined event, experience, activity or process.

(Co) Context - A setting or distinct characteristics.


Example: What are the experiences of patients with pressure sores who receive treatment at home?

P - Patients with pressure sores

I - Experiences, views, opinions

Co  - Care in the home

Identify the PEO elements:

(P) Population - who is my question focussed on?

(E) Exposure - what is the issue I'm interested in?

(O) Outcomes or themes - what, in relation to the issue, do I want to examine?

Example: The daily living experiences of mothers with postnatal depression

P- mothers

E- postnatal depression

O- experiences of daily living/quality of life

Identify the SPICE elements:

(S) Setting - Where is the study set e.g. in a specific country, community, in a hospital, in a care home etc.
(P) Perspective - From whose perspective is the study done e.g. the patients, the health professionals., the carers etc.
(I) Intervention - What intervention is being examined?
(C) Comparison - Is the intervention being compared with another?
(E) Evaluation - The outcome measures

Example: Amongst those living in long term facilities, what are the attitudes of carers of people with dementia towards reminiscence therapy?

S - long term care facilities

P - carers

I - reminiscence therapy


E - attitudes

Identify the SPICER elements:

(S) Sample - the group of people being looked at, because qualitative research is not easy to generalize, sample is preferred over patient.
(PI) Phenomenon of Interest -  reasons for behaviour and decisions, rather than an intervention.
(D) Design - the form of research used, such as interview or survey.
(E) Evaluation - outcome measures.
(R) Research type - qualitative, quantitative and/or mixed methods.

Example:  What are the experiences of first time parents attending antenatal classes at Island Health?

S - First time parents

PI - Attendance at ante-natal education classes

D - Interviews

E - Experiences

R - Qualitative studies

Identify the elements of CLIP:

(C) Client – who is the service aimed at?

(L) Location – where is the service sited?

(I) Improvement – what do you want to find out?

(P) Professional – who is involved in providing/improving the service?

Example: How can the clinic improve delivery of tele-health services to elderly patients in rural communities?

C - Elderly patients

L - Rural communities

I - How services can be improved

P - Tele-health professionals

Identify the elements of ECLIPS(E):

(E) Expectation - What is the information needed for?
(C) Client Group - Who is the information needed for e.g. health managers, GPs, patients
(L) Location - Where is the client group or service located
(I) Impact - What is the change in the service, if any, which is being looked for? What would constitute success? How is this being measured?
(P) Professionals - What health professionals are involved in the service?
(S) Service - For which service are you looking for information? For example, outpatient services, nurse-led clinics, intermediate care.


Example: Amongst medical students, what is the retention of female students?

E- To find out retention rates

C- School administrators


I- Retention of female students

P- Medical students

S- Physicians

B. Establish Inclusion/Exclusion Criteria

What are Inclusion and Exclusion Criteria?

These are the boundaries that decide exactly what information you want to find in your literature search and allow you to decide which studies should be included or excluded in your results.

Establishing your inclusion criteria should help you to turn your topic into a viable question. When deciding upon your inclusion criteria consider how broad or narrow you wish your question to be. A narrow topic, for example, would be quicker to research but you may have problems finding relevant studies to review.

How to establish your Inclusion and Exclusion Criteria

In order to establish your criteria you will need to define each aspect of your question very clearly to clarify exactly what you wish to focus on and consider if there are any variations you also wish to explore. This is where using a framework such as a PICO helps.

Example:  Amongst children how does alternative therapies compare to pain medication for controlling headaches?

P - Children

I - Alternatives to drugs (complementary therapies? changes to lifestyle?)

C - Pain medication

O - Controlling headaches

For each part of the PICO we would need to clarify what aspects we are most interested in. 

  • The aspects of our topic we decide to focus on will be our Inclusion criteria.
  • The aspects we don't wish to include will be our Exclusion criteria.
P Children Do we want to focus on children from a specific age group, teenagers, and adolescents?
I Alternatives to drugs  What alternatives do we wish to examine? Complementary therapies? Alternative medicines? Changes in lifestyle? All three? If we decide to focus on complementary therapies do we want to examine all therapies or a specific type of therapy like mind body therapy?
C Pain medication Do we want to focus on all drugs that treat headaches or a group of drugs or a specific drug?
O Controlling headaches Do we want to focus on all types of headaches or a specific type such as tension headaches or migraines?

Also consider: 

  • Location and context – what communities will you focus on e.g. hospitals, general practice etc? Will your study be restricted to a specific geographical area? 
  • Publication date- how far back do you wish to search for information? (For systematic reviews you need to give a reason if you choose to restrict your search by date).      
  • Study design- will your search focus on quantitative or qualitative studies, a mixture of both or a specific type of study such as Randomized Controlled Trials?
  • Scope of studies- will you use studies which only address part of your intervention of interest?; will you use studies that focus on other interventions as well as your own?

Source: Reproduced and modified with gratitude from the University of London: Using a framework to structure your question Research Guide.

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