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Systematic review guide

A step by step guide to doing a systematic review

Question frameworks

If you are trying to focus a question, frameworks can be used to help draft a question, providing a structure to organise the components of a balanced and focused research question.

The frameworks consist of acronyms which you can use as prompts to help you define your question and consider key areas such as population, intervention and comparisons.

PICO framework

PICO is a framework used in research to develop a searchable clinical question by producing key terms - it especially suits research focused on an intervention or effectiveness of an intervention.

  • P stands for Population (or Problem or Patient): Who are you trying to help, what problem are you trying to solve, which disease are you looking at?
  • I stands for Intervention, which can be a treatment, procedure, diagnostic test or factor. It can include individual patient care or population health activities such as screening for breast cancer.
  • C stands for Comparison or Control and is useful if your question is comparing interventions. There can be an implied comparison as well, for example, the Placebo effect. Sometimes this section will be classed as ‘non applicable’ if the research question does not include a comparison for the intervention.
  • O stands for Outcome which describes what you want the effect of the intervention to be.

As an example, if your research question was "Is aspirin suitable for preventing cardiovascular disease in diabetic patients?"
The PICO elements would be:

  • P: diabetic patients 
  •  I: aspirin 
  • C: not applicable as we not comparing aspirin with anything
  • O: prevention of cardiovascular disease

Other review frameworks

PiCO (population, phenomena of interest, context)
To investigate the experience or meaningfulness of a particular phenomenon

"What is the experience of undergoing high technology medical imaging (such as MRI) in adult patients in Scotland"

PICOC (population, intervention, comparator(s), outcomes, context)
"What is the cost effectiveness of self-monitoring of blood glucose in type 2 diabetes mellitus in high income countries?"

CoCoPop (condition, context, population)

"What is the prevalence or incidence of claustrophobia in adult patients undergoing MRI?"

PIRD (population, index test, reference test, diagnosis of interest)

"What is the diagnostic test accuracy of the Malnutrition Screening Tool, compared to the Patient Generated Subjective Global Assessment, among patients with colorectal cancer to identify undernutrition?"

PEO (population, exposure, outcome)

"Are adults exposed to radon at risk for developing lung cancer?"

PICo (Population, intervention or phenomena of interest, context)

"What are the policy strategies to reduce maternal mortality in pregant and birthing women in Cambodia, Thailand and Sri Lanka?"

PFO (population, prognostic factors or models of interest, outcome)

"In adults wtih low back pain, what is the association between individual recovery expectations and disability outcomes?"

SPICE (setting, population/perspective, intervention, comparison, evaluation)

SPIDER (sample, phenomenon of interest, design, evaluation, research type)

ECLIPSE (expectation, client group, location, impact, professionals, service)

This information about frameworks on this page has been adapted from: 
Munn, Z., Stern, C., Aromataris, E. et al. What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences. BMC Med Res Methodol 18, 5 (2018). https://doi.org/10.1186/s12874-017-0468-4

This article (particularly Table 1 Types of reviews) has more detail on review types and aims and may help you decide which framework will suit your review.

If your topic does not seem to fit any framework you can modify a model by removing or adding elements. It is  most important that your question is focused, relevant and answerable, has not already been done by someone else - and is achievable with the resources (time, expertise, etc.) available to you.