A systematic review is based on a pre-defined specific research question (Cochrane Handbook, 1.1). Well-formulated questions will guide many aspects of the review process, including determining eligibility criteria, searching for studies, collecting data from included studies, and presenting findings (Cochrane Handbook, 2.1).
The research question should be clear and focused - not too vague, too specific or too broad.
You may like to consider some of the techniques mentioned below to help you with this process. They can be useful but are not necessary for a good search strategy.
Practitioners of Evidence-Based Practice (EBP) often use a specialised framework, called PICO, to form the question and facilitate the literature search.1 The PICO framework guides you to develop an answerable research question that is based on evidence, which helps you ensure that the research question can be translated into search concepts.
| Framework item: | Think about: | Example: |
|---|---|---|
| Patient/Problem or Population |
What are the patient's demographics such as age, gender or ethnicity? Or what is the problem type (disease/condition)? |
Work related neck muscle pain |
| Intervention |
What type of intervention is being considered? For example: drug treatment, exercise or rest? |
Strength training of the painful muscle |
| Comparison (or control) if appropriate |
Is there another treatment to be considered? The comparison may be with another medication, another form of treatment such as exercise or no treatment at all. For example: placebo, standard therapy, no treatment, gold standard. |
Rest |
| Outcome |
What is the desired effect you would like to see? What are you trying to accomplish, measure, improve, affect? For example: reduced mortality or morbidity, improved memory. |
Pain relief |
A variant of PICO is PICOS where S stands for Study designs. It establishes which study designs are appropriate for answering the question, e.g. randomised controlled trial (RCT). There is also PICOC (C for context) and PICOT (T for time-frame). The list below helps you decide which study design matches your question.
Once you have clearly identified the main elements of your question using the PICO framework, it is easy to write your question statement. The table below provides some examples.
|
Question type |
P - Patient, Population or Problem |
I - Intervention or Exposure |
C - Comparison |
O - Outcome |
|---|---|---|---|---|
| Therapy | In patients with osteoarthritis of the knee | is hydrotherapy more effective than | traditional physiotherapy | in relieving pain? |
| Prevention | For obese children | does the use of community recreation activities | compared to educational programs in lifestyle changes | reduce the risk of diabetes mellitus? |
| Diagnosis | For deep vein thrombosis | is D-dimer testing or | ultrasound | more accurate for diagnosis? |
| Prognosis | In healthy older women that suffer hip fractures | within the year after injury | what is the relative risk of death? | |
| Etiology | Do adults | who binge drink | compared to those who do not binge drink | have higher mortality rates? |
1. Schardt, C., Adams, M. B., Owens, T., Keitz, S., & Fontelo, P. (2007). Utilization of the PICO framework to improve searching PubMed for clinical questions. BMC Medical Informatics and Decision Making, 7, 16. doi: http://dx.doi.org/10.1186/1472-6947-7-1
This is a modified version of the PICO framework above, PICo, which can be used for qualitative questions.
|
P |
I |
Co |
|---|---|---|
| Population | Interest | Context |
to search for qualitative studies
|
S |
P |
I |
C |
E |
|---|---|---|---|---|
| Setting (where?) | Perspective (for whom?) | Intervention (what?) | Comparison (compared with what?) | Evaluation (with what result?) |
Booth, A. (2006). Clear and present questions: formulating questions for evidence based practice, Library Hi Tech, Vol. 24 No. 3, pp. 355-368. https://doi.org/10.1108/07378830610692127
to search for qualitative and mixed methods research studies
|
S |
PI |
D |
E |
R |
|---|---|---|---|---|
| Sample | Phenomenon of Interest | Design | Evaluation | Research type |
Cooke, A., Smith, D., & Booth, A. (2012). Beyond PICO: the SPIDER tool for qualitative evidence synthesis. Qualitative health research, 22(10), 1435–1443. https://doi.org/10.1177%2F1049732312452938
to search for the effect of exposure to something e.g. smoky atmosphere
|
P |
E |
C |
O |
|---|---|---|---|
| Population | Exposure | Comparison | Outcome |
Morgan, R. L., Whaley, P., Thayer, K. A., & Schünemann, H. J. (2018). Identifying the PECO: A framework for formulating good questions to explore the association of environmental and other exposures with health outcomes. Environment International, 121 (Pt 1), 1027–1031. https://doi.org/10.1016/j.envint.2018.07.015
|
S |
M |
A |
R |
T |
|---|---|---|---|---|
| Specific | Measureable | Attainable | Relevant | Time-bound |
Granger, B.B. (2020). Life After PICOT: Taking the Next Step in a Clinical Inquiry Project. AACN Advanced Critical Care, 31(1), 92–97. https://doi.org/10.4037/aacnacc2020986
When starting a systematic review, it's a good idea to look in different databases and grey literature sources to see what evidence is available.
Conducting a scoping search allows you to put your research in context and justify its importance, identify any potential 'gaps' in your research area, find any existing systematic reviews, and see if there is enough evidence to write a systematic review.
Resources to help scope your topic and locate systematic reviews:
You can generally find published systematic reviews by searching relevant subject specific databases. You could also check:
You can also register your protocol (see further information below under Develop a protocol) in these databases, selected based on your research topic.
Inclusion and exclusion criteria set the boundaries for the systematic review. They are determined after setting the research question usually before the search is conducted, however scoping searches may need to be undertaken to determine appropriate criteria.
Here is an example of some of the common inclusion/exclusion criteria used in systematic reviews from The University of Melbourne, which include:
Sources: The University of Melbourne Systematic Reviews Library Guide & James Cook University Library Guide
Once the research question is formulated, the research protocol can be developed. This is an important planning document that explicitly describes the methods for the review before any literature searching takes place.
Once you have written your protocol, the next step is to register it online so that it is publicly accessible. This avoids duplication of your research topic by others. There are various sources of protocol registries, some of which are listed above under Scope your topic. It is becoming more common to register or publish scoping review protocols via Open Science Framework (OSF), F1000research, PLOS & BMJ Open.
Sources: University of South Australia Library Guide Protocol for Scoping Reviews & University of Tasmania Library Guide Protocol for Systematic Reviews