A systematic review starts with a clearly defined question and uses systematic and explicit methods to identify, select and critically appraise relevant research. A variety of tools are available to break the review question into sections.
The protocol spells out the rationale and methods for a systematic review. It acts as a guide for searches and provides details like the population of interest, study size, location, date range, outcomes etc. It's purpose is to help ensure that results aren't arbitrary.
Step 1. Identify concepts. The following tools might be helpful (more notations are available here)
Clinical questions use PICO – Patient/problem, Intervention, Control, Outcome
Business, commerce, economics use CIMO – Context, Intervention, Mechanism, Outcome
Qualitative and mixed methods use SPIDER – Sample, Phenomenon of Interest, Design, Evaluation, Research type
Qualitative methods use SPICE – Setting, Perspective, Intervention, Comparison, Evaluation
Health policy and management use ECLIPSE – Expectation, Client group, Location, Impact, Professionals, SErvice
Rehabilitation use PESICO – Patient, Environment, Stakeholders, Intervention, Comparison, Outcome
Step 2. Consider synonyms, spelling variants, acronyms, truncation and proximity operators
Step 3. Are search filters for specific research methodologies required?
Step 4. Check search strategy and revise if necessary
Baird, R. (2018). Systematic reviews and meta-analytic techniques. Seminars in Pediatric Surgery, 27(6), 338–344.
Cooke, A., Smith, D., & Booth, A. (2012). Beyond PICO: The SPIDER tool for qualitative evidence synthesis. Qualitative Health Research, 22(10), 1435–1443.
Methley, A. M., Campbell, S., Chew-Graham, C., McNally, R., & Cheraghi-Sohi, S. (2014). PICO, PICOS and SPIDER: A comparison study of specificity and sensitivity in three search tools for qualitative systematic reviews. BMC Health Services Research, 14(1), 579.
Stern, C., Jordan, Z., & McArthur, A. (2014). Developing the review question and inclusion criteria. AJN The American Journal of Nursing, 114(4), 53–56.
Haddaway, N. R. et al. (2018). ROSES RepOrting standards for Systemactic Evidence Synthesis: Pro forma, flow-diagram and descriptive summary of the plan and conduct of environmental systematic review and systematic maps. Environmental Evidence, 7, 7. https://doi.org/10.1186/s13750-018-0121-7
It's a good idea to register your planned systematic review at the outset. This helps avoid duplication and allows others to see your review methods. There are a number of places a review can be registered:
Open Science Framework (OSF) Registries. Register of systematic review protocols.
Prospero: International prospective register of systematic reviews. The main site where health related systematic reviews are registered.