The purpose of a systematic review is to answer a clear, focused, and answerable question. The question should be the first thing you define in the process of beginning your systematic review and should guide decisions around your inclusion and exclusion criteria, how you create your search strategy, how you collect data and how you present your findings.
PICO(S) is a tool commonly used in medical and health research to help researchers formulate a well-defined question.
|P = Population/patients||
The patient, problem, or population.Ask: How would I describe a group of patients similar to mine?
|I = Intervention||
Therapy, prevention, test, exposureAsk: Which main interventions am I considering?
|C = Comparison||Ask: What is the main alternative?|
|O = Outcome||Ask: What could this intervention accomplish, measure, improve or affect?|
|(S) = Study Design||Ask: what study design is most appropriate to answer the question?|
You must write a systematic review protocol how you plan to conduct your review. The protocol should include the rationale for the systematic review, key questions broken into PICO components, inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence.
Registering your systematic review protocol promotes transparency, reduces the potential for bias, and helps to avoid duplication of reviews.
PLoS Medicine Editors. Best Practice in Systematic Reviews: The Importance of Protocols and Registration PLoS Med. 2011 Feb;8(2):e1001009.
PROSPERO is an international database of prospectively registered systematic reviews in health and social care. Key features from the review protocol are recorded and maintained as a permanent record. PROSPERO aims to provide a comprehensive listing of systematic reviews registered at inception to help avoid unplanned duplication and enable comparison of reported review methods with what was planned in the protocol.
The Cochrane Collaboration publishes protocols as does the journal Systematic Reviews. Many health care journals are publishing protocols now too; see, for example, the following protocols listed in PubMed.