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Systematic Review Guide

Define your Research Question

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, exposure

Ask: 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?

Writing your PICO Question

Intervention/Therapy Question

In _____________ (P), what is the effect of __________ (I) compared with __________(C) on ___________ (O) ?


Prevention Questions

For ________ (P) does the use of ______ (I) compared with _________ (C) reduce the future risk of ________ (O)?



In patients with acute migraine (P), what is the effect of sumatriptan (I) compared with naproxen (C) on pain relief (O)?


Further Reading:

Buckley DI, Ansari M, Butler M, et al. The Refinement of Topics for Systematic Reviews: Lessons and Recommendations From the Effective Health Care Program. J Clin Epidemiol. 2014; 67:425-432.


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review, key questions broken into PICO components, inclusion/exclusion criteria, literature searches for published/unpublished literature, data abstraction/data management, assessment of methodological quality of individual studies, data synthesis, and grading the evidence.

Standards for Protocols

The "Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement" sets out the standards with a checklist of items to include in your review protocol. See Table 3 of the PRISMA-P 2015 Checklist. 

Protocol Template

Register your Protocol

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.

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