The introduction of the review protocol should provide explicit and comprehensive information regarding the justification (rationale) for the conduct of the review in the context of what is already known. The introduction should be of sufficient length to discuss all of the elements of the proposed plan for the review; usually all the relevant information may be provided in approximately 1000 words. This section should be written in simple prose for non-expert readers. Usually, a systematic review is informed by international research and is conducted for an international readership, therefore, reviewers should include relevant international literature in this introductory section. There are exceptions, for example, where systematic reviews are conducted on a question relevant to a single country (for example, Australia or UK) or region (Africa) specific issues. However, with the exception of these reviews that use strict limitations on the inclusion criteria, a systematic review should include all relevant international literature. The introduction should provide sufficient details to justify the conduct of the review and the choice of inclusion criteria for the review (types of participants, types of interventions and comparators, the types of outcomes, and types of studies). The review protocol should provide all conceptual and operational definitions that are relevant for the review. It is the responsibility of the reviewers to ensure that their review is not a duplicate of an existing review. It is recommended that reviewers search major electronic databases to determine that there have been no recently published systematic reviews on the same topic. A search of the JBI Evidence Synthesis, Cochrane Database, MEDLINE, DARE, PROSPERO, EPISTEMONIKOS, and ACCESSSS will assist to establish whether or not a recent review exists on the topic of interest. Reviewers should report in the background section the details of this preliminary search. If systematic reviews on the topic of interest have already been conducted, reviewers should explain the differences between the existing reviews and the new proposal and provide an explicit justification for the need to conduct a new systematic review.
The introduction should conclude with an overarching review objective that captures and aligns with the core elements/mnemonic of the inclusion criteria (e.g. PICO). The stated objective should clearly indicate what the review project is trying to achieve. Example of a review objective: ‘To synthesize the best available evidence related to using inspiratory muscle training to improve dyspnoea in patients with chronic obstructive pulmonary disease.’ This broad statement provides the general scope but must be further clarified with focused review questions.
The background section of the review protocol should provide information regarding:
- the importance of the topic (prevalence, incidence, morbidity, mortality, impact on quality of life; economic burden),
- concerns expressed by consumers, healthcare professionals, policy-makers,
- the specifics of diverse groups of patients (age, gender, ethnicity, severity of the disease, co-existing diseases) and settings,
- the intervention of interest and how it works,
- any uncertainties and conflicting reports regarding the effectiveness of the intervention of interest,
- other existing interventions with which the intervention of interest may be compared,
- the importance of different outcomes,
- how outcomes are measured (approaches, measurement instruments),
- the relevance of different research study designs in the examination of the topic of interest,
- relevant existing primary research studies,
- what is already known, including details about the existing systematic reviews, including meta-analyses, and
- the justification for the need for a new review and the objectives of the review project.