You need to carefully choose the review type that will match the purpose and scope of your research.
It is vital you have a clear understanding of what is involved when undertaking a particular type of review.
Follow relevant standards and adhere to best practice methods as outlined in this guide.
|Scoping review||Systematic review||Narrative (literature) review|
What is it?
|Rapid gathering of literature in a given policy or clinical area where the aims are to accumulate as much evidence as possible and map the results to provide an overview of the type, extent and quantity of research available on a given topic.||Attempts to identify, appraise and synthesise all empirical evidence that meets prespecified eligibility criteria to answer a given research question. Uses explicit, reproducible methods aimed at minimizing bias, to produce reliable findings and inform decision making.||Synthesises the findings of literature retrieved from searches of computerised databases, hand searches, and authoritative texts.|
|Why do it?||To capture breadth instead of depth of literature; identify gaps within the research area; occasionally used as a precursor to a systematic review.||To address a clearly focused review question by finding the best available, relevant research studies and synthesising the results.||To set the scene for the research, often as part of a bigger project/thesis.|
|Question||Often broad e.g. trying to find out what is already known about a topic. However, there is also scope to have a preconceived question to assess what literature is available around the subject.||Focused on a single topic.||May start with a clear question to be answered, but they more often involve general discussion of a subject with no stated hypothesis; i.e. a topical approach.|
|Sources/search||Ideally, a protocol or plan is included. Clear objectives are identified. Comprehensive sources and explicit and reproducible search strategy. Use of a wide range of resources, including black and grey literature, of any study type.||
A peer reviewed protocol or plan is included. Clear objectives are identified. Comprehensive sources and explicit and reproducible search strategy.
Use of a wide range of resources, including black and grey literature. Often a focus on randomised controlled trials.
|Does not attempt to locate all relevant literature in a systematic, reproducible way. Search strategy, if presented, may be described in broad terms.|
Eligibility criteria are clearly defined before the review is conducted but may be revisited throughout the review. Due to the iterative nature of a scoping review, some changes may be necessary.
|Eligibility criteria are clearly defined before the review is conducted.||Not usually used or applied as database limits.|
|Selection/screening||Often broad - may differ depending on resources found. Criterion-based selection is uniformly applied, clear and explicit.||Criterion-based selection is uniformly applied, clear and explicit.||Not specified, or ad hoc.|
|Appraisal||Variable - typically not done, or done in narrative form.||Rigorous critical appraisal, and evaluation of study quality.||Expected to demonstrate a critical approach to interpretation of research findings but not done in a systematic, reproducible manner.|
|Synthesis||Depends on the purpose, usually a descriptive summary (tabulation is optional).||Clear summaries of studies based on high quality evidence. May include a meta-analysis.||Often descriptive summary.|
|Inferences||Evidence-based.||Evidence-based.||Subjective, possibly evidence-based.|
Acknowledgements: Dr Maureen McEvoy, Dr Steven Milanese, Dr Saravana Kumar, and Dr Craig Phillips, University of South Australia.