A narrative or literature review is a summary of the current published material on a topic with the aim to deepen the understanding in that research area. This type of review is not as rigorous as others in the review family, comprehensiveness and timeframe can vary and the level of evidence of the studies may not be as important. It can be used to answer multiple questions on a broad topic and does not have a strict protocol to follow.
Purpose: Used for exploratory or broad research questions, emerging topics, to inform further research.
A systematic review is a rigorous and comprehensive synthesis of existing research on a well-defined research question. This type of review is conducted according to strict methodology to minimise risk of bias, and ensure transparency and reproducibility.
A systematic review is the most time intensive out of all the review types, typically taking 12-18 months to complete.
Systematic reviews may also include a meta-analysis. A meta-analysis statistically combines the results of quantitative studies to provide a more precise effect of the results which are presented in a graphical or tabular format.
Purpose: Summarise all available research to answer a specific question, inform clinical decision making and evidence based practice, and identify gaps in research.
Scoping reviews systematically and transparently identify research evidence on a broad topic or set of research questions. Scoping reviews can use qualitative, quantitative, or mixed methods approaches.
The scoping review process is similar to that of systematic reviews in that they are both systematic, transparent and reproducible.
Purpose: To map the scope and size of the available literature, identify gaps in the literature, or inform further research.
This is a "review that opportunistically brings together multiple reviews, conducted to different standards and methods to map and synthesise an existing evidence base." (Sutton, A., Clowes, M., Preston, L., & Booth, A. 2019)
An umbrella review "brings together multiple pre-existing reviews, all conducted using a shared methodology (e.g. Cochrane reviews), facilitating comparison and analysis."
A rapid review provides a quick summary of the evidence available on a particular topic for groups such as healthcare providers, policy makers, and funders. While the methods are still systematic, the process is sped up by simplifying or omitting steps from the standard systematic review process. The process must still be clearly reported by the authors.
Purpose: Rapid reviews are useful for urgent clinical queries, policy planning and time-critical decision making.
The review guide and article links above will be helpful in deciding which review type is most suitable for your research. However, there are also some tools available to help you with your decision: