About Systematic Reviews
The Difference Between
Systematic Reviews and Scoping Reviews
Systematic reviews use rigorous and transparent methods to summarize all available eligible evidence on a certain topic as a way to answer a specific research question. To know more about how to write a systematic review, read on at the link. Systematic reviews are widely used tools in evidence-based clinical practice. Scoping reviews, on the other hand, are a relatively new approach in evidence synthesis. Although they are similar to systematic reviews in that they follow a structured protocol, they are conducted for different reasons and have key methodological differences. Scoping reviews are mostly conducted to identify knowledge gaps, study a body of literature, and clarify and investigate concepts. All this is done while taking the research scope of the included studies into account.
Let’s look at the differences between systematic reviews and scoping reviews in further detail.
Differences in Indications for Conducting a Systematic review Vs a Scoping review
According to the Cochrane handbook, systematic reviews use explicit and transparent methods that are selected with the intended purpose of minimizing bias and producing results that are robust and reliable, from which conclusions can be drawn and decisions made . Systematic reviews are considered the pillar of evidence-based healthcare  and are also used to develop trustworthy clinical guidelines [3,4].
Some of the key indications to conduct systematic reviews are:
- To uncover all available international evidence on a certain topic, within the constraints of the scope of the study.
- To confirm or refute the current clinical practice
- Address any variation that exists among existing practices
- Identify new practices based on the available evidence
- Produce guidelines for clinical decision-making and policy development.
Despite the benefits of using systematic reviews, certain objectives cannot be addressed unless there is a preliminary searching and scoping activity to inform the conduct of a systematic review. This led to the emergence of scoping reviews. As their name suggests, scoping reviews are effective tools to determine the scope, or coverage, of a body of literature on a given topic. They provide clear information about the volume and nature of studies available in a specific research area.
Some of the key indications for conducting a scoping review are;
- Identify and map all the available evidence on a given topic .
- To clarify key concepts and definitions
- To examine how the research is being carried out in a certain field
- As a precursor to a systematic review
- To identify and inform knowledge gaps in research
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Methodological Differences between a Systematic Review And A Scoping Review
Both systematic reviews and scoping reviews use a pre-defined systematic approach to synthesize evidence. However, there are certain key differences in the methodology followed in both. Let’s look at these in further detail:
Formulating The Research Question
Systematic reviews attempt to answer focused clinical questions of high importance such as the effectiveness of a certain practice in the treatment of an illness. The PICO (Population, Intervention, Comparison, and Outcome) approach is usually taken to formulate the research question. A scoping review, on the other hand, answers questions with a broader “scope” and correspondingly more expansive inclusion criteria. It is recommended to use the PCC (Population, Concept, and Context) mnemonic to guide the question development .
Risk of Bias Assessment
A scoping review does not aim to produce a critically appraised and carefully synthesized answer to a specific clinical question. Due to this, in a scoping review, the risk of bias assessment of each of the individual studies is generally not performed (unless there is a specific requirement) . When the aim is to determine the extensiveness or scope of existing literature on a certain topic, the aspect of whether or not the literature is of high or low quality becomes a secondary concern.
Synthesis of Findings
As a scoping review is a more exploratory approach to understanding a certain topic, the findings are synthesized as a summary of the individual studies. In a systematic review, statistical methods such as meta-analysis are used to synthesize quantitative evidence (for quantitative effectiveness, diagnostic accuracy, or prevalence or incidence). 
Reviewers should carefully examine the indications mentioned above for each review type when deciding which approach to take. The decision would depend on the type of research question they are asking and the objectives of their research.
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- Munn, Z., Stern, C., Aromataris, E. et al. What kind of systematic review should I conduct? A proposed typology and guidance for systematic reviewers in the medical and health sciences. BMC Med Res Methodol 18, 5 (2018). https://doi.org/10.1186/s12874-017-0468-4
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