What is a Scoping Review?

A scoping review is designed to map the existing literature in a particular topic or research area. Unlike systematic reviews, which address specific research questions with a precise methodology, scoping reviews are broader in their methodology. They aim to provide an overview of the available research evidence, identify key characteristics, and highlight gaps in the current knowledge. The scoping review methodology helps understand emerging evidence and the breadth of information on a new or poorly defined topic.

Scoping reviews search, select, and synthesize existing literature but allow for greater flexibility. The scoping review process clarifies working definitions and conceptual boundaries. It provides a preliminary assessment of the size and scope of available research literature. Scoping review methods can identify gaps in the research and suggest areas for future research priorities. This approach is valuable in fields where research is developing or where there is a significant amount of disparate information to be synthesized.

When to use a scoping review?

Scoping reviews are used in several fields, especially within the health sciences and social sciences. They are ideal when exploring new or complex research areas where the evidence may be sparse or varied. It is useful to conduct a scoping review when the research question is exploratory and not limited to specific interventions or outcomes, providing a comprehensive overview of the relevant literature.

This type of review is also valuable for identifying gaps in the existing literature that can inform future research agendas. In health research policy, for example, scoping reviews can map out the range of interventions available for a particular health condition, helping policymakers understand the current state of evidence. Conducting a scoping review is useful in social research methodology for exploring how different concepts are being used across various studies.

Scoping reviews tend to be used when the goal is to identify gaps in the research evidence and suggest areas for future research. They can inform future research priorities by highlighting areas where evidence is lacking. Additionally, scoping reviews are useful for practitioners who need to stay informed about the latest developments in their field. For instance, a healthcare provider might use a scoping review to understand the range of treatments available for a condition they frequently encounter. This may be followed by a more precise systematic review. Similarly, policymakers might rely on scoping reviews to guide decisions about funding and resource allocation in public health initiatives.

Examining emerging evidence is a critical aspect of conducting scoping reviews. This process involves evidence synthesis, which aggregates findings from various sources to provide a clearer understanding of a particular topic. Scoping reviews are particularly effective for examining emerging evidence because they cast a wide net, incorporating diverse studies and methodologies to create a broad overview of the existing research landscape.

How do scoping reviews differ from other reviews?

Scoping reviews differ from other review types in several ways. They aim to provide an overview of the available research rather than answering specific research questions, making their scope and purpose more exploratory. Unlike traditional systematic reviews that require rigorous and transparent methods to evaluate the quality of evidence, scoping reviews allow for more flexibility in methodology. This flexibility is useful when dealing with emerging evidence or complex topics.

The outcomes of a scoping review are descriptive and focused on identifying key characteristics, gaps, and conceptual boundaries within the body of literature. They include various study designs and methodologies, encompassing qualitative, quantitative, and mixed-methods research. This inclusivity allows for a comprehensive understanding of the topic and makes scoping reviews valuable for mapping the breadth of literature on a given topic.

Scoping reviews also differ in their approach to quality appraisal. While a precise systematic review often includes a critical appraisal, scoping reviews do not typically engage in this level of scrutiny. Instead, they focus on providing an overview of the existing literature, regardless of the quality of the individual studies. This approach includes more studies and can provide a more comprehensive picture of the research landscape. A hybrid approach is to conduct a systematic scoping review which rigorously maps and synthesizes a broad range of literature to identify key concepts, gaps, and trends within a specific field of study.

How to conduct a scoping review?

The common process for conducting scoping reviews is based on the methodological framework developed by Arksey and O'Malley (2005) and refined by Levac, Colquhoun, and O'Brien (2010). These foundational sources offer a comprehensive guide emphasizing transparency, systematic methodology, and iterative processes. By adhering to these guidelines, scoping reviews are thorough and valuable for mapping existing literature and identifying research gaps. Here are the detailed steps involved in conducting a scoping review based on this framework:

1. Define a clear and broad research question: This question should be used to map out the existing literature rather than answer a specific question. When developing the research question, it's important to consider the scope and focus of the review. The question should be broad enough to encompass the full range of relevant literature but specific enough to provide meaningful insights. For example, instead of asking "What is the impact of exercise on health?" a more focused question might be "What is the impact of aerobic exercise on cardiovascular health in adults?"

2. Develop a review protocol: Outline the methods and procedures you will follow in a detailed protocol. This protocol should include objectives, inclusion criteria, search strategy, and data extraction methods. Having a predefined protocol ensures transparency and replicability in your scoping review process.

3. Assemble a review team: Form a team with diverse expertise to enhance the review's comprehensiveness. Although scoping reviews can be completed by a single person, having different perspectives can improve the depth and quality of the review, ensuring that all relevant aspects of the literature are considered.

4. Search for literature: Searching multiple databases like PubMed, Scopus, and Web of Science is crucial for capturing a wide range of relevant literature. Use different keywords and vocabulary specific to the topic. Use boolean operators and search filters to refine your search results.

5. Screen titles and abstracts: Review titles and abstracts to identify studies that meet the inclusion criteria. This initial screening helps narrow down the pool of potentially relevant studies.

6. Full-text review: Conduct a full-text review of the selected studies to confirm their relevance. Document reasons for excluding studies at this stage to maintain transparency.

7. Extract data: Create a standardized data extraction form to collect information. This includes author, year of publication, study design, population, interventions, and outcomes. Consistency in data extraction is crucial for a reliable synthesis.

8. Synthesize evidence: Synthesize the extracted data in a primarily descriptive manner. Summarize key findings, identify patterns, and map out main concepts and gaps in the literature. Visual tools like charts and tables can help present the results. Refer to published scoping reviews for examples of effective data synthesis.

9. Iterative review: Be prepared for an iterative process. As you analyze the data, you may need to revisit the search strategy and selection criteria to refine your review. This iterative approach ensures that your review remains comprehensive and accurate.

Conclusion

Scoping reviews represent a valuable approach for mapping the breadth of literature on a given topic. They are used for exploring new or complex research areas and identifying gaps in existing knowledge. Writing a scoping review involves a systematic but flexible approach, from planning and conducting a comprehensive literature search to synthesizing and presenting the findings.

Scoping reviews play a critical role in the research process, particularly in fields where the evidence base is rapidly evolving. They help researchers, practitioners, and policymakers make informed decisions and identify key areas for future research. By providing a clear overview of the current state of research, scoping reviews pave the way for advancements and innovations in various fields.

References

1. Arksey, H., & O’Malley, L. (2005). Scoping studies: towards a methodological framework. International Journal of Social Research Methodology, 8(1), 19–32. https://doi.org/10.1080/1364557032000119616

2. Levac, D., Colquhoun, H., & O'Brien, K. K. (2010). Scoping studies: Advancing the methodology. Implementation Science, 5, 69. doi:10.1186/1748-5908-5-69

3. Peters, M. D. J., Godfrey, C. M., Khalil, H., McInerney, P., Parker, D., & Soares, C. B. (2015). Guidance for conducting systematic scoping reviews. International Journal of Evidence-Based Healthcare, 13(3), 141-146. doi:10.1097/XEB.0000000000000050

4. Tricco, A. C., Lillie, E., Zarin, W., O'Brien, K. K., Colquhoun, H., Levac, D., ... & Straus, S. E. (2018). PRISMA extension for scoping reviews (PRISMA-ScR): Checklist and explanation. Annals of Internal Medicine, 169(7), 467-473. doi:10.7326/M18-0850