Scoping Review Methods

Scoping reviews are a powerful type of evidence synthesis used when a research area is complex, heterogeneous, or not yet comprehensively reviewed. Unlike a systematic review, which answers a specific question about effectiveness, a scoping review aims to map the extent, range, and nature of the available evidence on a broad topic. This process helps researchers identify key concepts, theories, sources, and knowledge gaps, ultimately clarifying the landscape to inform future, more focused systematic reviews or primary research studies.

Framing the Scoping Review: Purpose and Rationale

The decision to conduct a scoping review should be intentional and justified. Its primary purposes are distinct from other review types. You would undertake a scoping review to investigate the breadth of evidence on a topic, identify and analyze knowledge gaps in the existing literature, examine how research is conducted on a certain topic (e.g., methodologies used), or to group and clarify key concepts and definitions in a field. A classic rationale is to determine the feasibility and necessity of a future full systematic review by asking, "Is there enough literature, and is it coherent enough, to warrant a detailed systematic review?" By systematically mapping the literature, you create a foundational resource that defines the scope of a body of literature and charts its available evidence.

The Foundational Framework: Arksey and O'Malley

The most widely adopted methodological framework for scoping reviews was established by Arksey and O'Malley in 2005. This framework provides a flexible, iterative roadmap consisting of five core stages: 1) identifying the research question, 2) identifying relevant studies, 3) selecting studies, 4) charting the data, and 5) collating, summarizing, and reporting the results. A sixth stage, consultation with stakeholders, was proposed as optional but is now increasingly considered a valuable component for validating findings and ensuring relevance. The strength of this framework lies in its adaptability; it is not a rigid protocol but a guiding structure that acknowledges the need for refinement as the review progresses, especially when dealing with diverse and complex bodies of literature.

Enhancing Rigor: JBI Methodology and the PRISMA-ScR

To address early critiques about the need for more rigor and transparency, the Joanna Briggs Institute (JBI) developed a detailed, prescriptive methodology that builds upon Arksey and O'Malley's work. The JBI methodology provides explicit guidance for each step, emphasizing an a priori protocol, detailed reporting, and alignment with the research question and objectives. Furthermore, the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) checklist provides a reporting standard. Using the JBI guide and planning to report against PRISMA-ScR significantly strengthens the methodological rigor, reproducibility, and credibility of your review, moving it from an exploratory map to a robust piece of scholarly synthesis.

Executing the Key Stages: From Search to Synthesis

The practical execution of a scoping review is a demanding, systematic process. It begins with formulating a clear, broad research question, often structured using the PCC (Population, Concept, Context) mnemonic recommended by JBI instead of the PICO used for systematic reviews. Developing the search strategy is critical; it must be comprehensive, involving multiple databases and grey literature sources, and is typically designed with a librarian. Study selection follows a transparent, multi-stage screening process (title/abstract, then full-text) against explicit inclusion criteria.

The heart of analysis in a scoping review is data charting. This involves extracting descriptive and contextual data from included sources into a standardized form or table. The charted data might include publication details, country of origin, study population, methodology, key findings, and concepts relevant to your research question. Finally, you collate and summarize results quantitatively (e.g., counting study types, years, geographical distribution) and qualitatively (e.g., thematically grouping concepts, identifying theoretical perspectives, or describing how research is conducted). The output is a structured narrative summary that maps what evidence exists and where the gaps are.

Common Pitfalls

1. Confusing Purpose with a Systematic Review: The most fundamental error is using a scoping review to answer a question about the effectiveness or efficacy of an intervention. This is the domain of a systematic review. If your primary aim is to provide a definitive answer on outcomes, a scoping review is the wrong methodological choice.
2. An Unfocused or Unmanageable Question: While the question should be broad, it must have clear boundaries. A question like "What is known about mental health?" is too vast. Using the PCC framework helps: "What community-based interventions (Concept) exist for adolescent anxiety (Population) in school settings (Context)?" provides a map-able scope.
3. Insufficient Detail in the Data Charting Form: A poorly designed charting form leads to inconsistent, incomplete data extraction. Pilot your form on several diverse studies to ensure it captures all necessary information to address your research question and objectives. This step is crucial for reliable synthesis.
4. Skipping the Critical Consultation Phase: Treating stakeholder consultation as an optional add-on misses a key opportunity. Engaging with experts, practitioners, or patients can help interpret findings, identify missing sources, and ensure the review’s conclusions are meaningful and applicable to the field, thereby increasing its impact.

Summary

• Scoping reviews are designed to map the extent and nature of evidence on broad, complex topics, identifying key concepts, theories, and gaps, rather than to appraise the quality of evidence or answer narrow effectiveness questions.
• The Arksey and O'Malley framework provides the foundational five-stage structure, while the JBI methodology offers detailed, rigorous guidance for enhancing the review's transparency and reproducibility.
• The core process involves formulating a PCC-based question, executing a comprehensive search strategy, systematically selecting studies, and charting data into a standardized form for both quantitative and qualitative analysis.
• The primary outputs are a collated summary of what evidence exists and where significant knowledge gaps lie, which directly informs the need for and focus of future systematic reviews or primary research.
• Adhering to reporting standards like the PRISMA-ScR checklist and incorporating stakeholder consultation are best practices that significantly strengthen the review's credibility and utility.