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Scoping Review

What is a Scoping Review?

A scoping review is a research synthesis designed to map the key concepts, types of evidence, and research gaps on a particular topic. Unlike systematic reviews, which focus on answering a specific research question with a narrow scope and rigorous criteria, scoping reviews are more exploratory and broader. They are often used to:

  • Search existing research on a specific topic
  • Identify key concepts of existing research 
  • Summarize existing research
  • Highlight research gaps for further research

Getting Started: Framing Your Research Question

The foundation of any review lies in a well-defined research question. For scoping reviews, the PCC format (Population, Concept, Context) is often preferred over the PICO(T) format used in systematic reviews. The PCC format allows for broader exploration:

  • Population: Who or what is the focus? This could include specific populations, diseases, or settings.
  • Concept: What is being examined? This could be interventions, phenomena, or trends.
  • Context: Where or in what circumstances does this occur? This might involve geographic locations, healthcare settings, or social contexts.

Scoping Review: The research question is broader and more exploratory, often seeking to map the extent of the literature or understand the range of topics or interventions within a field

  • Example: “What interventions are used to treat hypertension in children, older adults, and pregnant women?”

Systematic Review: Focused on a specific research question, framed using the PICO(T) format (Population, Intervention, Comparison, Outcome, Time).

  • Example: “What is the effect of drug X on blood pressure in adults with hypertension?”

Searching For Other Scoping Reviews

Before starting a scoping review, it’s essential to ensure that your project hasn’t already been completed by someone else. A great place to begin is the Open Science Framework (OSF) database, where researchers register protocols for various types of reviews. Searching OSF and other registries (e.g., PROSPERO, Cochrane and DoPHER) not only confirms that your review will contribute new insights but also provides valuable search strategies from existing reviews. These strategies may include relevant keywords, databases, and other resources that can be adapted to your research when appropriate.

Assembling a Team

Conducting a scoping review requires a collaborative effort. Here’s an outline of key roles:

  • Principal Investigator (PI): Typically oversees the project, ensuring alignment with research goals.
  • Students/Research Assistants: Assist with screening articles, extracting data, and synthesizing findings.
  • Librarian: Plays a critical role in designing and refining search strategies, selecting databases, identifying appropriate MeSH terms and managing references.
  • Subject Matter Expert: Can provide advice about search strategy, sources and key authors.

Developing and Registering Your Protocol

A protocol is a detailed document that outlines the steps of your scoping review, serving as a blueprint for your study. It can be drafted using templates such as the Joanna Briggs Institute template and should record all decisions made before beginning your research, including inclusion and exclusion criteria. University librarians can offer guidance in refining your research question, developing a comprehensive search strategy, and selecting relevant databases. Following best practices, it is recommended to register your protocol on a platform like OSF or publish it in a journal, similar to protocols for systematic reviews.

Selecting Databases

Choosing appropriate databases ensures that the information you retrieve is relevant and of high quality. This selection should align with the focus of the study. Commonly used databases include: 

  • PubMed or Ovid Medline: Ideal for research in medicine and life sciences.
  • Embase: Excellent for healthcare and pharmaceutical studies.
  • CINAHL: Specializes in nursing and allied health topics.
  • PsycINFO: Focuses on psychology and behavioural sciences.
  • Scopus and Web of Science: Great for multidisciplinary topics, offering diverse insights.

Including a multi-disciplinary database alongside a more domain-specific one ensures a broader review of your subject.

Creating a Search Strategy

A well-designed search strategy combines multiple approaches to capture relevant literature effectively.

Inclusion and Exclusion Criteria:

  • Clearly define what will and won’t be included in your search.
  • Inclusion criteria may focus on factors such as population, intervention, study design, or publication language.
  • Exclusion criteria help eliminate irrelevant or lower-quality studies, such as those outside the target timeframe or unrelated to the research question.

Controlled Vocabulary:

  • Use structured thesauri like MeSH (Medical Subject Headings) in PubMed or Emtree in Embase — standardized lists of terms used by databases to index articles.
  • This ensures consistent and precise results, particularly when different studies describe the same concepts using varied terminology.

Free-Text Searches

  • Incorporate keywords, synonyms, and word variations not covered by controlled vocabulary.
  • This broadens the search scope, especially for emerging research areas or newly introduced terminology.

Boolean Operators and Search Syntax:

  • Use Boolean operators like AND, OR, and NOT to refine searches.
  • Balancing comprehensiveness and specificity helps capture all relevant studies while avoiding an overload of irrelevant results.

For more detailed strategies and practical tips, refer to Searching the Literature: A Guide to Comprehensive Searching in the Health Sciences by the University of Toronto — an excellent resource for building and refining effective search strategies.

Screening

Once studies are retrieved, the next step is to screen these studies to determine which ones meet your inclusion and exclusion criteria. This process involves eliminating irrelevant studies that do not fit the scope of your research, to ensure that only the most relevant literature will After completing the search, the remaining studies undergo data extraction and analysis. Tools like Covidence help organize and track the screening process efficiently.

Screening Process:

The screening is conducted in two phases:

  1. Title and Abstract Screen:
    • Studies are initially reviewed based on their titles and abstracts to quickly exclude those that are clearly irrelevant.
  2. Full-Text Screen:
    • The full texts of selected studies are reviewed in detail to apply the inclusion and exclusion criteria more thoroughly.
    • At this stage, reasons for inclusion and exclusion are documented.

PRISMA Diagram:

The next step is generating the PRISMA diagram — a visual tool that tracks the entire screening process. It illustrates:

  • The total number of studies initially identified in the literature search.
  • The number of studies excluded at each screening phase.
  • The final number of studies included in the review.

The PRISMA diagram provides a clear and transparent overview of the selection process, ensuring reproducibility and clarity for other researchers.

Data Extraction

During this phase, relevant data items are extracted from the final included studies and analyzed based on your research objectives, such as identifying key trends, patterns, or findings. The data can be organized into tables or charts, and basic analysis techniques — such as frequency counts or qualitative content analysis — can be used to address the scoping review’s objectives and answer your research questions.

It is important to note that analysis in a scoping review is more descriptive than interpretive, unlike in systematic reviews. The goal is to summarize key insights from data extraction and provide a structured overview of the available evidence. Several tools, such as Covidence or even Excel, can assist with data extraction and organization.

Reporting the Results

The final step in a scoping review is reporting the results, where findings are synthesized and presented in a clear, comprehensive, and structured manner. The goal is to summarize key insights from data extraction and analysis, providing a broad overview of the available evidence to answer the review questions.

Key Components of the Reporting Phase:

  • Summary of Findings: A narrative summary outlining the main themes, trends, and patterns identified during analysis. Unlike systematic reviews, this summary does not interpret findings quantitatively.
  • Tables and Visualizations: Presenting data in tables, charts, or other visual formats to highlight key findings and facilitate comparisons across studies.
  • Discussion: A brief discussion on the implications of the findings, gaps in the literature, areas for further research, and potential policy or practice implications. This section may also acknowledge the limitations of the review process.
  • PRISMA Flow Diagram: A final PRISMA diagram visually representing the selection process, showing the number of studies identified, screened, included, and excluded at each stage.
  • Conclusion: A concise summary of the main takeaways, answering the research questions and encapsulating the current state of evidence on the topic.

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