What is an Umbrella Literature Review?

An umbrella review, often called a review of reviews, is a comprehensive overview of previously published meta-analyses and systematic reviews. This method stands at the pinnacle of evidence synthesis, providing a robust approach to summarizing knowledge across multiple systematic reviews. Umbrella reviews are essential in fields such as biomedical literature, medical research, psychology, and genetics. They significantly advance the body of knowledge. The primary purpose of an umbrella review is to address the overwhelming volume of individual reviews and meta-analyses by providing a consolidated, comprehensive synthesis of findings.

The umbrella review process includes developing an umbrella review protocol, conducting a thorough literature search, and assessing the methodological quality of the included studies. This ensures that the review includes published systematic reviews and meta-analyses that are relevant and of high quality. Umbrella review authors are crucial in summarizing systematic reviews and conducting robust umbrella reviews, ultimately contributing to improved health outcomes and a better understanding of environmental factors.

When to conduct umbrella reviews?

Researchers conduct umbrella literature reviews in various contexts, primarily when there is a need for a comprehensive synthesis of evidence from multiple systematic reviews. These reviews are particularly valuable in fields like health, education, and social sciences, where decision-makers need to integrate findings from various studies to inform policies and practices. For instance, healthcare providers might use an umbrella review to develop clinical guidelines by consolidating evidence on different treatments or interventions.

Similarly, educators might conduct umbrella reviews to shape teaching strategies based on diverse educational outcomes. Umbrella reviews help identify research gaps, guide future studies, and support grant proposals by offering a high-level overview. For example, umbrella reviews can help researchers assess risk factors and environmental conditions that shape health outcomes. In other words, when practitioners and policymakers need to understand insights from a whole body of research, an umbrella review can provide great value.

In addition to informing policy and practice, umbrella literature reviews play a crucial role in academic and professional development. Graduate students and academics use these reviews to provide a comprehensive background for their theses, dissertations, and literature review articles, ensuring they build on a solid foundation of existing research. Professional organizations and NGOs also leverage umbrella reviews to make evidence-based decisions, whether in public health strategies, environmental conservation, or social welfare programs. By synthesizing evidence from numerous systematic reviews, umbrella reviews offer a thorough and efficient summary of the current state of knowledge. They facilitate informed decision-making and continuous learning across various disciplines.

What are the differences between umbrella reviews and other reviews?

Umbrella reviews differ from other types of literature reviews in several key ways. While systematic reviews and meta-analyses focus on synthesizing data from primary studies to address specific research questions, umbrella reviews go a step further by summarizing the results of multiple systematic reviews and meta-analyses. This approach provides a higher level of evidence synthesis, allowing for a broader understanding of the research landscape on a given topic (Snyder, 2019; Kelley, 2011).

Unlike individual systematic reviews that may concentrate on specific interventions or outcomes, umbrella reviews offer a more comprehensive perspective. They integrate findings from various systematic reviews published on the same topic, which helps identify consistent patterns, highlight differences, and provide a more nuanced understanding of the evidence. For example, an umbrella review might combine data from several systematic reviews on different interventions for the same health condition, thereby offering a holistic view of treatment options and outcomes.

Umbrella reviews also involve a rigorous methodological approach. They typically include a well-defined protocol that outlines the inclusion and exclusion criteria, search strategy, and methods for data extraction and analysis (Baumeister & Leary, 1997). This ensures that the review process is transparent and reproducible. Umbrella reviews often use critical appraisal tools, such as the PRISMA statement and the JBI critical appraisal tool, to assess the quality of the included reviews.

Another key difference is that umbrella reviews are particularly useful in fields with rapidly evolving research landscapes, such as biomedical literature, where the volume of systematic reviews and meta-analyses can become overwhelming. By providing a consolidated synthesis of evidence, umbrella reviews help researchers and decision-makers stay abreast of the latest findings and make informed decisions based on the most comprehensive and up-to-date evidence available (Mohamed-Shaffril, Samsuddin, & Abu Samah, 2021).

While systematic reviews and meta-analyses are invaluable for synthesizing primary research data, umbrella reviews offer a higher level of evidence synthesis by integrating findings from multiple systematic reviews. This comprehensive approach provides a more complete and nuanced understanding of the evidence, making umbrella reviews an essential tool for evidence-based practice and policy-making.

Conducting an umbrella review involves a systematic process developed and refined by leading researchers such as Baumeister and Leary (1997), and Higgins et al. (2019). Here are the steps to conduct an umbrella review:

1. Define the scope and objectives: Outline the research questions and objectives. Specify the topic or intervention the umbrella review will cover. This step sets the direction of the review and ensures the scope is manageable.

2. Develop a protocol: Establish a detailed protocol with inclusion and exclusion criteria, search strategy, and methods for data extraction and analysis. The Joanna Briggs Institute (JBI) and Cochrane Handbook provide guidelines and tools for robust protocols (Higgins et al., 2019). The protocol ensures the included studies are relevant and of high quality.

3. Literature search: Conduct a comprehensive search of databases to find previously published systematic reviews and meta-analyses. Use search strategies to capture all relevant reviews, including open access articles and international journals. This step ensures a broad range of evidence is captured.

4. Screen and select studies: Screen studies for relevance based on predefined criteria and select systematic reviews and meta-analyses that meet the inclusion criteria. Carefully evaluate each study to ensure it fits within the review's scope.

5. Data extraction: Extract data using a standardized form, including study characteristics, methodologies, and key findings. Ensure data is properly cited and documented. This step is critical for accurate synthesis of the evidence.

6. Critical appraisal: Assess the methodological quality of the included reviews using tools like the PRISMA statement and the JBI critical appraisal tool.

7. Synthesize findings: Summarize and synthesize the data from the selected reviews. Present results in a tabular format to highlight key findings, trends, and gaps. Integrate findings from multiple reviews for a comprehensive overview (Baumeister & Leary, 1997).

8. Report and interpret results: Write a comprehensive report including the background, methodology, results, discussion, and conclusions. Interpret the findings in the context of existing evidence and provide recommendations for practice and future research. Present findings clearly to make them accessible to a wide audience (Coughlan et al., 2007).

Conclusion

Umbrella literature reviews are invaluable methods in the realm of evidence synthesis. By compiling and analyzing data from multiple systematic reviews and meta-analyses, umbrella reviews provide a high-level overview of the evidence on a particular topic. This method helps you summarize the vast amount of information available, identify research gaps, inform clinical practice, and guide policy decisions. As the volume of published systematic reviews continues to grow, the importance of umbrella reviews in delivering comprehensive and coherent evidence-based insights becomes increasingly evident. The umbrella review process, which includes developing a detailed umbrella review protocol and summarizing systematic reviews, ensures high-quality evidence synthesis.

References

Baumeister, R. F., & Leary, M. R. (1997). Writing narrative literature reviews. Review of General Psychology, 1(3), 311-320.

Higgins, J. P., Thomas, J., Chandler, J., Cumpston, M., Li, T., Page, M. J., & Welch, V. A. (Eds.). (2019). Cochrane Handbook for Systematic Reviews of Interventions. John Wiley & Sons.