Construct and Run Search Strategies

Developing a thorough and reproducible search is one of the most important parts in conducting reviews. For more information on how to use PICO (or similar) frameworks and translate your research question to a search string, visit the Literature Searching guide. 

A well-crafted search strategy ensures that all relevant studies are identified, minimizing bias and enhancing the reliability of your review’s findings. For more information on how a general research search strategy differs from a systematic search strategy, visit the Systematic Searching tab on the left.

Below are the key steps to effectively construct and execute your search strategies:

Search Core Databases

• Begin by searching at least three core databases that cover your topic area comprehensively. Examples include PubMed, Embase, CINAHL, and Scopus. These databases provide access to a broad range of peer-reviewed studies, including clinical trials and systematic reviews.  You will need to document not only the search strategies for each database but also the dates and limiters in your supplemental documents.

Collaborate with a Librarian

• Reach out to Lewis librarians to help conduct search strategies. Librarians can assist with selecting appropriate databases, developing comprehensive search terms, and refining your search strategy so that relevant studies are not missed. Collaboration also helps guarantee reproducibility of your search, which is essential to the systematic review process.

Document Your Search Using PRISMA-S

• Ensure you document your searches following the PRISMA-S (Preferred Reporting Items for Systematic Reviews and Meta-Analyses search extension) checklist; this documentation will contain items such as:

  • The databases searched

  • The date of the search

  • The keywords and Boolean operators used

  • Any filters or limits applied

  • Any adjustments made during the search process

• This documentation ensures transparency and allows others to replicate your search strategy if needed.

Search Grey Literature

Grey literature refers to research and publications that are not formally published in academic journals or widely indexed in traditional databases. This can include a range of materials such as conference proceedings, clinical trial registries, dissertations, government reports, and publications from professional organizations or think tanks. Searching grey literature is an essential step in conducting a thorough systematic review, as it helps minimize publication bias by identifying studies that may have been excluded from traditional databases.

How to Search Grey Literature

• Clinical Trial Registries: Search registries like ClinicalTrials.gov, EU Clinical Trials Register, and WHO International Clinical Trials Registry Platform (ICTRP) to find unpublished clinical trial data.

• Conference Proceedings: Many important studies are first presented at conferences before they are published. Searching databases like ProceedingsFirst or PapersFirst can help fill in the gaps.

• Dissertations and Theses: Explore repositories like UNTHSC Dissertations & Theses or WorldCat Dissertations & Theses for unpublished graduate theses and dissertations.

• Government and NGO Reports: Government agencies, NGOs, and research institutes often publish reports that are not indexed in traditional databases. Examples include the National Institutes of Health (NIH) and World Health Organization (WHO).

• Professional Association Websites: Many professional organizations publish research reports, guidelines, or policy documents on their websites that may not be found in mainstream journals.Look for regional, national, and international professional organizations.

• Preprint Repositories: Sites like arXiv, bioRxiv, and SSRN host early-stage research and studies awaiting peer review that can provide valuable insights. Use the Directory of Open Access Preprint Repositories to access the resources listed and find more.

Tools for Searching Grey Literature

• OpenGrey: A multidisciplinary repository for grey literature in Europe, offering access to reports, conference papers, and other unpublished works.

• GreyNet International: A portal dedicated to grey literature research, offering access to a wide range of non-commercial publications.

• Google Scholar: Although it’s mostly used for academic papers, Google Scholar can also help in finding grey literature, particularly reports or conference papers not traditionally indexed.

Direct Outreach

Consider contacting researchers directly to inquire about unpublished data or studies not found in any database. This could involve reaching out to researchers in the field via email or professional networks like ResearchGate or LinkedIn to request data from ongoing or completed studies that are not yet published.

Searching actively within the grey literature thus guarantees the systematic review covers the entire spectrum of the available evidence, fostering a more complete and balanced view of the topic.

Export and Manage Citations

Efficient citation management is a key part of the systematic review process, ensuring that your references are organized and easy to access as you conduct your review. By using reference management tools, you can streamline this process, reduce errors, and ensure that all studies are accurately included. Here are the key steps to manage and organize your citations:

Use a Reference Manager

• Utilize reference management tools such as EndNote (provided by Lewis Library) or Zotero (an open source program) to organize and manage your citations. These tools allow you to store and categorize references, making it easier to find and manage studies throughout the review process. For EndNote users, we have a detailed guide available to help you get started here.

• Covidence is also a powerful tool for managing citations during systematic reviews, helping with screening, data extraction, and collaboration among team members. Submit your request to join the UNTHSC Covidence account to AskALibrarian@unthsc.edu.

De-duplicate References

As you search through various databases, you may encounter duplicate references. It is important to de-duplicate these references so that they are correctly accounted for and so that no study is counted twice in your review. Most reference management tools, like EndNote and Covidence, offer de-duplication features that automatically detect and remove duplicate entries from your citation list.

Track Inclusion and Exclusion Decisions

Preserve the transparency of the review by charting your decisions to include or exclude using the PRISMA Flow Diagram. The diagram tracks the studies at every stage of the review, from inception of the search to final inclusion, providing an open and accurate account of your selection process.

By utilizing these tools and strategies, you can efficiently manage your citations, reduce errors, and maintain the rigor and transparency required in a systematic review.