Comprehensive and Exhaustive Searching
The goal of a systematic review is to evaluate 100% of the studies that meet the inclusion criteria. We aim for 100% of studies in order to minimize biases (both selection bias and other inherent biases).
In order to get the most complete number of studies into our review we need to conduct a comprehensive, if not exhaustive search of the literature.
- An exhaustive search is one that retrieves every single study available. We do this through a combination of searching general and subject-specific databases, grey literature, dissertations and thesis, reaching out to researchers in the field for unpublished data, and hand-searching journals.
- A comprehensive search is one that aims for completeness but is accepts that the search may not retrieve 100% of the studies.
Librarians from the Systematic Review Service can advise you on which search is right for your team.
Figure: The process of searching bibliographic databases
Source: EUnetHTA JA3WP6B2-2 Authoring Team. Process of information retrieval for systematic reviews and health technology assessments on clinical effectiveness. Methodological Guidelines. Diemen (The Netherlands): EUnetHTA; 2019. Available from https://www.eunethta.eu/
How to conduct a search
Conducting a comprehensive or exhaustive search for a systematic review or meta-analysis is a time-consuming and difficult task. It requires specialized knowledge of databases, search strategies, search syntax and controlled vocabulary, and familiarity with how to export and manage bibliographic records.
It is for this reason that most guidelines for conducting a systematic review recommend the involvement of a librarian or information specialist.
Princeton affiliates should contact the Princeton Systematic Review Service to be connected with a subject specialist for your project.
Guidelines for conducting a comprehensive search for a systematic review
- Staaks, J. (2023, March 31). Systematic Review Search Support. https://doi.org/10.17605/OSF.IO/49T8X
- Prepared by an experienced librarian at the University of Amsterdam, this document offers a thorough step-by-step explanation of designing and executing a search, including information on how to export, deduplicate, and screen bibliographic records.
- EUnetHTA JA3WP6B2-2 Authoring Team. Process of information retrieval for systematic reviews and health technology assessments on clinical effectiveness. Methodological Guidelines. Diemen (The Netherlands): EUnetHTA; 2019. Available from https://www.eunethta.eu/
Reporting the Search Strategy
The search strategy should be reported in both the protocol and the final review.
Some protocol and reporting guidelines have search reporting built in. If not you can use the PRIMSA-S: Search Reporting Extension; a checklist that will aid researchers in reporting the full search strategy in a way that is thorough and reproducible.