Trial Registries for Systematic Reviews

Trial registries are publicly accessible databases that list clinical trials, including ongoing, completed, and unpublished studies. Searching them helps minimize publication bias and identify grey literature.

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• ClinicalTrials.gov

https://clinicaltrials.gov Largest global registry maintained by the U.S. National Library of Medicine. Covers trials worldwide.

• WHO International Clinical Trials Registry Platform (ICTRP)

https://trialsearch.who.int Aggregates multiple national and regional registries into a single search portal.

• European Union Clinical Trials Register (EUCTR)

https://www.clinicaltrialsregister.eu Contains interventional clinical trials conducted in the European Union and European Economic Area.

• ISRCTN Registry

https://www.isrctn.com A primary clinical trial registry recognized by WHO and ICMJE.

• Chinese Clinical Trial Registry (ChiCTR)

http://www.chictr.org.cn Primary registry for trials conducted in China.

• Clinical Research Information Service (CRiS)

https://cris.nih.go.kr South Korean clinical trials registry.

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• Use broad keywords and synonyms related to your PICO question.
• Filter by study status (e.g., recruiting, completed).
• Export results where possible for screening.
• Document search date, strategy, and results as part of your review.

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• Identify unpublished or ongoing trials to reduce publication bias.
• Access detailed protocols, sample sizes, and outcomes.
• Check for discrepancies between registered protocols and published reports.