Introduction: The Cochrane Handbook recommends searching clinical trials registries for systematic reviews of interventions, including specifically clinicaltrials.gov (CTG). Trial records from CTG are also indexed in the World Health Organization International Clinical Trials Registry Platform (ICTRP), Cochrane Central and, as of October 2025, in the Embase database.
Current guidance recommends searching CTG through the native platform as well as the ICTRP platform, due to differences in search functionality and indexing of the records. With Embase now including CTG records, we sought to determine whether all relevant CTG records can be retrieved from searching Embase.
Methods: We conducted an exploratory information retrieval study on the recall of relevant CTG records within an Embase search. We used search strategies and included studies from previously published Cochrane reviews of interventions, published in 2025. Cochrane reviews that searched Embase, CTG, and ICTRP were eligible for inclusion. We replicated their searches in each source, and exported the records. We then checked each retrieval set against all CTG trial records/numbers mentioned in the ‘references to studies included in this review’ section of each review, and calculated recall for each source. For missed CTG records, we confirmed whether it was present in the platform. And in the case of Embase, we explored why some were missed from the search.
Results: Results TBA
Discussion/Conclusion: The findings of this study provides initial evidence on whether CTG records can be reasonably retrieved through a search of Embase, and whether the existing evidence stating that both CTG and ICTRP should be searched separately is still true.