Evaluating Cochrane's centralised search and screening processes: a retrospective analysis of the Cochrane Central Register of Controlled Trial's (CENTRAL) coverage


Oral session: Searching and information retrieval (3)


Thursday 24 October 2019 - 11:00 to 12:30


All authors in correct order:

Noel-Storr A1, Featherstone R2, Glanville J3, Wisniewski S1, Dooley G4, Thomas J5, Foxlee R2
1 Cochrane Dementia and Cognitive Improvement Group, UK
2 Cochrane, UK
3 York Health Economics Consortium, UK
4 Metaxis, UK
5 University College London, UK
Presenting author and contact person

Presenting author:

Anna Noel-Storr

Contact person:

Abstract text
Background: Cochrane populates its Centralised Register of Controlled Trials (CENTRAL) through centralised searches from many sources, including data feeds from PubMed and Embase. Over the last few years, we have increased the number of sources feeding into CENTRAL and improved the efficiency of our processes through the use of application programming interfaces (APIs), machine learning (RCT classifier) and crowdsourcing (manual screening of records by Cochrane Crowd).

Objectives: our objectives were to:
- assess the effectiveness of Cochrane’s centralised search and screening processes to identify eligible trials for inclusion in systematic reviews;
- understand why relevant trials may have been missed by our processes;
- inform enhancements to improve CENTRAL's coverage of eligible trials.

Methods: we identified all RCTs (whether they were published journal articles or trial registration records) with a publication date between 1 January 2017 and 31 December 2018 that had been included as an included study in a Cochrane Review. We then ran an audit trail on each record using the record’s bibliographic database accession number or trial registration ID number, to determine if the study had been identified by our centralised search process and added to CENTRAL. We reviewed the search and screening processes to understand why any RCTs included in those reviews, were not captured by the centralised processes.

Results: this analysis is currently ongoing. At the Colloquium we will present the results. This will include:
- the proportion and number of included studies not captured by the centralised search process;
- the proportion and number of included studies not captured by the centralised screening process;
- an in-depth analysis on studies not captured by either the search or screening process
- recommendations on how to improve the centralised searching and screening processes if necessary.

Conclusions: these new processes have significantly enriched CENTRAL. This makes it an essential resource for researchers around the world wanting to identify the available RCT evidence on a healthcare topic. This analysis will help to identify ways we can improve our processes for harvesting RCT records for CENTRAL.

Patient or healthcare consumer involvement: Cochrane Crowd contributors have played a critical role in helping to identify RCTs for CENTRAL. This analysis will demonstrate that the Crowd have potentially helped to identify hundreds of studies included in Cochrane Reviews of interventions, demonstrating the value of wider consumer involvement in the production of health evidence.