Background: Bibliographic databases and trial registers must be searched in Cochrane reviews. CENTRAL, MEDLINE, and Embase are mandatory to search, while ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform portal are considered the most important to search. According to Technical Supplement 4, searching appropriate national and regional databases is desirable. However, it may be challenging to acquire and assess non-English records. We encountered this while conducting a Cochrane review and reached out to Cochrane China for assistance.
Objectives: To report the effects and the experience of collaboration across languages and continents in a Cochrane review.
Methods: The search methods were published in the protocol. This included forward citation searches, which led to the identification of Chinese literature on the subject. The first author spoke and could read Chinese but was not a native speaker. When Chinese evidence started to gather, we reached out to Cochrane China. They immediately provided us with a capable native Chinese coauthor with good skills in written English, who assisted in review conduct and fulfilled all authorship criteria.
Results: The search in the standard databases and trial registers resulted in five of the included trials (355 participants). The search through other sources (mainly forward citation search) almost tripled the amount of evidence identified, resulting in 10 additional trials (658 participants) and 2 trials awaiting classification (194 participants). To facilitate the review conduct, assistance was needed from a native Chinese author. The selection of studies, data extraction and bias assessment were done independently. Several online meetings were held to confirm decisions. To facilitate these, both sides needed assistance from a native Chinese speaker and a person from Cochrane China more familiar with spoken English, respectively. Further reference search, identification of reports and contact to study authors were also conducted in collaboration with the native Chinese coauthor.
Conclusions: Evidence collected outside the search in databases and trial registers can considerably increase the amount of evidence. However, to access and evaluate these data, collaboration across Cochrane centres may be needed. This can result in a fruitful collaboration and the involvement of native-speaking coauthors.