Group authorships in Cochrane had low compliance with Cochrane recommendations.

Objective: Recently, group authorships have become more common. Group authorship describes a situation where the name of a group of people is included in the byline of an article. Historically, however, group authorships have been associated with citation errors and difficulties identifying who could be regarded as an author. Cochrane is a collaboration that publishes high-quality systematic reviews and meta-analyses and transparency in authorship should be high. Group authorships in Cochrane have not previously been examined. This study aimed to describe group authorships in the Cochrane Database of Systematic Reviews (CDSR).

Methods: In total, 8396 reviews from the CDSR were screened for group authorships from inception to 31 December 2019. Data from group authorships were extracted and analyzed.

Results: A total of 41 reviews with group authorships were included. Almost half of group authorships (46%, 19/41) were published from 2015 to 2019. Median number of group members was 32 (range 6-91). Median publication time (protocol to review) of group authorships was 3.1 years. Of all group authorships, 39% met ICMJE's first authorship criterion, 41% met the second, and 12% met the third criterion. For only two studies all authors met the three authorship criteria.

Conclusion: A low prevalence of group authorships existed in Cochrane reviews. Reviews with group authorships took median three years to publish, and very few of group authorships in Cochrane complied with the ICMJE authorship criteria.