Half of Cochrane reviews were published more than 2 years after the protocol.

Objectives: The objective of the study is to examine the time from publication of the protocol for a Cochrane review to publication of the Cochrane review for the entire Cochrane Database of Systematic Reviews (CDSR).

Study Design And Settings: Cochrane reviews from the CDSR published between 1995 and 2019 were assessed. Characteristics of the reviews were extracted, and time from publication of protocol to publication of review was calculated. These times were grouped for relevant characteristics and visualized through charts and tables to illustrate trends.

Results: Of the total 8,201 reviews in the CDSR, 6,764 were included. The median publication time was 2 years (range 0 days to 21.7 years). Reviews that were published more than 5 years after the protocol made up 11% of all included reviews, whereas 19% of reviews were published within a year. The median publication time for the individual Cochrane Review Groups ranged from 15 to 39 months.

Conclusion: Half of Cochrane reviews were published later than Cochrane's aim of 2 years. Furthermore, the Cochrane Review Groups' median times from publication of protocol to publication of review varied widely.