The life and death of living systematic reviews: a methodological survey

Objectives: The objectives of this study are to describe the characteristics of living systematic reviews (LSRs) and to understand their life cycles.Study Design and Setting: We conducted a comprehensive search up to April 2021 then selected articles and abstracted data in dupli-cate and independently. We undertook descriptive analyses and calculated delay in version update and delay since the last published version.Results: We included 76 eligible LSRs with a total of 279 eligible versions. The majority of LSRs was from the clinical field (70%), was COVID-19 related (63%), and had a funding source specified (62%). The median number of versions per LSR was 2 (interquartile range (IQR) 1-4; range 1-19). The median and IQR for the ratio of the actual period of update to the planned period of update was 1.12 (0.81; 1.71). Out of all reviews with a 'planned period of update' and at least one update (N 5 19), eight LSRs (42%) had a period since last published version greater than 3 times the planned period of update. No LSR included a 'retirement notice' in their latest pub-lished version.Conclusion: While most LSR complied with the planned period of producing updates, a substantive proportion lagged since their last update.(c) 2023 Elsevier Inc. All rights reserved.