Background: Although the production of living systematic reviews (LSRs) follows the core principles of systematic review methodology, their key distinguishing feature is the continual incorporation of relevant new evidence as it emerges.
Objectives: As part of an effort to develop an extension of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 statement for LSRs, we discuss conceptual issues relevant to the reporting of LSRs and highlight a few challenges.
Methods: The issues discussed are based on a scoping review of the literature and discussions amongst authors. We also build on previous work related to updating systematic reviews.
Results: We first describe aspects of the LSR production process relevant to reporting. The production cycles differ by whether the literature surveillance identifies new evidence and whether newly identified evidence is judged to be consequential. This impacts the timing, content, and format of LSR versions. Second, we discuss four types of information that are specific to the reporting of LSRs: justification for adopting the living mode, LSR specific methods, changes between LSR versions, and LSR updating status. We also discuss the challenge of conveying changes between versions to the reader. Third, we describe two commonly used reporting formats of LSRs: full and partial reports. Although partial reports are easier to produce and publish, they lead to the scattering of information across different versions. Full reports ensure the completeness of reporting. We discuss the implications for the extension of the PRISMA 2020 statement for LSRs.
Conclusions: The extension of the PRISMA 2020 statement for LSRs would need to account for LSR specific information to report. A dynamic publication platform that decreases the burden of production and publication of full reports would facilitate complete and timely reporting of LSRs. Patient, public, and/or healthcare consumer involvement: There was no involvement. Improving the reporting of LSRs is essential for providing stakeholders with synthesized evidence in a timely manner.

Production processes of standard SR, LSR.png
Scenarios for update cycles of LSR.png