Abstract
BACKGROUND: A living systematic review (LSR) is an emerging review type that makes use of continual updating. In the COVID-19 pandemic, we were confronted with a shifting epidemiological landscape, clinical uncertainties and evolving evidence. These unexpected challenges compelled us to amend standard LSR methodology. OBJECTIVE AND OUTLINE: Our primary objective is to discuss some challenges faced when conducting LSRs in the context of the COVID-19 pandemic, and to provide methodological guidance for others doing similar work. Based on our experience and lessons learned from two Cochrane LSRs and challenges identified in several non-Cochrane LSRs, we highlight methodological considerations, particularly with regards to the study design, interventions and comparators, changes in outcome measure, and the search strategy. We discuss when to update, or rather when not to update the review, and the importance of transparency when reporting changes. LESSONS LEARNED AND CONCLUSION: We learned that a LSR is a very suitable review type for the pandemic context, even in the face of new methodological and clinical challenges. Our experience showed that the decision for updating a LSR depends not only on the evolving disease or emerging evidence, but also on the individual review question and the review teams' resources.