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Highlights: This is the first empirical study to replicate Jadad algorithm assessments to evaluate discordance across systematic reviews. In 62% (13/21) of cases, we were unable to replicate the Jadad algorithm assessment and ultimately chose a different systematic review than the authors. When assessing systematic reviews using the Jadad algorithm, some steps of the Jadad algorithm were vague in description, making it difficult to operationalise, interpret, and use. The Jadad algorithm has several limitations as it does not account for the last literature search of the systematic review and publication recency of included trials. To assess discordance in the absence of an algorithm, we recommend decision makers consider relevance (objectives that most closely resemble their clinical question), recency (dates of search), comprehensiveness (most trials), and risk of bias (lowest risk of bias SR) when choosing one systematic review across multiple.

Introduction An increasing growth of systematic reviews (SRs) presents notable challenges for decision-makers seeking to answer clinical questions. In 1997, an algorithm was created by Jadad to assess discordance in results across SRs on the same question. Our study aims to (1) replicate assessments done in a sample of studies using the Jadad algorithm to determine if the same SR would have been chosen, (2) evaluate the Jadad algorithm in terms of utility, efficiency and comprehensiveness, and (3) describe how authors address discordance in results across multiple SRs.Methods and analysis We will use a database of 1218 overviews (2000–2020) created from a bibliometric study as the basis of our search for studies assessing discordance (called discordant reviews). This bibliometric study searched MEDLINE (Ovid), Epistemonikos and Cochrane Database of Systematic Reviews for overviews. We will include any study using Jadad (1997) or another method to assess discordance. The first 30 studies screened at the full-text stage by two independent reviewers will be included. We will replicate the authors’ Jadad assessments. We will compare our outcomes qualitatively and evaluate the differences between our Jadad assessment of discordance and the authors’ assessment.Ethics and dissemination No ethics approval was required as no human subjects were involved. In addition to publishing in an open-access journal, we will disseminate evidence summaries through formal and informal conferences, academic websites, and across social media platforms. This is the first study to comprehensively evaluate and replicate Jadad algorithm assessments of discordance across multiple SRs.