Statistically non-sIGNificAnt resuLts (SIGNAL): a standard framework for reporting results in evidence synthesis

Introduction The intersection of medicine, epidemiology, and biostatistics is crucial for translating complex data into actionable insights for knowledge users, including clinicians, patients, and policymakers. Systematic reviews and other forms of evidence synthesis are designed to fulfill this purpose by providing concise and unbiased summaries of the literature while also disseminating knowledge to a diverse audience. Furthermore, such analyses aim to guide future clinical research and support the development of evidence-based guidelines by various organizations. However, many of these studies tend to dichotomize results based solely on statistical significance, and there is a lack of guidance on the interpretation and reporting of statistically non-significant findings in evidence synthesis. This protocol outlines a comprehensive project aimed at addressing this critical knowledge gap by developing a standardized framework for the interpretation and reporting of such results in the literature. Methods This PhD project is structured into four interconnected Work Packages. First, we will conduct a methodological systematic review of existing guidance documents on interpreting statistically non-significant results in evidence synthesis to establish foundational knowledge. Second, building upon these initial findings, we will apply identified statistical methods to a corpus of systematic reviews and overviews of reviews, developing empirically derived thresholds and ranges for result interpretation using meaningful terminologies. Third, we will design and implement a vignette study and a Delphi exercise involving an expert advisory board and patient representatives to validate and refine the proposed framework. Fourth, the project will culminate in the publication of the developed framework based on the findings from all previous Work Packages. Ethics and dissemination We will obtain the consensus of participants in a written form prior to the start of the vignette survey and the Delphi exercise. We will disseminate the results of each Work Package of the project and the final framework through relevant English peer-reviewed journals, conferences, and workshops.