Development and application of an outcome-centric approach for conducting overviews of reviews

There are gaps in current guidance concerning how to conduct overviews of systematic reviews in an outcome-centric manner. Herein we summarize the methods and lessons learned from conducting 4 outcome-centric overviews to help inform the Canadian 24-Hour Movement Guidelines for Adults aged 18-64 years and Adults aged 65 years or older on the topics of resistance training, balance and functional training, sedentary behaviour, sleep duration. We defined "critical" and "important" outcomes a priori. We used AMSTAR 2 to assess review quality and sought 1 systematic review per outcome. If multiple reviews were required to address subgroups for an outcome, we calculated the corrected covered area (CCA) to quantify overlap. We report our methodology in a PRISMA table. Across the 4 overviews, authors reviewed 1110 full texts; 45 were retained (low to high quality per AMSTAR 2), representing 950 primary studies, enrolling over 5 385 500 participants. Of 46 outcomes, we identified data for 35. Nineteen outcomes required >1 review (CCA range: 0% to 71.4%). Our outcome-centric overviews addressed unique aspects of overviews, including selection and quality assessment of included reviews, and overlap. Lessons learned included consistent application of methodological principles to minimize bias and optimize reporting transparency. Novelty Overviews of reviews synthesize systematic reviews in a rigorous and transparent manner. Outcome-centric systematic reviews assess the quality of evidence for primary studies contributing to an outcome. This manuscript describes the development and application of extending the concept of outcome-centric systematic reviews to the design and conduct of outcome-centric overviews.