Meta-research on key metrics of preregistered scoping reviews

Scoping reviews are increasingly used for evidence synthesis, yet a comprehensive overview of benchmarks for their conduct is lacking. This study aimed to extract and analyze key metrics of preregistered scoping reviews to aid researchers in planning, resource allocation, methodological rigor, and innovation. We examined 2,038 scoping review protocol registrations on the Open Science Framework between April and August 2024, identifying 891 corresponding publications. Extracted variables included review type (e.g., rapid scoping review), information about the number of studies in the screening process, methodological practices, and funding. Using Stata, we calculated process metrics such as review duration, yield rate, and team composition. Qualitative analysis was applied to further metrics, including aims and eligibility criteria frameworks. Among the 891 publications, 91.47% were published as scoping reviews. On average, reviews involved 6.11 authors and took 80.41 weeks from registration to publication, with rapid scoping reviews completed in 55.63 weeks. Most publications (80.13%) originated from high-income countries, where funding was more common. An average of 5.19 databases were searched, identifying a mean of 6,920.66 potential inclusions, with 92.64 studies ultimately included (yield rate: 5.68%). Endnote was the most frequently employed screening tool. Language restrictions were reported in 37.60% of cases, and 75.42% did not conduct or report critical appraisal. This study provides valuable insights into common practices within scoping review processes, offering researchers a foundation to allocate resources more efficiently and enhance research quality through methodological benchmarks. It underscores the need for greater transparency and improved methodological rigor.