Umbrella reviews: what they are and why we need them

Excerpt

Evidence in clinical research and public health is hierarchical. From animal studies to observational epidemiology, randomized control trials and their synthesis, there is a pipeline of different study designs providing different nature and quality of information. Systematic reviews and meta-analyses stand on top of this hierarchy most of the times and are key components of evidence-based medicine [1]. Their production and publication has increased exponentially in the last decade across almost all disciplines with approximately 20,000 records labeled as meta-analysis in 2018 compared to 3300 in 2008. One would expect that this growth would reflect the increase in the number of primary observational and experimental studies but this is not true because all Pubmed-indexed items increased by 153% from 1991 to 2014 [2]. …