Umbrella reviews are studies that summarise the overarching evidence from other studies that have already summarised the evidence from individual studies evaluating the exposures and outcomes of interest. For any umbrella reviews that did not conduct their own AMSTAR evaluations, we conducted our own AMSTAR 2 evaluations. Our literature search for umbrella reviews identified 13 333 titles and abstracts ( fig 1 ); 6325 were excluded as duplicates, leaving 7008 for initial screening. We were left with 46 unique umbrella reviews that met the inclusion criteria (supplementary table 4). Additionally, we relied on the information reported in already published umbrella reviews, which relied on information reported in already published meta-analyses, which relied on the information reported in already published observational studies.

Source: The Guardian December 21, 2023 05:43 UTC