title: The geometric increase in meta-analyses from China in the genomic era.
abstract: Meta-analyses are increasingly popular. It is unknown whether this popularity is driven by specific countries and specific meta-analyses types. PubMed was used to identify meta-analyses since 1995 (last update 9/1/2012) and catalogue their types and country of origin. We focused more on meta-analyses from China (the current top producer of meta-analyses) versus the USA (top producer until recently). The annual number of meta-analyses from China increased 40-fold between 2003 and 2011 versus 2.4-fold for the USA. The growth of Chinese meta-analyses was driven by genetics (110-fold increase in 2011 versus 2003). The HuGE Navigator identified 612 meta-analyses of genetic association studies published in 2012 from China versus only 109 from the USA. We compared in-depth 50 genetic association meta-analyses from China versus 50 from USA in 2012. Meta-analyses from China almost always used only literature-based data (92%), and focused on one or two genes (94%) and variants (78%) identified with candidate gene approaches (88%), while many USA meta-analyses used genome-wide approaches and raw data. Both groups usually concluded favorably for the presence of genetic associations (80% versus 74%), but nominal significance (P<0.05) typically sufficed in the China group. Meta-analyses from China typically neglected genome-wide data, and often included candidate gene studies published in Chinese-language journals. Overall, there is an impressive rise of meta-analyses from China, particularly on genetic associations. Since most claimed candidate gene associations are likely false-positives, there is an urgent global need to incorporate genome-wide data and state-of-the art statistical inferences to avoid a flood of false-positive genetic meta-analyses.
authors.affiliation: Epidemiology and Genomics Research Program, Division of Cancer Control and Population Sciences, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America. jioannid@stanford.edu
authors.forename: John P A
authors.initials: JP
authors.lastname: Ioannidis
authors.forename: Christine Q
authors.initials: CQ
authors.lastname: Chang
authors.forename: Tram Kim
authors.initials: TK
authors.lastname: Lam
authors.forename: Sheri D
authors.initials: SD
authors.lastname: Schully
authors.forename: Muin J
authors.initials: MJ
authors.lastname: Khoury
mesh_terms: D015706:Bibliometrics; D002681:China; D056726:Genetic Association Studies / Q000266:history / Q000706:statistics & numerical data*; D049674:History, 21st Century; D015201:Meta-Analysis as Topic; D039781:PubMed / Q000706:statistics & numerical data*