title: Data harmonization and federated analysis of population-based studies: the BioSHaRE project.
abstract: BACKGROUND
  Individual-level data pooling of large population-based studies across research centres in international research projects faces many hurdles. The BioSHaRE (Biobank Standardisation and Harmonisation for Research Excellence in the European Union) project aims to address these issues by building a collaborative group of investigators and developing tools for data harmonization, database integration and federated data analyses.
  
  
  METHODS
  Eight population-based studies in six European countries were recruited to participate in the BioSHaRE project. Through workshops, teleconferences and electronic communications, participating investigators identified a set of 96 variables targeted for harmonization to answer research questions of interest. Using each study's questionnaires, standard operating procedures, and data dictionaries, harmonization potential was assessed. Whenever harmonization was deemed possible, processing algorithms were developed and implemented in an open-source software infrastructure to transform study-specific data into the target (i.e. harmonized) format. Harmonized datasets located on server in each research centres across Europe were interconnected through a federated database system to perform statistical analysis.
  
  
  RESULTS
  Retrospective harmonization led to the generation of common format variables for 73% of matches considered (96 targeted variables across 8 studies). Authenticated investigators can now perform complex statistical analyses of harmonized datasets stored on distributed servers without actually sharing individual-level data using the DataSHIELD method.
  
  
  CONCLUSIONS
  New Internet-based networking technologies and database management systems are providing the means to support collaborative, multi-center research in an efficient and secure manner. The results from this pilot project show that, given a strong collaborative relationship between participating studies, it is possible to seamlessly co-analyse internationally harmonized research databases while allowing each study to retain full control over individual-level data. We encourage additional collaborative research networks in epidemiology, public health, and the social sciences to make use of the open source tools presented herein.
authors.affiliation: Research Institute of the McGill University Health Centre, 2155 Guy, office 458, Montreal, Quebec H3H 2R9, Canada.|Public Population Project in Genomics and Society, Montreal, Canada.
authors.forename: Dany
authors.initials: D
authors.lastname: Doiron
authors.affiliation: D2K Research Group, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Burton
authors.affiliation: Research Institute of the McGill University Health Centre, 2155 Guy, office 458, Montreal, Quebec H3H 2R9, Canada.
authors.forename: Yannick
authors.initials: Y
authors.lastname: Marcon
authors.affiliation: D2K Research Group, School of Social and Community Medicine, University of Bristol, Bristol, UK.
authors.forename: Amadou
authors.initials: A
authors.lastname: Gaye
authors.affiliation: Department of Endocrinology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Bruce H R
authors.initials: BHR
authors.lastname: Wolffenbuttel
authors.affiliation: Department of Chronic Disease Prevention, Public Health Genomics Unit, National Institute for Health and Welfare, Helsinki, Finland.|Institute for Molecular Medicine, University of Helsinki, Helsinki, Finland.
authors.forename: Markus
authors.initials: M
authors.lastname: Perola
authors.affiliation: Department of Epidemiology, University Medical Center Groningen, Groningen, The Netherlands.
authors.forename: Ronald P
authors.initials: RP
authors.lastname: Stolk
authors.affiliation: European Academy of Bolzano/Bozen (EURAC), Center for Biomedicine, Bolzano, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Foco
authors.affiliation: Respiratory Epidemiology, Occupational Medicine and Public Health, National Heart and Lung Institute, Imperial College, London, UK.
authors.forename: Cosetta
authors.initials: C
authors.lastname: Minelli
authors.affiliation: Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany.
authors.forename: Melanie
authors.initials: M
authors.lastname: Waldenberger
authors.affiliation: Helmholtz Zentrum München - German Research Center for Environmental Health, Neuherberg, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Holle
authors.affiliation: Department of Public Health and General Practice, HUNT Research Center, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: Kirsti
authors.initials: K
authors.lastname: Kvaløy
authors.affiliation: Department of Cardiology and Epidemiology, University Medical Centre Groningen, Groningen, The Netherlands.
authors.forename: Hans L
authors.initials: HL
authors.lastname: Hillege
authors.affiliation: Public Population Project in Genomics and Society, Montreal, Canada.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Tassé
authors.affiliation: Ontario Institute for Cancer Research, MaRS Centre, Toronto, Canada.
authors.forename: Vincent
authors.initials: V
authors.lastname: Ferretti
authors.affiliation: Research Institute of the McGill University Health Centre, 2155 Guy, office 458, Montreal, Quebec H3H 2R9, Canada.
authors.forename: Isabel
authors.initials: I
authors.lastname: Fortier