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Overview of retrospective data harmonisation in the MINDMAP project: process and results
  1. Tina W Wey1,
  2. Dany Doiron1,
  3. Rita Wissa1,
  4. Guillaume Fabre1,
  5. Irina Motoc2,
  6. J Mark Noordzij3,
  7. Milagros Ruiz4,
  8. Erik Timmermans2,
  9. Frank J van Lenthe3,5,
  10. Martin Bobak4,
  11. Basile Chaix6,
  12. Steinar Krokstad7,8,
  13. Parminder Raina9,10,11,
  14. Erik Reidar Sund7,8,12,
  15. Marielle A Beenackers3,
  16. Isabel Fortier1
  1. 1 Maelstrom Research, Research Institute of the McGill University Health Centre, Montreal, Canada
  2. 2 Department of Epidemiology and Biostatistics, Amsterdam UMC, VU University Medical Center, Amsterdam Public Health Research Institute, Amsterdam, Netherlands
  3. 3 Department of Public Health, Erasmus University Medical Center, Rotterdam, Netherlands
  4. 4 Research Department of Epidemiology and Public Health, University College London, London, UK
  5. 5 Department of Human Geography and Spatial Planning, Utrecht University, Utrecht, Netherlands
  6. 6 Sorbonne Université, INSERM, Institut Pierre Louis d’Épidémiologie et de Santé Publique, Nemesis research team, Paris, France
  7. 7 HUNT Research Centre, Department of Public Health and Nursing, Norwegian University of Science and Technology, Levanger, Norway
  8. 8 Levanger Hospital, Nord-Trøndelag Hospital Trust, Levanger, Norway
  9. 9 Department of Health Research Methods, Evidence, and Impact, McMaster University, Hamilton, Canada
  10. 10 McMaster Institute for Research on Aging, McMaster University, Hamilton, Canada
  11. 11 Labarge Centre for Mobility in Aging, McMaster University, Hamilton, Canada
  12. 12 Faculty of Nursing and Health Sciences, Nord Universitet—Levanger Campus, Levanger, Norway
  1. Correspondence to Tina W Wey, Maelstrom Research, Research Institute of the McGill University Health Centre, 1650 Cedar Ave, Montreal, QC H3G 1A4, Canada; twey{at}


Background The MINDMAP project implemented a multinational data infrastructure to investigate the direct and interactive effects of urban environments and individual determinants of mental well-being and cognitive function in ageing populations. Using a rigorous process involving multiple teams of experts, longitudinal data from six cohort studies were harmonised to serve MINDMAP objectives. This article documents the retrospective data harmonisation process achieved based on the Maelstrom Research approach and provides a descriptive analysis of the harmonised data generated.

Methods A list of core variables (the DataSchema) to be generated across cohorts was first defined, and the potential for cohort-specific data sets to generate the DataSchema variables was assessed. Where relevant, algorithms were developed to process cohort-specific data into DataSchema format, and information to be provided to data users was documented. Procedures and harmonisation decisions were thoroughly documented.

Results The MINDMAP DataSchema (v2.0, April 2020) comprised a total of 2841 variables (993 on individual determinants and outcomes, 1848 on environmental exposures) distributed across up to seven data collection events. The harmonised data set included 220 621 participants from six cohorts (10 subpopulations). Harmonisation potential, participant distributions and missing values varied across data sets and variable domains.

Conclusion The MINDMAP project implemented a collaborative and transparent process to generate a rich integrated data set for research in ageing, mental well-being and the urban environment. The harmonised data set supports a range of research activities and will continue to be updated to serve ongoing and future MINDMAP research needs.

  • Cohort studies
  • epidemiology
  • longitudinal studies
  • methodology

This is an open access article distributed in accordance with the Creative Commons Attribution 4.0 Unported (CC BY 4.0) license, which permits others to copy, redistribute, remix, transform and build upon this work for any purpose, provided the original work is properly cited, a link to the licence is given, and indication of whether changes were made. See:

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  • Twitter Tina Wey @tina_wey.

  • Acknowledgements The authors would like to thank Asli Gurer and Aliou Sarr for their contribution to data harmonisation work at Maelstrom Research; Dr Mauricio Avendano Pabon for general feedback on manuscript content; Dr Martijn Huisman for his assistance with data procurement; and Dr Ivet Bayes Marin, Professor Michael Dewey, Dr Lauren Griffith, Professor Scott Hofer, Dr Graciela Muniz Terrera and Dr Albert Sanchez Niubo for their invaluable input and expertise on the harmonisation of mental health and cognition data. This research was made possible using the data/biospecimens collected by the Canadian Longitudinal Study on Aging (CLSA). The CLSA is led by Drs Parminder Raina, Christina Wolfson and Susan Kirkland. We also thank two anonymous reviewers for constructive feedback on an earlier version of the manuscript.

  • Contributors IF conceptualised the manuscript. TWW drafted and developed the manuscript with IF. DD, RW and GF contributed to manuscript development and content. MAB, DD and RW coordinate the MINDMAP harmonisation infrastructure and database. MAB, RW, IM, JMN, MR and ET were the leads on harmonisation subject domains. Harmonisation leads and GF, AG and AS performed technical harmonisation work. IF coordinates the development of Maelstrom Research harmonisation guidelines and tools that were applied. FJvL and MA coordinate the MINDMAP project. FJvL, MB, BC, SK, PR, ERS and MH coordinate the included cohort studies and were involved in study design and data collection. MAB, IM, JMN, MR and ET were also members of cohort study teams. MAB, IM, JMN, MR, ET, FJvL, BC, PR and ERS provided critical feedback on the manuscript. All authors reviewed and approved the manuscript.

  • Funding MINDMAP is supported by the European Commission HORIZON 2020 Programme under grant agreement #667661. The article does not reflect the Commission’s views and in no way anticipates the Commission’s future policy in this area. MAB was funded by a Netherlands Organization for Scientific Research (NWO) VENI grant on ‘DenCityHealth: How to keep growing urban populations healthy?’ (grant number 09150161810158). Funding for the Canadian Longitudinal Study on Aging (CLSA) is provided by the Government of Canada through the Canadian Institutes of Health Research (CIHR) under grant reference: LSA 94473 and the Canada Foundation for Innovation. The opinions expressed in this manuscript are the authors’ own and do not reflect the views of the Canadian Longitudinal Study on Aging. PR holds the Raymond and Margaret Labarge Chair in Optimal Aging and Knowledge Application for Optimal Aging, is the Director of the McMaster Institute for Research on Aging and the Labarge Centre for Mobility in Aging, and holds a Tier 1 Canada Research Chair in Geroscience.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval Secondary use of cohort data for the MINDMAP harmonisation project received a declaration of no objection from the Medical Ethical Committee of Erasmus University Medical Centre. Data transfer agreements were established between all partners providing or analysing harmonised data. Cohort studies originally received informed consent of participants and ethical approval from their respective institutions. CLSA received ethical approval from the Hamilton Integrated Research Ethics Board. This research has been conducted using the CLSA data set, Baseline Comprehensive Dataset version 4.0, under Application Number 171013. GLOBE received a declaration of no objection from the Medical Ethical Committee of Erasmus MC. HAPIEE received ethical approval from the Joint UCL/UCLH Committees on the Ethics of Human Research. Ethical approval was also received from all local institutes: the Jagiellonian University’s Committee on the Ethics of Clinical Research, the Kaunas Regional Biomedical Research Ethical Committee and the Institution Ethical Commission of the Czech Republic—National Institute of Public Health. HUNT received ethical approval from the Regional Committee for Medical Research Ethics, Mid-Norway, and MINDMAP-specific approval was received from the same committee. LASA received ethical approval by the Medical Ethical Committee of the Vrije Universiteit medisch centrum. RECORD received ethical approval from the Commission Nationale de l’Informatique et des Libertés.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement MINDMAP-harmonised data are not publicly available. Access to harmonised data for MINDMAP researchers is requested through the MINDMAP coordinators and from individual cohort studies following existing data-access policies. CLSA study-specific data are available from the Canadian Longitudinal Study on Aging ( for researchers who meet the criteria for access to de-identified CLSA data.

  • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.

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