SEPLINE: Socioeconomic Position in Epidemiological Research—A National Guideline on Danish Registry Data

Cathrine F Hjorth,1 Thora M Kjærulff,2 Mette K Thomsen,1,3 Deirdre Cronin-Fenton,1 Susanne O Dalton,4– 6 Maja H Olsen,4 The SEPLINE Group includes:Anne Dahl Sørensen, Cathrine F. Hjorth, Danni Chen, Deirdre Cronin Fenton, Eeva-Liisa Røssell Johansen, Emma Neble Larsen, Frederik Nicolai Foldager, Gitte Valentin, Henrik Bøggild, Henrik Toft Sørensen, Henry Jensen, Ingelise Andersen, Jan Wohlfahrt, Jarl Christian Quitzau, Julie A. Schmidt, Kirubakaran Balasubramaniam, Lars Børty Nielsen, Lau Caspar Thygesen, Linda Ejlskov, Line Virgilsen, Maja Halgren Olsen, Marie Mørk Josiasen, Merete Osler, Mette Bender, Mette Kielsholm Thomsen, Michael Green, Nasrin Tayyari, Nynne Bech Utoft, Oleguer Plana-Ripoll, Peter Haastrup, Peter Vedsted, Pia Kjær Kristensen, Susanne Oksbjerg Dalton, Susanne Fogh Jørgensen, Søren Korsgaard Martiny, Thomas Maribo, Thomas Wolff Rosenqvist, Thora Majlund Kjærulff, Tinne Laurberg, Trine Allerslev Horsbøl, Ulla Arthur Hvidtfeldt, Ulrik Deding On behalf of the SEPLINE GroupPhD student, Research Unit for General Practice, Aarhus, Denmark, and Department of Public Health, Aarhus University, Denmark; Postdoc, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; PhD Student, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Professor, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Postdoc, Department of Public Health, Aarhus University and Steno Diabetes Center Aarhus, Denmark; PhD Student, Cancer Survivorship, Danish Cancer Institute, Denmark; PhD Student, Department of Orthopedic Surgery, Aarhus University & Aarhus University Hospital, Denmark; Researcher, DEFACTUM, Central Denmark Region, Denmark; Associate Professor, Public Health and Epidemiology, Department of Health Science and Technology, Aalborg University, Gistrup, Denmark & Research Data and Biostatistics, Aalborg University Hospital, Denmark; Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Epidemiologist, The Danish Healthcare Quality Institute (DHQI), Denmark; Associate Professor, Section of Social Medicine, Department of Public Health, University of Copenhagen, Denmark; Chief Epidemiologist, Cancer Epidemiology and Surveillance, Danish Cancer Institute & Department of Clinical Medicine, Aalborg University, Denmark; Chief Advisor, Statistics Denmark, Denmark; Postdoc, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Associate Professor, Research Unit of General Practice, University of Southern Denmark, Denmark; Assistant Professor, Center for Clinical Data Science, Aalborg University Hospital and Aalborg University, Denmark; Professor, National Institute of Public Health, University of Southern Denmark, Denmark; Assistant professor, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Senior Researcher, Research Unit for General Practice, Aarhus, Denmark; Postdoc, Cancer Survivorship, Danish Cancer Institute, Denmark; Department of Public Health, Aarhus University, Denmark; Professor, Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospitals and Section of Epidemiology, University of Copenhagen, Denmark; Assistant Professor, Section of Social Medicine, University of Copenhagen, Denmark; Postdoc, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital & CASTLE – Cancer Survivorship and Treatment Late Effects, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Denmark; Department of Obstetrics and Gynecology, Duke University School of Medicine, US; Researcher and Assistant Professor, DEFACTUM, Central Denmark Region and Aalborg University, Denmark; PhD Student, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Professor, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark & National Centre for Register-based Research, Department of Public Health, Aarhus University, Denmark; Associate Professor, Research Unit of General Practice, University of Southern Denmark, Denmark; Professor, Research Unit for General Practice, Aarhus and Medical Diagnostic Center, University Clinic for Innovative Patient Pathways, Department of Clinical Medicine, Aarhus University, Denmark; Associate Professor, Department of Orthopedic Surgery, Aarhus University and Aarhus University Hospital, Denmark; Professor, Cancer Survivorship, Danish Cancer Institute & Danish Research Center for Equality in Cancer (COMPAS), Department of Clinical Oncology and Palliative Care, Zealand University Hospital & Institute of Clinical Medicine, Faculty of Health, Copenhagen University, Denmark; Assistant Professor, Research Unit for Screening and Epidemiology, Department of Biochemistry and Immunology, Lillebaelt Hospital and Department of Regional Health Research, University of Southern Denmark, Denmark; PhD Student, Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Denmark; Professor, Department of Public Health, Aarhus University and DEFACTUM, Central Denmark Region, Denmark; PhD student, Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg, Denmark; Postdoc, National Institute of Public Health, University of Southern Denmark, Denmark; Associate Professor, Steno Diabetes Center Aarhus, Denmark; Associate Professor, National Institute of Public Health, University of Southern Denmark, Denmark; Senior Scientist, Work, Environment and Cancer, Danish Cancer Institute, Denmark; Postdoc, Epidemiologist, Department of Surgery, Odense University Hospital, & Department of Clinical Research, University of Southern Denmark, Denmark; 1Department of Clinical Epidemiology, Department of Clinical Medicine, Aarhus University and Aarhus University Hospital, Aarhus, Denmark; 2National Institute of Public Health, University of Southern Denmark, Odense, Denmark; 3CASTLE – Cancer Survivorship and Treatment Late Effects, Department of Oncology, Copenhagen University Hospital, Rigshospitalet, Copenhagen, Denmark; 4Cancer Survivorship, Danish Cancer Institute, Copenhagen, Denmark; 5Department of Clinical Oncology and Palliative Care, Zealand University Hospital, Næstved, Denmark; 6Institute of Clinical Medicine, Faculty of Health, Copenhagen University, Copenhagen, DenmarkCorrespondence: Cathrine F Hjorth, Email [email protected] Maja H Olsen, Email [email protected]: Socioeconomic differences in health have become an increasing public health concern and priority, leading to a growing number of studies investigating the relationship between socioeconomic position and health outcomes. However, variability in methodological practices hampers the comparability of findings and leads to inefficiencies, as researchers invest substantial resources in selecting appropriate variables and methods. To address these challenges, the SEPLINE initiative was established to develop a methodological guideline aimed at enhancing the comparability, quality, and feasibility of socioeconomic research using Danish registry data.Methods: The guideline was developed through a consensus-driven approach involving an interdisciplinary group of stakeholders from Danish universities, research institutions, and data warehouses. The guideline addresses socioeconomic position as an exposure based on data from Danish registries, with the cancer continuum applied as a case outcome to illustrate its application. The development process included two collaborative workshops informed by a pre-workshop questionnaire. Workshop I (spring 2024) focused on socioeconomic indicators, data collection, and data management, featuring expert presentations and group discussions. Workshop II (fall 2024) addressed analytical methods, including causal inference challenges and income/wealth assessment methods. Insights from these workshops were integrated into iterative refinements of the guideline.Conclusions and Implications: The guideline provides a structured framework for conducting socioeconomic epidemiological research using Danish registry data, offering specific information on data sources and recommendations about variable selection, measurement timing, and data handling. While tailored to Danish registry-based cancer research, the guideline’s methodological principles have broader applicability to other diseases and international contexts. By emphasizing transparency, theoretical grounding, and methodological rigor, SEPLINE aims to advance the study of social determinants of health. Researchers are encouraged to use the guideline as a relevant starting point and adapt it to their specific study populations and research questions, ensuring its relevance across diverse settings.Keywords: socioeconomic position, social epidemiology, methodology, social determinants of health, socioeconomic inequality, disparity, guideline, registry-based research