Swedish Covid-19 Investigation for Future Insights – A Population Epidemiology Approach Using Register Linkage (SCIFI-PEARL)

Abstract

Fredrik Nyberg,1 Stefan Franzén,1,2 Magnus Lindh,3,4 Lowie Vanfleteren,5,6 Niklas Hammar,7 Björn Wettermark,8 Johan Sundström,9,10 Ailiana Santosa,1 Staffan Björck,11 Magnus Gisslén3,12 1School of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 2National Diabetes Register, Centre of Registers Västra Götaland, Gothenburg, Sweden; 3Department of Infectious Diseases, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 4Department of Clinical Microbiology, Sahlgrenska University Hospital, Gothenburg, Sweden; 5COPD Center, Department of Respiratory Medicine and Allergology, Sahlgrenska University Hospital, Gothenburg, Sweden; 6Department of Internal Medicine and Clinical Nutrition, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden; 7Unit of Epidemiology, Institute of Environmental Medicine, Karolinska Institute, Stockholm, Sweden; 8Pharmacoepidemiology & Social Pharmacy, Department of Pharmacy, Uppsala University, Uppsala, Sweden; 9Clinical Epidemiology Unit, Department of Medical Sciences, Uppsala University, Uppsala, Sweden; 10The George Institute for Global Health, University of New South Wales, Sydney, Australia; 11Centre of Registers Västra Götaland, Gothenburg, Sweden; 12Region Västra Götaland, Department of Infectious Diseases, Sahlgrenska University Hospital, Gothenburg, SwedenCorrespondence: Fredrik NybergSchool of Public Health and Community Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Box 463, Gothenburg, 405 30, SwedenTel [phone]; [phone]Email [email protected]: In response to the Covid-19 pandemic, we designed and initiated a nationwide linked multi-register, regularly updated, observational study for timely response to urgent scientific questions.Aim: To describe the SCIFI-PEARL (Swedish Covid-19 Investigation for Future Insights – a Population Epidemiology Approach using Register Linkage) linked database encompassing essentially all known diagnosed Swedish Covid-19 patients plus a large general population comparison cohort and outline its utility in the current and future phases of the pandemic.Methods: Individuals with Covid-19 from the entire country are identified on a regularly updated basis, from different sources: all individuals from SmiNet, the national database of notifiable diseases, with positive SARS-CoV-2 polymerase chain reaction (PCR) test results; patients identified in the healthcare system by condition (ICD-10) or procedure codes in the National Patient Register or Cause-of-Death Register; patients identified through several disease-specific national quality registers (NQRs); and in two regions additionally patients identified in primary care. A comparison population was obtained by stratified random sampling from Swedish national population registers. Data from all these registers plus the National Prescribed Drug Register, the Cancer Register, national sociodemographic registers, some additional NQRs, the National Vaccination Register, and further data sources, are then linked to all study subjects (Covid-19 cases and population cohort). New cases in the study population and all data for all subjects are updated every few months, as required.Conclusion and Utility: The SCIFI-PEARL study cohort captures Swedish residents with Covid-19 on an ongoing basis, includes a representative general population comparison cohort, and links to a broad range of national and regional healthcare data for a comprehensive longitudinal view of the Covid-19 pandemic. By combining high-quality national registers with short time delay and continuous repeated linkage and updating, the project brings timely and internationally relevant data for epidemiological research on SARS-CoV-2. Our efforts provide an example and important learnings for similar efforts internationally in the future.Keywords: SARS-CoV-2, population cohort, data updates, observational research, longitudinal

Keywords

• sars-cov-2 population cohort data updates observational research longitudinal