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. 2021 Jul 30:13:649-659.
doi: 10.2147/CLEP.S312742. eCollection 2021.

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

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 Gisslén  3   12
Affiliations

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

Fredrik Nyberg et al. Clin Epidemiol. .

Abstract

Background: 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; data updates; longitudinal; observational research; population cohort.

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Conflict of interest statement

Dr. Nyberg reports prior employment at AstraZeneca until 2019, and ownership of some AstraZeneca shares. Dr. Vanfleteren reports grants and personal fees from AstraZeneca, personal fees from Novartis, GSK, Chiesi, Menarini, Pulmonx, Resmed, Boehringer, Verona Pharma, AGA Linde outside the submitted work. Dr. Sundström reports ownership in companies providing services to Itrim, Amgen, Janssen, Novo Nordisk, Eli Lilly, Boehringer, Bayer, Pfizer and AstraZeneca, outside the submitted work. Dr. Gisslén reports personal fees from Gilead, personal fees from GSK/ViiV, personal fees from MSD, other from Gilead, other from GSK/ViiV, personal fees from Biogen, personal fees from Novocure, personal fees from Amgen, personal fees from Novo Nordisk, outside the submitted work. Dr. Lindh, Dr. Santosa, Dr. Franzén, Dr. Wettermark, Dr Björck and Dr. Hammar have nothing to disclose.

Figures

Figure 1
Figure 1
Structure of SCIFI-PEARL database. Included registers; identification of study population of COVID-19 patients (blue arrows) and general population sample (purple arrow); followed by linkage to all registers for relevant data from each register.
Figure 2
Figure 2
Age distribution of study subjects in SCIFI-PEARL based on initial October 2020 database for population comparison cohort, test-positive covid-19 patients and hospitalized covid-19 patients.
See this image and copyright information in PMC

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