Bibliografisk note

Funding Information:
This nationwide study used a registry-based follow-up design. Thirty-day OHCA survivors who were at least 18 years of age were identified using Danish Cardiac Arrest Registry data from 2001-2015, and age- and sex-matched population controls were identified using the Danish Civil Registration System. Neither the 30-day survivors nor the population controls had preexisting stroke, AF, ACS, or HF. Furthermore, the 30-day survivors included had not received a diagnosis of stroke, AF, ACS, or HF within 30 days from OHCA. Stroke was defined from diagnosis of ischaemic stroke. Known chronic ischaemic heart disease (IHD) and previous transient ischaemic attack (TIA) was allowed. In Denmark, all residents have a unique Civil Personal Registration Number, which is used in all health care contacts as well as reported to the Danish Cardiac Arrest Registry, enabling linkage between nationwide registries. 12 Follow-up data were also obtained from these nationwide registries. Information on patients’ age and sex was obtained from the Danish Civil Personal Registry, and data on the date and year of cardiac arrest were obtained from the Danish Cardiac Arrest Registry. Data on comorbidity and medication use before arrest were retrieved from the Danish National Patient Registry and the Danish National Prescription Registry and were defined based on International Classification of Diseases, Tenth Revision (ICD-10) codes and Anatomical Therapeutic Chemical Classification System (ATC) codes, respectively (Supplemental Table 1). 13,14 Comorbidity data consisted of hypertension, diabetes, chronic obstructive pulmonary disease (COPD), peripheral artery disease (PAD), IHD, TIA, and thyroid disease, and we also used information on antihypertensive drugs, antidiabetics, and selected inhalation drugs (anticholinergic and long-acting beta-agonists) from the Danish National Prescription Registry to define hypertension, diabetes, and COPD, respectively. To fulfill the definition of hypertension, at least two antihypertensive drug redemptions were required. Medication data included lipid-lowering-, antiplatelet-, and anticoagulant agents. Information on discharge diagnoses was collected for the 10 years preceding the index cardiac arrest and until day 30 post cardiac arrest; and data on prescription redemptions were collected for the last 180 days prior to the index cardiac arrest. The study was approved by the Danish Data Protection Agency. The Danish National Committee on Health Research Ethics does not require ethical approval for registry-based studies. The Danish Heart Foundation and The Danish Foundation TrygFonden provided financial support. None of these institutions have commercial interests in the field of cardiac arrest, and none of them had any influence on study design or conduct; collection, management, analysis, or interpretation of the data; or preparation, review, or approval of the manuscript for submission. The use of the Danish Cardiac Arrest Registry and other national registries used for the conduct of this study was approved by the Data Responsible Unit in the Capital Region of Denmark (P-2019–400).

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© 2021 The Author(s)