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Anne Clausen,1,2 Sören Möller,1,2 Michael Kriegbaum Skjødt,1,3,4 Rasmus Bank Lynggaard,5 Pernille Just Vinholt,5,6 Martin Lindberg-Larsen,7 Jens Søndergaard,8 Bo Abrahamsen,1,4 Katrine Hass Rubin1,2 1Research Unit OPEN, Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 2OPEN - Open Patient Data Explorative Network, Odense University Hospital, Odense, Denmark; 3Department of Medicine, Herlev Hospital, Copenhagen, Denmark; 4Department of Medicine, Holbæk Hospital, Holbæk, Denmark; 5Department of Clinical Biochemistry, Odense University Hospital, Odense, Denmark; 6Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 7Department of Orthopaedic Surgery and Traumatology, Odense University Hospital, Odense, Denmark; 8The Research Unit of General Practice, Department of Public Health, University of Southern Denmark, Odense, DenmarkCorrespondence: Katrine Hass Rubin, Tel +45 21261966, Email Katrine.Rubin@rsyd.dkObjective: To evaluate the validity of diagnosis codes for Major Osteoporotic Fracture (MOF) in the Danish National Patient Registry (NPR) and secondly to evaluate whether the fracture was incident/acute using register-based definitions including date criteria and procedural codes.Methods: We identified a random sample of 2400 records with a diagnosis code for a MOF in the NPR with dates in the year of 2018. Diagnoses were coded with the 10th revision of the International Classification of Diseases (ICD-10). The sample included 2375 unique fracture patients from the Region of Southern Denmark. Medical records were retrieved for the study population and reviewed by an algorithmic search function and medical doctors to verify the MOF diagnoses. Register-based definitions of incident/acute MOF was evaluated in NPR data by applying date criteria and procedural codes.Results: The PPV for MOF diagnoses overall was 0.99 (95% CI: 0.98;0.99) and PPV=0.99 for the four individual fracture sites, respectively. Further, analyses of incident/acute fractures applying date criteria, procedural codes and using patients’ first contact in the NPR resulted in PPV=0.88 (95% CI: 0.84;0.91) for hip fractures, PPV=0.78 (95% CI: 0.74;0.83) for humerus fractures, PPV=0.78 (95% CI: 0.73;0.83) for clinical vertebral fractures and PPV=0.87 (95% CI: 0.83;0.90) for wrist fractures.Conclusion: ICD-10 coded MOF diagnoses are valid in the NPR. Furthermore, a set of register-based criteria can be applied to qualify if the MOF fracture was incident/acute. Thus, the NPR is a valuable and reliable data source for epidemiological research on osteoporotic fractures.Keywords: major osteoporotic fractures, validity, positive predictive value, the Danish National Patient Register, algorithmic search function, epidemiology

Søren Rattenborg,1,2 Sören Möller,3,4 Erik Frostberg,1,2 Hans B Rahr1,2,5 1Department of Surgery, Vejle Hospital, University Hospital of Southern Denmark, Vejle, Denmark; 2Colorectal Cancer Center South, Vejle, Denmark; 3Open Patient Data Exploratory Network, Odense University Hospital, Odense, Denmark; 4Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 5Institute of Regional Health Research, University of Southern Denmark, Odense, DenmarkCorrespondence: Søren Rattenborg, Department of Surgery, Vejle Hospital, Beriderbakken 4, Vejle, 7100, Denmark, Tel +45-79405000, Email soren.rattenborg@rsyd.dkPurpose: The purpose of this study was to elucidate between-hospital variation in the prevalence at the time of diagnosis of patient-related risk factors for adverse outcomes of colorectal cancer (CRC) treatment.Patients and Methods: A register-based national cohort of 44,471 patients diagnosed with CRC and registered in the Danish Colorectal Cancer Group database in 2009– 2018 was included in the study. Patient-related risk factors present at diagnosis were collected from national Danish registers within the areas of demography, lifestyle factors, comorbidity, participation in screening, disease-related factors and socioeconomic factors. Prediction models of short-term postoperative outcomes and mortality were modelled to examine the potential aggregated impact of patient-related risk factors on outcomes, and variations between hospitals were examined.Results: The most conspicuous variations found were for old age (75+ years), ranging from 31% (95% confidence interval (95% CI): 29– 33%) to 46% (95% CI: 43– 48%), Union for International Cancer Control Stage I ranging from 12% (95% CI: 10– 14%) to 21% (95% CI: 19– 22%), Stage IV ranging from 23% (95% CI: 21– 25%) to 35% (95% CI: 34– 37%) and American Society of Anesthesiologists score ≥III ranging from 18% (95% CI: 16– 19%) to 40% (95% CI: 37– 43%). Clinically significant variations were found in predicted probability of 30-day surgical complications which varied from 17% (95% CI: 16– 17%) to 23% (95% CI: 22– 23%) and 90-day postoperative mortality which varied between 3.2% (95% CI: 3– 3.4%) and 5.5% (95% CI: 4.9– 6%).Conclusion: Marked variation in the prevalence of patient-related risk factors for adverse outcomes of colorectal cancer treatment exists between hospitals in Denmark. It seems reasonable to take these differences into account when comparing outcomes between hospitals.Keywords: colorectal cancer, morbidity, mortality, risk factors, surgery

Vibeke Andersen,1– 3 Andreas Kristian Pedersen,1 Sören Möller,4 Anders Green4 1Focused Research Unit for Molecular Diagnostic and Clinical Research, University Hospital of Southern Denmark, Åbenrå, Denmark; 2Institute of Regional Research (IRS-Center Sonderjylland), University of Southern Denmark, Odense, Denmark; 3Institute of Molecular Medicine, University of Southern Denmark, Odense, Denmark; 4Open Patient Data Explorative Network (OPEN), Department of Clinical Research, Odense University Hospital and University of Southern Denmark, Odense, DenmarkCorrespondence: Vibeke AndersenFocused Research Unit for Molecular Diagnostic and Clinical Research, University Hospital of Southern Denmark, Aabenraa, Kresten Philipsens Vej 15, Åbenrå DK-6200, DenmarkEmail va@rsyd.dkBackground: Chronic inflammatory diseases (CIDs) may share aetiological factors across diseases. We used registry data to evaluate the risk of developing five common childhood CIDs dependent on the parents’ disease status.Methods: We performed a national population-based registry study by linking data from the national Danish health registers from January 1973 to March 2016 to evaluate any potential associations between parents’ disease and development of CIDs among the offspring. Results were adjusted for parental age at birth, the decade of birth, gender of the child, and type of birth. A cohort of 2,699,449 liveborn children was established for investigating the primary outcome measures: diabetes mellitus (DM), rheumatoid arthritis (RA), coeliac disease, Crohn’s disease (CD), and ulcerative colitis (UC) and all diseases combined (CID).Results: Children with one CID affected parent (Hazard ratio (HR), 95% confidence interval (95% CI)=1.75 (1.72– 1.79, p< 0.001)), one multiple CID affected parent (HR=2.23 (2.11– 2.34), p< 0.001), and both parents affected (HR=3.10 (2.98– 3.22), p< 0.001) were at higher risk than children without CID affected parents. Children with DM, RA, and COE affected parents were at increased risk of three specific diseases (DM, RA and COE), whereas children with CD and UC affected parents were at increased risk of two specific diseases (CD and UC).Conclusion: Children with CID affected parents were at increased risk of the same CID as their parents as well as other specific CIDs dependent on the parents’ CID. Future studies should address the aetiology underlying these findings to support the development of new strategies for prevention, treatment, and cure.Keywords: parents’ disease, population study, chronic inflammatory disease, inflammatory bowel diseases, rheumatoid arthritis, coeliac disease, diabetes mellitus

Dennis Lund Hansen,1,2 Sören Möller,1,3 Kjeld Andersen,1,4 David Gaist,1,5 Henrik Frederiksen1,2 1Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 2Department of Hematology, Odense University Hospital, Odense, Denmark; 3OPEN, Odense University Hospital, Odense, Denmark; 4Department of Psychiatry, Odense, Region of Southern Denmark, Odense, Denmark; 5Neurology Research Unit, Department of Neurology, Odense University Hospital, Odense, DenmarkCorrespondence: Dennis Lund Hansen Email dlh@dadlnet.dkBackground: Acquired hemolytic disorders—autoimmune hemolytic anemia (AIHA), cold agglutinin disease (CAD), paroxysmal nocturnal hemoglobinuria (PNH), drug-induced hemolysis (DIHA), and acquired hemolysis not otherwise specified (AHNOS)—are considered rare. Despite their potentially major health implications, data regarding their incidence and prevalence are scarce.Methods: To fill this gap we collected data regarding all patients with acquired hemolytic disorder diagnoses in 1977– 2016 from the Danish National Patient Register. These data were linked with vital and migration status information from the Danish Civil Registration System. From these data combined with annual demographic data for the background population, we calculated age- and sex-specific incidence rates and prevalence proportions of acquired hemolytic disorders for specified time periods.Results: Our analysis included 5868 patients with acquired hemolytic disorders (2715 with AIHA, 112 CAD, 397 DIHA, 116 PNH, and 2154 AHNOS). The incidence rates per 100 000 person-years in 1980– 1993 and 2008– 2016 were 0.81 and 1.77 for AIHA, 0.31 and 0.12 for DIHA, and 0.04 and 0.08 for PNH, respectively. The 2008– 2016 CAD incidence rate was 0.18/100 000 person-years, CAD diagnosis code was not defined before 1994. All incidence rates increased with age. The prevalence proportion per 100 000 persons in 1980 and 2015 was 2.52 and 17.01 for AIHA, 0.80 and 1.50 for DIHA, and 0.18 and 1.04 for PNH. CAD prevalence in 2015 was 1.04/100 000 persons.Conclusion: Acquired hemolytic anemia incidence rates and prevalence proportions with the exception of DIHA are markedly increasing.Keywords: autoimmune hemolytic anemia, cold agglutinin disease, paroxysmal nocturnal hemoglobinuria, drug-induced hemolytic anemia, incidence, prevalence

Dennis Lund Hansen,1,2 Andreas Glenthøj,3 Sören Möller,1,4 Bart J Biemond,5 Kjeld Andersen,1,6 David Gaist,1,7 Jesper Petersen,3 Henrik Frederiksen1,2 1Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 2Department of Hematology, Odense University Hospital, Odense, Denmark; 3Department of Hematology, Center for Hemoglobinopathies, Herlev and Gentofte Hospital, Herlev, Denmark; 4OPEN, Odense University Hospital, Odense, Denmark; 5Department of Hematology, Amsterdam University Medical Centre’s, Amsterdam, Netherlands; 6Department of Mental Health - Odense, Region of Southern Denmark, Odense, Denmark; 7Neurology Research Unit, Department of Neurology, Odense University Hospital, Odense, DenmarkCorrespondence: Dennis Lund Hansen Email dlh@dadlnet.dkBackground: Congenital red blood cell (RBC) disorders, such as hemoglobinopathies, are frequent worldwide but with large geographical variation. Growing migration has increased the number of patients with RBC disorders in formerly low prevalence countries, eg, Denmark. However, accurate prevalences are unknown.Methods: Patients with a registered diagnosis of congenital hemolysis in the Danish National Patient Register between 1977 and 2016 were linked to a national laboratory database of RBC disorders and the Danish civil registration system. We calculate annual age- and sex-specific prevalences of the congenital hemolytic disorders from 2000 to 2016.Results: Prevalences of all subtypes of congenital hemolytic disorders increased during the study period. The prevalence of hereditary spherocytosis increased 1.73 times between 2000 and 2015, from 10.2/105 persons to 17.7/105 persons. Alpha thalassemia trait had a prevalence of 0.5/105 persons in 2000, but increased 41 times to 19.2/105 persons in 2015. Beta thalassemia minor increased eightfold from 4.5/105 persons in 2000 to 34.9/105 persons in 2015. Likewise, sickle cell trait increased 11 times from 0.7/105 persons in 2000 to 8.1/105 persons in 2015, whereas sickle cell disease increased from 0.5/105 persons to 2.7/105 persons in 2015, a fivefold increase.Conclusion: The prevalence of congenital RBC disorders in Denmark is increasing. The hemoglobinopathy traits now have prevalences as high as hereditary spherocytosis. These estimates of congenital hemolytic disorders in Denmark emphasize that inborn hemoglobin disorders are a public health concern, even in some formerly low prevalence countries.Keywords: hemolytic anemia, thalassemia, sickle cell disease, hereditary spherocytosis, hemoglobinopathies, sickle cell anemia

Vibeke Andersen, 1–3 Sören Möller, 4 Peter Bjødstrup Jensen, 4 Frederik Trier Møller, 5, 6 Anders Green 4 1Focused Research Unit for Molecular Diagnostic and Clinical Research (MOK), Hospital of Southern Jutland, Åbenrå DK-6200, Denmark; 2Institute of Regional Research (IRS-Center Sonderjylland), University of Southern Denmark, Odense C DK-5000, Denmark; 3Institute of Molecular Medicine, University of Southern Denmark, Odense C DK-5000, Denmark; 4Open Patient data Explorative Network (OPEN), Department of Clinical Research, Odense University Hospital and University of Southern Denmark, Odense C DK-5000, Denmark; 5Department of Epidemiology Research, Statens Serum Institute, Copenhagen DK-2300, Denmark; 6Department of Infectious Disease Epidemiology and Prevention, Statens Serum Institute, Copenhagen DK-2300, DenmarkCorrespondence: Vibeke Andersen Email va@rsyd.dkBackground: Chronic inflammatory diseases in childhood and early adult life share aetiological factors operating from birth and onwards. In this study, we use data from the national Danish health registers to evaluate the risk of developing four common, immune-mediated hospital-diagnosed childhood chronic inflammatory diseases.Methods: A national population-based registry study. Data from the Danish Medical Birth Registry and the Danish National Patient Registry from January 1973 to March 2016 were linked at a personal level to evaluate any potential associations between caesarean section and development of Inflammatory bowel diseases, rheumatoid arthritis, coeliac disease and diabetes mellitus among the offspring. A model adjusted for parental age at birth, decade of birth, gender of child, and parents’ chronic inflammatory disease status was used.Results: This register-based national cohort study of 2672708 children with information on delivery mode found an increased risk of diabetes, arthritis, coeliac disease, and inflammatory bowel disease for both girls and boys after caesarean section compared with vaginal delivery. The higher risk was present at least 40 years after delivery. In a subgroup analysis, both acute and elective caesarean section was associated with an increased risk of developing a chronic inflammatory disease.Conclusions: Being born by caesarean section leads to increased host susceptibility for chronic inflammatory diseases that last for decades. This finding should be further addressed in future studies with the aim to support the development of new strategies for prevention, treatment, and maybe even cure.Keywords: caesarean delivery, population study, vaginal birth, chronic inflammatory disease, inflammatory bowel diseases, rheumatoid arthritis, coeliac disease

Jes Sloth Mathiesen,1,2 Jens Peter Kroustrup,3 Peter Vestergaard,3,4 Kirstine Stochholm,5,6 Per Løgstrup Poulsen,6 Åse Krogh Rasmussen,7 Ulla Feldt-Rasmussen,7 Sten Schytte,8 Stefano Christian Londero,8 Henrik Baymler Pedersen,9 Christoffer Holst Hahn,10 Jens Bentzen,11 Sören Möller,2,12 Mette Gaustadnes,13 Maria Rossing,14 Finn Cilius Nielsen,14 Kim Brixen,2 Anja Lisbeth Frederiksen,2,15 Christian Godballe1 On behalf of the Danish Thyroid Cancer Group (DATHYRCA) 1Department of ORL Head & Neck Surgery and Audiology, Odense University Hospital, Odense, Denmark; 2Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 3Department of Clinical Medicine and Endocrinology, Aalborg University Hospital, Aalborg, Denmark; 4Steno Diabetes Center North Jutland, Aalborg, Denmark; 5Department of Internal Medicine and Endocrinology, Aarhus University Hospital, Aarhus, Denmark; 6Center for Rare Diseases, Aarhus University Hospital, Aarhus, Denmark; 7Department of Medical Endocrinology, Copenhagen University Hospital, Copenhagen, Denmark; 8Department of ORL Head and Neck Surgery, Aarhus University Hospital, Aarhus, Denmark; 9Department of ORL Head & Neck Surgery, Aalborg University Hospital, Aalborg, Denmark; 10Department of ORL Head & Neck Surgery, Copenhagen University Hospital, Copenhagen, Denmark; 11Department of Oncology, Herlev Hospital, Herlev, Denmark; 12Odense Patient data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark; 13Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark; 14Center for Genomic Medicine, Copenhagen University Hospital, Copenhagen, Denmark; 15Department of Clinical Genetics, Odense University Hospital, Odense, Denmark Background: The completeness of REarranged during Transfection (RET) testing in patients with medullary thyroid carcinoma (MTC) was recently reported as 60%. However, the completeness on a population level is unknown. Similarly, it is unknown if the first Danish guidelines from 2002, recommending RET testing in all MTC patients, improved completeness in Denmark. We conducted a nationwide retrospective cohort study aiming to evaluate the completeness of RET testing in the Danish MTC cohort. Additionally, we aimed to assess the completeness before and after publication of the first Danish guidelines and characterize MTC patients who had not been tested.Methods: The study included 200 patients identified from the nationwide Danish MTC cohort 1997–2013. To identify RET tested MTC patients before December 31, 2014, the MTC cohort was cross-checked with the nationwide Danish RET cohort 1994–2014. To characterize MTC patients who had not been RET tested, we reviewed their medical records and compared them with MTC patients who had been tested.Results: Completeness of RET testing in the overall MTC cohort was 87% (95% CI: 0.81–0.91; 173/200). In the adjusted MTC cohort, after excluding patients diagnosed with hereditary MTC by screening, completeness was 83% (95% CI: 0.76–0.88; 131/158). Completeness was 88% (95% CI: 0.75–0.95; 42/48) and 81% (95% CI: 0.72–0.88) (89/110) before and after publication of the first Danish guidelines, respectively. Patients not RET tested had a higher median age at diagnosis compared to those RET tested. Median time to death was shorter in those not tested relative to those tested.Conclusion: The completeness of RET testing in MTC patients in Denmark seems to be higher than reported in other cohorts. No improvement in completeness was detected after publication of the first Danish guidelines. In addition, data indicate that advanced age and low life expectancy at MTC diagnosis may serve as prognostic indicators to identify patients having a higher likelihood of missing the compulsory RET test. Keywords: RET testing, medullary thyroid carcinoma, Denmark

Jes Sloth Mathiesen,1,2 Jens Peter Kroustrup,3 Peter Vestergaard,3,4 Kirstine Stochholm,5,6 Per Løgstrup Poulsen,5 Åse Krogh Rasmussen,7 Ulla Feldt-Rasmussen,7 Sten Schytte,8 Henrik Baymler Pedersen,9 Christoffer Holst Hahn,10 Jens Bentzen,11 Sören Möller,2,12 Mette Gaustadnes,13 Maria Rossing,14 Finn Cilius Nielsen,14 Kim Brixen,2 Anja Lisbeth Frederiksen,2,15 Christian Godballe1 1Department of ORL Head & Neck Surgery and Audiology, Odense University Hospital, Odense, Denmark; 2Department of Clinical Research, University of Southern Denmark, Odense, Denmark; 3Department of Clinical Medicine and Endocrinology, Aalborg University Hospital, Aalborg, Denmark; 4Steno Diabetes Center North Jutland, Aalborg, Denmark; 5Department of Internal Medicine and Endocrinology, Aarhus University Hospital, DK-8000 Aarhus, Denmark; 6Center for Rare Diseases, Aarhus University Hospital, Aarhus N, Denmark; 7Department of Medical Endocrinology, Copenhagen University Hospital, Copenhagen, Denmark; 8Department of ORL Head and Neck Surgery, Aarhus University Hospital, Aarhus, Denmark; 9Department of ORL Head and Neck Surgery, Aalborg University Hospital, Aalborg, Denmark; 10Department of ORL Head and Neck Surgery, Copenhagen University Hospital, Copenhagen, Denmark; 11Department of Oncology, Herlev Hospital, Herlev, Denmark; 12Odense Patient data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark; 13Department of Molecular Medicine, Aarhus University Hospital, Aarhus, Denmark; 14Center for Genomic Medicine, Copenhagen University Hospital, Copenhagen, Denmark; 15Department of Clinical Genetics, Odense University Hospital, Odense, Denmark Background: The incidence and prevalence of multiple endocrine neoplasia 2A (MEN2A) have only been reported once in a nationwide setting. However, it is unclear whether the figures are representative of other populations, as the major component of the syndrome, hereditary medullary thyroid carcinoma (MTC), has been reported as rare in the same country. We conducted a nationwide retrospective cohort study of MEN2A in Denmark from 1901 to 2014, aiming to describe the incidence and prevalence. Methods: This study included 250 unique MEN2A patients born or resident in Denmark before December 31, 2014. Patients were identified through the Danish REarranged during Transfection (RET) cohort, linkage of MEN2A pedigrees, the Danish MTC cohort, a nationwide collaboration of MEN2 centers, cross-checking of other relevant cohorts, and a systematic literature search. Results: The incidence from 1971 to 2000 was 28 (95% CI: 21–37) per million live births per year. Incidence for the specific mutations or for the overall MEN2A group did not change significantly from 1901 to 2014 (P>0.05). Point prevalence at January 1, 2015, was 24 per million (95% CI: 20–28). Conclusion: The incidence and prevalence of MEN2A in Denmark seem higher than those reported in other countries. This is likely explained by the Danish C611Y founder effect. Also, our data indicate no significant change in MEN2A incidence during the last century. Keywords: multiple endocrine neoplasia 2A, incidence, prevalence, Denmark

Stine Munk Hald,1,2 Christine Kring Sloth,1,2 Sabine Morris Hey,1,2 Charlotte Madsen,1 Nina Nguyen,3 Luis Alberto García Rodríguez,4 Rustam Al-Shahi Salman,5 Sören Möller,2,6 Frantz Rom Poulsen,7 Anton Pottegård,8 David Gaist1,2,6 1Department of Neurology, Odense University Hospital, Odense, Denmark; 2Department of Clinical Research, Faculty of Health Sciences, University of Southern Denmark, Odense, Denmark; 3Department of Radiology, Odense University Hospital, Odense, Denmark; 4Spanish Centre for Pharmacoepidemiologic Research (CEIFE), Madrid, Spain; 5Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, UK; 6Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark; 7Department of Neurosurgery, Odense University Hospital, Odense, Denmark; 8Clinical Pharmacology and Pharmacy, Department of Public Health, University of Southern Denmark, Odense, Denmark Purpose: The purpose of this study is to establish the validity of intracerebral hemorrhage (ICH) diagnoses in the Danish Stroke Registry (DSR) and the Danish National Patient Registry (DNPR).Patients and methods: We estimated the positive predictive value (PPV) of ICH diagnoses for a sample of 500 patients from the DSR (patients recorded under ICH diagnosis) and DNPR (International Classification of Diseases, version 10, code I61) during 2010–2015, using discharge summaries and brain imaging reports (minimal data). We estimated PPVs for any ICH (a-ICH) and spontaneous ICH (s-ICH) alone. Furthermore, we assessed PPVs according to whether patients were recorded in both or only one of the registries. Finally, in a subsample with ICH diagnoses with access to full medical records and original imaging studies (extensive data, n=100), we compared s-ICH diagnosis and hemorrhage location after use of extensive vs minimal data.Results: In the DSR, the PPVs were 94% (95% CI, 91%–96%) for a-ICH and 85% (95% CI, 81%–88%) for s-ICH. In the DNPR, the PPVs were 88% (95% CI, 84%–91%) for a-ICH and 75% (95% CI, 70%–79%) for s-ICH. PPVs for s-ICH for patients recorded in both registries, DSR only, and DNPR only were 86% (95% CI, 82–99), 80% (95%CI, 71–87), and 49% (95%CI, 39–59), respectively. Evaluation of extensive vs minimal data verified s-ICH diagnosis in 98% and hemorrhage location in 94%.Conclusion: The validity of a-ICH diagnoses in DSR and DNPR is sufficiently high to support their use in epidemiologic studies. For s-ICH, validity was high in DSR. In DNPR, s-ICH validity was lower, markedly so for the small subgroup of patients only recorded in this registry. Minimal data including discharge summaries and brain imaging reports were feasible and valid for identifying ICH location. Keywords: stroke, epidemiology, register-based research, intracranial hemorrhage

We report on the design of a cryogenic setup for trapped ion quantum computing containing a segmented surface electrode trap. The heat shield of our cryostat is designed to attenuate alternating magnetic field noise, resulting in 120 dB reduction of 50 Hz noise along the magnetic field axis. We combine this efficient magnetic shielding with high optical access required for single ion addressing as well as for efficient state detection by placing two lenses each with numerical aperture 0.23 inside the inner heat shield. The cryostat design incorporates vibration isolation to avoid decoherence of optical qubits due to the motion of the cryostat. We measure vibrations of the cryostat of less than ±20 nm over 2 s. In addition to the cryogenic apparatus, we describe the setup required for an operation with 40Ca+ and 88Sr+ ions. The instability of the laser manipulating the optical qubits in 40Ca+ is characterized by yielding a minimum of its Allan deviation of 2.4 ⋅ 10-15 at 0.33 s. To evaluate the performance of the apparatus, we trapped 40Ca+ ions, obtaining a heating rate of 2.14(16) phonons/s and a Gaussian decay of the Ramsey contrast with a 1/e-time of 18.2(8) ms.