title: Validation of celiac disease diagnoses recorded in the Danish National Patient Register using duodenal biopsies, celiac disease-specific antibodies, and human leukocyte-antigen genotypes.
abstract: OBJECTIVE
  The purpose of this study was to validate the celiac disease diagnoses recorded in the Danish National Patient Register. To validate the diagnoses, we used information on duodenal biopsies from a national register of pathology reports (the Patobank) and information on celiac disease-specific antibodies and human leukocyte antigen (HLA) genotypes obtained from patient medical records.
  
  
  METHODS
  We included all the children who were born from 1995 to 2012 and who were registered as having celiac disease in the Danish National Patient Register. We reviewed all the pathology reports on duodenal biopsies in the Patobank and the information in the medical records on celiac disease-specific antibodies (ie, anti-tissue transglutaminase 2 IgA and IgG, endomysial antibodies IgA, and anti-deamidated gliadin peptide IgG) and HLA genotypes.
  
  
  RESULTS
  We identified 2,247 children who were registered in the Danish National Patient Register with celiac disease. Duodenal biopsies for 1,555 of the children (69%) were registered in the Patobank; 1,127 (50%) had a biopsy that was compatible with celiac disease (ie, Marsh 2-3). We accessed the medical records of 95% of the children who were registered in the Danish National Patient Register with celiac disease. We found that 1,510 (67%) had one or more positive antibody-test results; 1,120 (50%) had anti-tissue transglutaminase 2, IgA at tenfold or greater the upper limit of the normal range and/or positive endomysial antibody results. The positive predictive value depended on the criteria used for validation and the types and numbers of registrations that were included in the analysis and ranged from 62% (95% confidence interval: 60%-64%) to 86% (95% confidence interval: 84%-87%).
  
  
  CONCLUSIONS
  Our findings indicate that the Danish National Patient Register is a valuable source to identify patients who have been diagnosed with celiac disease. However, validation of the diagnoses is warranted before data on the patients are used for research purposes.
authors.affiliation: Hans Christian Andersen Children's Hospital, Odense University Hospital; Institute of Clinical Research, University of Southern Denmark; Odense Patient Data Explorative Network (OPEN), Odense University Hospital, Odense, Denmark.
authors.forename: Stine
authors.initials: S
authors.lastname: Dydensborg Sander
authors.affiliation: Mental and Physical Health, Norwegian Institute of Public Health, Oslo; Department of Pediatrics, Ostfold Hospital Trust, Fredrikstad, Norway.
authors.forename: Ketil
authors.initials: K
authors.lastname: Størdal
authors.affiliation: Department of Pathology, Hvidovre Hospital.
authors.forename: Tine
authors.initials: T
authors.lastname: Plato Hansen
authors.affiliation: Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Anne-Marie
authors.initials: AM
authors.lastname: Nybo Andersen
authors.affiliation: Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, MN, USA.
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Murray
authors.affiliation: Department of Clinical Immunology, Odense University Hospital, Odense, Denmark.
authors.forename: Søren Thue
authors.initials: ST
authors.lastname: Lillevang
authors.affiliation: Hans Christian Andersen Children's Hospital, Odense University Hospital; Institute of Clinical Research, University of Southern Denmark.
authors.forename: Steffen
authors.initials: S
authors.lastname: Husby
keywords: administrative health register; histology; medical record; national patient register; pathology register; serology