Clinical Epidemiology (May 2021)
Positive Predictive Value of Diagnostic Codes for Inflammatory Bowel Disease in the Danish National Patient Registry Among Individuals 50+ Years, Using Patient Records as Reference Standard
Abstract
Camilla Rye,1,2 Katrine Hass Rubin,2 Frederik Trier Moller,3,4 Mette Julsgaard,5 Tine Jess,6 Vibeke Andersen1,2,7 1Research Unit for Molecular Diagnostics and Clinical Research, Institute for Regional Health Research-Center of Southern Jutland, University Hospital of Southern Denmark, Aabenraa, Denmark; 2OPEN - Open Patient Data Explorative Network, Department of Clinical Research, University of Southern Denmark and Odense University Hospital, Odense, Denmark; 3Department of Epidemiological Research, Statens Serum Institute, Copenhagen, Denmark; 4Department of Infectious Disease Epidemiology and Prevention, Statens Serum Institute, Copenhagen, Denmark; 5Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark; 6Center for Clinical Research and Prevention, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; 7Institute of Molecular Medicine, University of Southern Denmark, Odense, DenmarkCorrespondence: Vibeke AndersenResearch Unit for Molecular Diagnostics and Clinical Research, University Hospital of Southern Denmark, Kresten Philipsens Vej 15, Aabenraa, DK-6200, DenmarkTel +45-21157790Email [email protected]: Inflammatory bowel diseases (IBD), including Crohn’s disease (CD) and ulcerative colitis (UC), are chronic diseases. The aim was to validate diagnoses of IBD among patients aged 50+ years in the Danish National Patient Registry (NPR) by comparison with patient medical records.Patients and Methods: Men and women in the Diet, Cancer and Health (DCH) cohort were linked to NPR, and cases with a diagnosis of IBD and their respective hospital records were identified. Validation was performed by comparing patient medical records with information on discharge diagnoses of IBD from the NPR.Results: Of 57,053 individuals in the DCH-cohort, 339 were registered with an IBD diagnosis in NPR, with 277 (82%) records available for review. Among 277 patients, the positive predictive values (PPVs) of one CD or UC registration in NPR were 78% for IBD overall, 51% for CD and 54% for UC. One hundred fifty-seven patients had at least two CD and/or UC registrations with PPVs of 90% for IBD overall, 65% for CD and 73% for UC. One hundred and two patients had at least three registrations with PPVs of 97% for IBD overall, 75% for CD and 88% for UC. 96% were diagnosed at a specialized department. Other diagnoses coded as IBD mostly included microscopic colitis, irritable bowel syndrome and cancer.Conclusion: Validity of IBD diagnoses in the registry of individuals aged 50+ years increased with the number of registrations. It is recommended that these results are taken into consideration in future studies, especially in epidemiology research using NPR as a data source for patients diagnosed with IBD.Keywords: inflammatory bowel disease, Danish National Patient Registry, register study, diagnostic accuracy, diagnosis
