Clinical Epidemiology (Aug 2018)
Intracerebral hemorrhage: positive predictive value of diagnosis codes in two nationwide Danish registries
Abstract
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
