title: Identifying rare diseases using electronic medical records: the example of allergic bronchopulmonary aspergillosis.
abstract: OBJECTIVE
  The purpose of the study is to evaluate whether primary care electronic medical records (EMRs) from patients with severe asthma can be used to identify allergic bronchopulmonary aspergillosis (ABPA) cases.
  
  
  METHODS
  This cross-sectional feasibility study was conducted in adults with active and severe asthma registered with the Clinical Practice Research Datalink. A set of keywords flagged terms potentially indicative of ABPA in free-text comments of patients' EMRs to produce a grid on the basis of keywords' hit or miss. The grid was examined for occurrence and concurrence of keywords to discern patterns of concurrence potentially indicative of an underlying diagnosis of ABPA.
  
  
  RESULTS
  The analyses included 3 653 169 free-text items from 21 054 patients. In total, 52 patients (0.25%) had at least one mention of 'ABPA' in their medical record; 67% of these patients also had a mention of 'aspergillus/aspergillosis', 54% of 'bronchiectasis', 42% of 'itraconazole' and 62% of 'IgE'. The term 'aspergillus/aspergillosis' occurred with a proportion of 1.84% (N = 387); 9% of these patients also had a mention of 'ABPA', and the remaining 91% were potential additional cases of ABPA. From the observed concurrence of keywords, we were able to devise a potential algorithm to identify cases with varying degrees of specificity.
  
  
  CONCLUSIONS
  This study suggests that analysis of free text within asthmatic patients' EMRs may be used to identify potential cases of ABPA. This could be an efficient approach to identify rare conditions and to quantify their potential burden. © 2017 The Authors. Pharmacoepidemiology & Drug Safety Published by John Wiley & Sons Ltd.
authors.affiliation: OXON Epidemiology Ltd, London, UK.|Department of Biomedical Sciences, University of Alcala de Henares, Madrid, Spain.
authors.forename: Andrew
authors.identifier: http://orcid.org/0000-0003-3563-4583
authors.initials: A
authors.lastname: Maguire
authors.affiliation: OXON Epidemiology Ltd, London, UK.
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Johnson
authors.affiliation: National Aspergillosis Centre, University Hospital of South Manchester, The University of Manchester, Manchester Academic Health Science Centre, Manchester, UK.
authors.forename: David W
authors.initials: DW
authors.lastname: Denning
authors.affiliation: Vaccine Discovery and Development, GSK Vaccines, Wavre, Belgium.
authors.forename: Germano L C
authors.initials: GLC
authors.lastname: Ferreira
authors.affiliation: Vaccine Discovery and Development, GSK Vaccines, Wavre, Belgium.
authors.forename: Adrian
authors.initials: A
authors.lastname: Cassidy
mesh_terms: D000328:Adult; D000935:Antifungal Agents / Q000627:therapeutic use; D001229:Aspergillosis, Allergic Bronchopulmonary / Q000175:diagnosis* / Q000188:drug therapy; D001249:Asthma / Q000150:complications; D057286:Electronic Health Records; D005260:Female; D006801:Humans; D008297:Male; D035583:Rare Diseases / Q000175:diagnosis*; D055815:Young Adult
chemical_list: D000935:Antifungal Agents
keywords: CPRD; allergic bronchopulmonary aspergillosis; burden; case definition; electronic medical records; pharmacoepidemiology; rare disease