title: Categorization of allergic disorders in the new World Health Organization International Classification of Diseases.
abstract: BACKGROUND
  Although efforts to improve the classification of hypersensitivity/allergic diseases have been made, they have not been considered a top-level category in the International Classification of Diseases (ICD)-10 and still are not in the ICD-11 beta phase linearization. ICD-10 is the most used classification system by the allergy community worldwide but it is not considered as appropriate for clinical practice. The Systematized Nomenclature of Medicine Clinical Terms (SNOMED CT) on the other hand contains a tightly integrated classification of hypersensitivity/allergic disorders based on the EAACI/WAO nomenclature and the World Health Organization (WHO) may plan to align ICD-11 with SNOMED CT so that they share a common ontological basis.
  
  
  METHODS
  With the aim of actively supporting the ongoing ICD-11 revision and the optimal practice of Allergology, we performed a careful comparison of ICD-10 and 11 beta phase linearization codes to identify gaps, areas of regression in allergy coding and possibly reach solutions, in collaboration with committees in charge of the ICD-11 revision.
  
  
  RESULTS
  We have found a significant degree of misclassification of terms in the allergy-related hierarchies. This stems not only from unclear definitions of these conditions but also the use of common names that falsely imply allergy. The lack of understanding of the immune mechanisms underlying some of the conditions contributes to the difficulty in classification.
  
  
  CONCLUSIONS
  More than providing data to support specific changes into the ongoing linearization, these results highlight the need for either a new chapter entitled Hypersensitivity/Allergic Disorders as in SNOMED CT or a high level structure in the Immunology chapter in order to make classification more appropriate and usable.
authors.affiliation: Hospital Sírio Libanês, São Paulo, Brazil.
authors.forename: Luciana Kase
authors.initials: LK
authors.lastname: Tanno
authors.affiliation: Section of Allergy and Clinical Immunology, Imperial College London, National Heart and Lung Institute, Royal Brompton Hospital, London, UK.
authors.forename: Moises A
authors.initials: MA
authors.lastname: Calderon
authors.affiliation: Director, Kaiser-Permanente Southern California Regional Allergy-Immunology Laboratory, Consultant terminologist, International Health Terminology Standards Development Organization, Los Angeles, CA USA.
authors.forename: Bruce J
authors.initials: BJ
authors.lastname: Goldberg
authors.affiliation: Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Christine Kühne-Center for Allergy Research and Education, Davos, Switzerland.
authors.forename: Cezmi A
authors.initials: CA
authors.lastname: Akdis
authors.affiliation: Department of Allergy, 2nd Pediatric Clinic, University of Athens, Athens, Greece.
authors.forename: Nikolaos G
authors.initials: NG
authors.lastname: Papadopoulos
authors.affiliation: UPMC Paris 06, UMR-S 1136, IPLESP, Equipe EPAR, University Hospital of Montpellier, Montpellier, and Sorbonne Universités, 75013 Paris, France.
authors.forename: Pascal
authors.initials: P
authors.lastname: Demoly
keywords: Allergic diseases; Classification; Hypersensitivity diseases; International Classification of Diseases (ICD)