ICD-11 extension codes support detailed clinical abstraction and comprehensive classification

Saskia E. Drösler, Stefanie Weber, Christopher G. Chute

Research output: Contribution to journalReview articlepeer-review


Background: The new International Classification of Diseases—11th revision (ICD-11) succeeds ICD-10. In the three decades since ICD-10 was released, demands for detailed information on the clinical history of a morbid patient have increased. Methods: ICD-11 has now implemented an addendum chapter X called “Extension Codes”. This chapter contains numerous codes containing information on concepts including disease stage, severity, histopathology, medicaments, and anatomical details. When linked to a stem code representing a clinical state, the extension codes add significant detail and allow for multidimensional coding. Results: This paper discusses the purposes and uses of extension codes and presents three examples of how extension codes can be used in coding clinical detail. Conclusion: ICD-11 with its extension codes implemented has the potential to improve precision and evidence based health care worldwide.

Original languageEnglish (US)
Article number278
JournalBMC medical informatics and decision making
StatePublished - Nov 2021


  • Classification
  • Extension codes
  • ICD11
  • International Classification of Diseases

ASJC Scopus subject areas

  • Health Policy
  • Health Informatics


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