Updated Disease Classification System Adopted by the World Health Organization

31 May 2019

ILDS contributes to this landmark standard which includes over 2,000 separate skin disorders

2019.03.28 WHO ICD11 And ILDS Edit
The ILDS-WHO Committee and WHO ICD-11 Team in Geneva, March 2019

On 25 May 2019, the World Health Assembly[1] officially adopted the eleventh revision of the International Classification of Diseases (ICD-11). The ICD-11 will come into effect on 1 January 2022.


The adoption of ICD-11 is a milestone event, the development of which has taken the commitment of many experts over more than 10 years. The ILDS is very proud that ICD-11 represents the first time that dermatologists have been directly involved in developing a classification system that accurately reflects the unique and diverse spectrum of skin disorders seen around the world and, as such, ICD-11 will be a useful and relevant tool for dermatologists.


What is ICD-11 and how does it differ from its predecessors?

The ICD is the foundation for identifying health trends and statistics worldwide. It provides a common language that allows health professionals to record and share information on injuries, diseases and causes of death. ICD-11 takes into account the burden of disease and not just mortality and has a variety of uses including monitoring the incidence and prevalence of diseases, as well as safety and quality guidelines. It can be incorporated into electronic health records in addition to its use for collecting mortality and morbidity data.


ICD-11 is fundamentally different from its predecessors and comprises two elements: the ICD-11 Foundation, and ICD-11 for Mortality and Morbidity Statistics (MMS).

  • The ICD-11 Foundation is a family of classifications which are polyhierarchical; any one disease concept has a single Unique Identifier (URI) but may have multiple hierarchical parents, so that it can be classified within and retrieved from more than one location.
  • ICD-11 MMS is the direct replacement for ICD-10 as the international statistical reference and provides a concise list of entities from the ICD-11 Foundation.


ICD-11 defines the universe of diseases, disorders, injuries and other related health conditions, listed in a comprehensive, hierarchical fashion that allows for:

  • easy storage, retrieval and analysis of health information for evidenced-based decision-making;
  • sharing and comparing health information between hospitals, regions, settings and countries; and
  • data comparisons in the same location across different time periods.


Overall, ICD-11:

  • has improved usability – more clinical detail with less training time
  • has updated scientific content
  • enables coding of all clinical detail
  • is eHealth ready for use in electronic environments
  • is linked to other relevant classifications and terminologies (such as INN)
  • has full multilingual support (translations and outputs)
  • takes diseases morbidity and not only mortality into account, a new feature of ICD of such relevance for skin disease


How have dermatologists been involved in the development of ICD-11?

The ILDS has been involved in the revision since 2008 when we were invited to be the ICD-11 Dermatology Topic Advisory Group (TAG) leader. Over the last decade, the TAG has overseen the revision of the Diseases of the Skin chapter as well as many dermatologically relevant diseases located in other chapters of ICD. There are now over 2,000 different defined skin disorders that have been characterized as part of the ICD-11 development process.


A new logically ordered structure for the Diseases of the Skin chapter was developed by the TAG following wide consultation and accepted by World Health Organization (WHO) in 2010. More recently, ILDS members participated in field-testing of ICD-11 in 2017. Over 80 dermatologists from around the world responded to our request for input. They were asked to judge whether the diagnoses of 50 unselected patients they had recently seen could be adequately coded using ICD 11. Suitable diagnostic terms were found for 98% of nearly 4,000 patient records reviewed. Some 25 additional synonyms and 11 missing concepts were identified for addition to ICD-11. This was a welcome endorsement of the work that has gone into this project, to which so many people have contributed.


Why is ICD-11 important to dermatological care?

There have been enormous advances in the understanding of skin disease in the years since ICD-10 was adopted in 1990, which has meant that many of the block headings in the ICD-10 skin chapter lacked clarity, and that differences in the epidemiology, management and prognosis of disease could not be captured accurately in ICD-10. As outlined above, the new structure means that ICD-11 will enable coding of all clinical detail. ICD-11 will enable the development of special classifications allowing the collection of more information on less common diseases and less guesswork will be required for consistent coding. This, in addition to the potential for recording and analysis of health information, sharing health information between settings and data comparisons over different time periods, means that ICD-11 is a critical tool for dermatologists to support their efforts to ensure that all people around the world can attain the best possible skin health.


What’s next?

The ILDS is committed to supporting WHO in the implementation of ICD-11 going forwards, including its uptake by dermatologists, in order to facilitate better patient care, research and resource allocations for many years to come. We will be contacting ILDS Members with further details in due course but, in the meantime, you can read more about ICD-11 and access a version online here:  https://www.who.int/classifications/icd/en/


Robert Chalmers
Dr Robert Chalmers, ILDS Lead, ICD-11


We extend our thanks to Dr Robert Jakob, Team Leader, Classifications, Terminologies and Standards at the WHO and his team for their substantial efforts to bring the ICD-11 to fruition and their collaboration with the ILDS in this endeavour. Our sincere thanks also go to Dr Robert Chalmers, for his tireless and meticulous efforts on behalf of dermatologists and those living with skin diseases. Dr Chalmers has led the ILDS’ input into the dermatological components since 2008 and has been collaborating with many contributors over the last 10 years including Professor Michael Weichenthal who co-chaired the TAG, members of the TAG, ILDS member societies and dermatologists from around the world. Due to the efforts of this global community of skin experts, dermatology is now better represented in the classification of diseases than it has ever been.

[1] The decision-making body of the World Health Organization