ICD 11 – The Content Model, Part 1

ICD 11 book coverThe Content Model of an ICD entity in the 11th revision of the International Classification of Diseases and Related Health Problems (ICD) forms the basis of this succeeding post to the earlier post ICD 10 & ICD 11 Development – How, What, Why & When (this link will open in a new tab of your current window).

It is not my intention to write volumes on Content Model, rather I shall attempt to share the basics of this model in its simplest form that I have understood as compared to ICD 10.

We know that ICD 10  had evolved to include morbidity classification from its original design to record causes of death. We are aware that ICD is also used for reimbursement (in countries like in the US), and also used in specialty areas such as oncology and primary care.

Then we also know that from the ICD-10 tabular list found in Volume 1, ICD 10 is organised as a monohierarchy. Monohierarchy is a top-down classification. Perhaps the following example of a monohierarchy among Felidae, the biological family of the cats will make things clearer of what I wish to write  about how ICD 10 codes are organised.


ICD 10 uses letters for an initial broad categorisation (e.g., I for diseases of the circulatory system) and combined with digits (e.g. I00 to I02) for each successive level of child codes. Sibling codes (e.g. I01.0 and I01.1) are considered to be exhaustive and mutually exclusive, requiring the use of residual categories—“unspecified” and “other”—at each level, (e.g. I01.9 Acute rheumatic heart disease, unspecified).

A code may have associated inclusions (I10 Essential (primary) hypertension Incl: High blood pressure) and exclusions (e.g. I01.0, Excl: when not specified as rheumatic [I130.-]).

Inclusions are exemplary terms or phrases that are synonymous with the title of the code or terms representing more specific conditions (e.g. I21 Acute myocardial infarction Incl.:myocardial infarction specified as acute or with a stated duration of 4 weeks (28 days) or less from onset).

Most exclusions are either conditions that might be thought to be children of a given condition but, because they occur elsewhere in the classification, must be excluded from appearing under it (e.g. I25.2 for old myocardial infarction); others are codes representing possible co-occurring conditions that should be distinguished from the condition (e.g.I23 Certain current complications following acute myocardial infarction i.e to say co-occuring or concurrent with acute myocardial infarction (I21-I22).

As I have posted in the posts ICD 11 – history of the development of the ICD from 1853 to 2015 (this link will open in a new tab of your current window), ICD 11 is been developed as a participatory Web-based process.

The development of ICD-11 is aimed to create an information infrastructure and workflow processes that utilises knowledge from existing hierarchies of codes and titles found in ICD 10 Volume 1 as I have elaborated above, and supplementary volumes of rules (found in ICD 10 Volume 2) and indices (found in ICD 10 Volume 3).

This new ICD 11 information infrastructure captures the knowledge that underpins the definition of an ICD entity as we know of it today – again as I have elaborated above, which will thus aid the review of best scientific evidences to enable the definition of diseases and health conditions, encoding of the eotiology and the anatomical and physiological aspects of the disease, and mappings to other terminologies and ontologies.

Initially the workflow of the collaborative development of new content and proposed changes, review and approval processes, and the creation of draft classifications for field testing was undertaken by Topic Advisory Groups (TAGs) for various specialty areas.

The workflow continued with the Alpha Draft of ICD-11 revision process with comments and suggestions by interested parties collected in a social process on the Web and  ended by May 2010, and continued with the Beta Draft with field trials of draft standards.

The Alpha and Beta drafts have produced the new ICD 11 information infrastructure based on the Content Model for ICD 11 which represents ICD entities in a standard way, each ICD entity defined by “parameters” representing different dimensions – a parameter expressed using standard terminologies known as “value sets” that specifies the structure and details of the information that should be maintained for each ICD category in the revision process and which thus allows for computerisation.

In the next post, I shall post about the basic structure of the Content Model.


  1. International Statistical Classification of Diseases and Related Health Problems, The Tabular List Volume 1 Version 2010, 2010 edn, World Health Organisation, Geneva, Switzerland
  2. World Health Organisation, 2012, Content Model, viewed 18 March 2013, < http://www.who.int/classifications/icd/revision/contentmodel/en/index.html >

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