• Approved by the World Health Assembly in 1989
• Tabular List published in 1992; Index published in 1994
• Evaluation of ICD-10 for U.S. purposes 1994-1997
• Implemented in the US for mortality in 1999 (death statistics)
• NCVHS Hearings 1997-2003 (National Committee on Vital and Health Statistics)
• NPRM 2008 (Notice of Proposed RuleMaking)
• Final Rule 2009 for ICD-10-CM
• Final Rule 2012 for ICD-10-CM
• Interim Final Rule 2014 for ICD-10-CM
• ICD-10-CM Implementation October 1, 2015
• ICD-10 is currently translated into 43 languages and used in over 100 countries with more than 2 dozen modifications (such as the United State's ICD-10-CM)
• ICD-10 is now >25 years old

Update needed to...

• Capture advances in health science and medical practice
• Better address multiple topics; e.g. quality & safety, traditional medicine, etc.
• Address persistent major gaps in basic use for mortality statistics
• Improve morbidity statistics
• Improve integration of other classifications and terminologies

Coding problems to be solved with ICD-11 (examples)

• Antimicrobial resistance - essentially missing in ICD-10
• HIV subdivisions - outdated detail in ICD-10
• Simplified Diabetes coding
• Skin cancer - melanoma types missing – basalioma missing in ICD-10
• Valve diseases - outdated structure, need by valve, less rheumatic
• Postprocedural conditions - clarify when use 19 and when not for postprocedural
• Cancers with histopathology – ICD-O for cancer registries embedded
• External causes – better coding traffic accidents

ICD-11 Revision Goals

• Multi-purpose and coherent classification
  • Mortality, morbidity, primary care, clinical care, research, public health, etc.
  • Consistency and interoperability across different uses
  • International multilingual reference standard for scientific comparability (Arabic, Chinese, English, French, Russian, Spanish)
• Ensure that ICD-11 will function in an electronic environment
  • Digital product
  • Link with terminologies (e.g., SNOMED) and other classifications
  • Support electronic health records and information systems

• Category increases to 4 digits, ex. Alzheimer disease: G30 => 8A20 - complete range: 1A00.00 to ZZ9Z.ZZ
• First digit of the code always relates to the chapter number: 1 - Z. All codes in the chapter always have the same character in the first position. 1A00 is a code in Chapter 1, and BA00 is a code in Chapter 11.
• Codes always have a letter in the second position to distinguish from the codes of ICD-10
• Letters "O" and "I" are NOT used - 1/l is always the number 1, 0/o is always a zero, "L" is used but only in upper-case (all code letters should be shown in upper-case)
• Chapters are numbered with Arabic numerals (0-9) instead of Roman (I, II, III, etc.) - a change from WHO's ICD-10; US's ICD-10-CM had already changed to Arabic
• The terminal letter 'Y' is reserved for the residual category 'other specified' and the terminal letter 'Z' is reserved for the residual category 'unspecified'. ICD-10 usually used an '8' or '9' to indicate 'other' and 'unspecified, respectively. Note: ICD-11 X (Extension) codes may end with an Y or a Z but those characters DO NOT represent the 'other' and 'unspecified' concepts.
• In order to describe a causal relationship between conditions in a code title the preferred term is 'due to'.
• In order to indicate the concurrence of two conditions in a code title the preferred term is 'associated with'.
• Some diseases have changed location – e.g., Cerebrovascular diseases moved from circulatory to nervous system chapter
• 6 new chapters
  • Diseases of blood and blood forming organs
  • Disorders of the immune system
  • Conditions related to sexual health
  • Sleep-wake disorders
  • Traditional medicine
  • Extension codes
• Extension codes - start with 'X' (see below)
• Cluster coding (see below)

Extension codes are 4-6 digit codes that always start with 'X'. They are comprised of groups of codes e.g. anatomy, agent, histopathology and other aspects that may be used to add detail to a Stem Code. ('Stem Codes' are codes that are not Extension codes.) Extension codes are not to be used alone but must be added to a Stem Code. Not all Extension codes can be used with every Stem Code.

• Severity Scale value
• Temporality
• Aetiology (Causality, Infections Agents)
• Topology Scale Value
• Anatomy and topography
• Histopathology
• Dimensions of injury
• Dimensions of external causes
• Consciousness
• Substances
• Diagnosis code descriptors
• Capacity or context
• Health Devices, Equipment and Supplies

Example:
  Severity Scale value
    Mild Moderate Severe Scale Value
      XS8H None
      XS5W Mild
      XS0T Moderate
      XS25 Severe
      XS2R Profound
      XS4X Unspecified severity

'Code also' instructions provide additional aetiological information which is mandatory to code in conjunction with certain categories, because that additional information is relevant for primary tabulation. The 'code also' instruction marks the categories that must be used in conjunction with the indicated condition. In some instances, they may be a reason for treatment in their own right, where aetiology is unknown.

ICD–11 has an explicit way of marking codes that are postcoordinated to describe one condition, called cluster coding. This is a notable new feature in ICD-11 that creates an ability to link core diagnostic concepts (i.e. stem code concepts) when desired, and/or to add clinical concepts captured in Extension codes to primary stem code concepts.

Cluster coding uses either forward slash (/) or ampersand (&) to show more than one code used together to describe a documented clinical concept.

Codes that are not Extension codes are referred to as 'Stem Codes'. The format of the code cluster is: 

Stem Code[&Extension][...][/Stem Code[&Extension][...]...]

Example:  DD51 & XK8G / ME24.2 & XT5R

A Stem Code may have zero or more Extensions concatenated. Each concatenation is preceded with an ampersand character (&).

Additional Stem Codes may be concatenated to the preceding Stem Code or Stem Code's final Extension. Each of these concatenations is preceded with a forward slash character (/).

(For readability, spaces are added to the code clusters shown here. Spaces should not be included for data storage or transmittal.)

Example 1:  BA41.0 & XA7RE3 & XA7NQ7
  format:  Stem Code & Extension & Extension
  BA41.0 - Acute ST elevation myocardial infarction
    XA7RE3 - Anterior wall of heart
    XA7NQ7 - Left anterior descending coronary artery

Example 2:  GB51 & XK8G & XN6P4
  format:  Stem Code & Extension & Extension
  GB51 Acute pyelonephritis
    XK8G - Left
    XN6P4 - Escherichia coli

Example 3:  8A20 / 6D80.0 & XS0T
  format:  Stem Code / Stem Code & Extension
  8A20 - Alzheimer disease
    Has manifestation of:  6D80.0 - Dementia due to Alzheimer disease with early onset
     Has severity of:  XS0T - Moderate

Example 4:  DD51 & XK8G / ME24.2 & XT5R
  format:  Stem Code & Extension / Stem Code & Extension
  DD51 - Inguinal hernia
    XK8G - Left
    Associated with:  ME24.2 - Digestive system obstruction
      XT5R - Acute

Example 5:  pedestrian fall injury - concussion and open fracture shaft of left ulna due to fall on uneven sidewalk while taking a walk:

Condition (code) 1:  NA07.0 - Concussion
/ Has causing condition (code also):  PA60 - Unintentional fall on the same level or from less than 1 metre
& Object or substance producing injury:  XE1DA - Uneven surface, not elsewhere classified
& Place of occurrence:  XE53A - Sidewalk
& Activity when injured:  XE617 - Leisure or play
= Code Cluster:  NA07.0 / PA60 & XE1DA & XE53A & XE617

Condition (code) 2:  NC32.2 - Fracture of shaft of ulna
& Laterality:  XK8G - Left
& Fracture open or closed:  XJ7YM - Open fracture
/ Associated with:  PA60 - Unintentional fall on the same level or from less than 1 metre
& Object or substance producing injury:  XE1DA - Uneven surface, not elsewhere classified
& Place of occurrence:  XE53A - Sidewalk
& Activity when injured:  XE617 - Leisure or play
= Code Cluster:  NC32.2 & XK8G & XJ7YM / PA60 & XE1DA & XE53A & XE617

• Update on ICD-11: The WHO Launch and Implications for U.S. Implementation - September 12, 2018
• WHO's ICD-11 Reference Guide
• Overview of the ICD-11 for Mental Health
• Innovations and changes in the ICD-11 classification of mental, behavioural and neurodevelopmental disorders - January 2, 2019
• WHO releases new International Classification of Diseases (ICD 11) - June 18, 2018