FHIR Terminology Ecosystem IG, published by HL7 FHIR Product Director. This guide is not an authorized publication; it is the continuous build for version 1.9.6 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-tx-ecosystem-ig/ and changes regularly. See the Directory of published versions

Using ICF with HL7 Standards

Note: This page is temporarily here until it migrates to terminology.hl7.org

Using old versions of ICF with FHIR

The International Classification of Functioning, Disability and Health (ICF) is published by the World Health Organization. It classifies health and health-related domains - what a person's body does, its structures, what the person does, and the environment they do it in - and is the WHO framework for measuring health and disability.

ICF is now also published as a linearization of ICD-11 (http://id.who.int/icd/release/11/icf, see Using ICD-11 with FHIR). This page is about the older, standalone releases of ICF - the 2001 classification and its annual updates - which use the familiar alphanumeric codes such as b1100 and s7300, and are still widely used. Two of them are available as CodeSystems in the fhir.tx.support package: 2001a and 2017a.

Summary

License

ICF is published by WHO, and the same rules apply to licensing ICF as to licensing ICD. See http://icd.who.int/ and WHO's ICF pages.

Note: implementers should check WHO's current terms before using ICF.

ICF Codes

ICF has four components, and the first letter of every code says which one it belongs to:

The letter is followed by the chapter number, then the second level (two more digits), then the third and fourth levels (one digit each): b1 Mental functions, b110 Consciousness functions, b1100 State of consciousness. Every code also sits under its component in the hierarchy.

The code system also contains the components themselves (b, s, d, e), the chapters (b1) and the blocks (b110-b139). These are headings: they are marked notSelectable, and cannot be used to code with. In 2001a the components are themselves under a root concept ICF.

{
  "system" : "http://hl7.org/fhir/sid/icf",
  "version" : "2001a",
  "code" : "b1100",
  "display" : "State of consciousness"
}

Qualifiers

In ICF itself, a code is not complete until it is qualified: the category says what is being described, and qualifiers say how much of a problem there is, and of what kind. Qualifiers follow the category code after a ., one digit each, and what each position means depends on the component the code belongs to:

So s7300.183 is Structure of upper arm, with a mild impairment (1), the nature not specified (8), on both sides (3); and d450.12 is Walking, with a mild performance problem (1) and a moderate capacity problem (2).

In the FHIR ecosystem, though, an unqualified code has uses of its own, and the code system accepts one as a valid code:

• value sets, concept maps and profiles name categories - which areas of functioning a form or a measure is about - rather than findings about a person
• the qualifier may be recorded somewhere other than the code: an Observation whose code is the category and whose value is the rating, or a questionnaire item asking about the category
• the hierarchy, $lookup and $subsumes work on categories

A record of a finding about a person should carry its qualifiers, and a value set can require them - see Filter Properties.

The rules are:

• the qualifiers are positional, and a code may have as many as its component allows (above): one for b, up to three for s, and up to four for d - performance and capacity, then optionally capacity with assistance and performance without assistance. b1100.21 and d450.12345 are not valid
• a position cannot be skipped. 8 (not specified) is what fills a position that has nothing to say: to give a localization without a nature, write s7300.183, not s7300.1 3
• each digit must be one of the values of its position's scale (below): b1100.5 is not valid, since the extent has no 5, and nor is d450.15
• only a selectable category can be qualified - not a component, chapter or block (b1.2 and b110-b139.2 are not valid)
• qualifiers are not required by the code system: b1100 on its own is a valid code. Some uses of ICF do require them, and a value set can say so - see Filter Properties

A qualified code is a code in its own right: Coding.code is the whole thing.

{
  "system" : "http://hl7.org/fhir/sid/icf",
  "version" : "2001a",
  "code" : "s7300.183",
  "display" : "Structure of upper arm: MILD impairment, both sides"
}

The values of each scale are concepts in the code system, so they can be looked up and their definitions read. Each scale has a heading concept (q1 to q4), and its values are q1-0, q1-1 and so on. These are not codes to use on their own: they have a kind property that says which scale they belong to (extent, nature, localization or problem), where every ordinary ICF code has the kind primary.

Extent of impairment (q1)

Nature of the change in the respective body structure (q2)

Localization (q3)

Extent of problem (q4)

Environmental factors. In ICF, an environmental factor (e) has one qualifier, which says whether the factor is a barrier or a facilitator, and how much of one: a barrier is written with . (e310.2, a moderate barrier), and a facilitator with + in place of the . (e310+3, a substantial facilitator). There are open questions about the facilitator scale, and qualifiers on environmental factors are not supported yet: e310 is a valid code, but e310.2 and e310+3 are not. Expect this to change.

Versions

Two releases are available:

• 2001a - the 2001 classification. It carries translations - see Display Terms
• 2017a - the classification with the updates to 2017. English only

The version is needed (versionNeeded is true): a code may mean something different, or not exist, in a different release, so a Coding should say which release it is from. The qualifier scales are the same in both releases.

ICF in ICD-11 is a different code system, with different codes (http://id.who.int/icd/release/11/icf, versioned by ICD-11 release), and is not a version of this one.

Display Terms

The display of a code is the category's title. In 2001a, translations are available in French (fr), Spanish (es), Russian (ru), Chinese (zh) and Turkish (tr), and displayLanguage (or the HTTP Accept-Language) selects one. 2017a has English only.

The display of a qualified code is generated: the category's title, a :, then the meaning of each qualifier, separated by , . The qualifiers of a d code are each introduced by what they are - performance, capacity, and so on - since they share one scale. A qualifier of 8 (not specified) says nothing, so it is left out - and if every qualifier is 8, the display is just the category's title:

The category's own title is not a valid display for a qualified code (unless every qualifier is 8): $validate-code of s7300.183 with the display Structure of upper arm reports the wrong display.

Properties

These are the properties a $lookup may return:

A qualified code has its category's properties as well, other than parent. A qualifier that is 8 is still reported: s7300.183 has nature q2-8.

Filter Properties

The qualifier filters combine with the others in an include, so a value set can say which codes, and which qualifiers. For example, body structures, which must have all three qualifiers:

"compose" : {
  "include" : [{
    "system" : "http://hl7.org/fhir/sid/icf",
    "version" : "2001a",
    "filter" : [
      { "property" : "concept", "op" : "is-a", "value" : "s" },
      { "property" : "extent", "op" : "exists", "value" : "true" },
      { "property" : "nature", "op" : "exists", "value" : "true" },
      { "property" : "localization", "op" : "exists", "value" : "true" }
    ]
  }]
}

s7300.123 is in this value set; s7300.12 (no localization), s7300.128 and s7300.183 (an 8) and s7300 are not.

Or activities and participation, which must have a capacity qualifier - d450.12 is in it, and d450.1 and d450.18 are not:

"compose" : {
  "include" : [{
    "system" : "http://hl7.org/fhir/sid/icf",
    "version" : "2001a",
    "filter" : [
      { "property" : "concept", "op" : "is-a", "value" : "d" },
      { "property" : "capacity", "op" : "exists", "value" : "true" }
    ]
  }]
}

And all of ICF, with no qualified codes:

"compose" : {
  "include" : [{
    "system" : "http://hl7.org/fhir/sid/icf",
    "version" : "2001a",
    "filter" : [{ "property" : "qualified", "op" : "=", "value" : "false" }]
  }]
}

A value set that lists codes contains only the codes it lists: if it lists b1100.2, it does not contain b1100.3 - or b1100 - and if it lists s7300.888, it does not contain s7300.88, even though the two say the same thing.

Expansions. Qualified codes can be listed in a value set, and are expanded with their generated displays. But they cannot be enumerated: an include that admits qualified codes - any include without qualified = false - expands to the plain codes it contains, and the expansion is marked as incomplete (valueset-unclosed), since the qualified codes are not in it.

Implicit Value Sets

No implicit value sets have been defined for ICF.