Handling hierarchies using ancestors

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If your current terminology (ICD-10, Loinc, RxNorm, etc.) based on hierarchy attribute you may request to update this terminology

Ancestors

We've introduced new way of handling hierarchies in Aidbox two-phase terminology approach. Previously we used only Concept.hierarchy attribute but this approach had a few limitations: for complex ontology-like terminologies (such as SnomedCT) it didn't allow to support several value set filter operations such as child-of, generalizes, descendent-leaf.

Use of ancestors attribute is optional and we still support hierarchy attribute as well. For all terminologies provided since Aidbox July 2022 latest release ancestors attribute will be included by default instead of hierarchy attribute.

For example, source terminology structure looks as follows:

This is how ancestors hierarchy is supposed to be represented in Aidbox Concept resource:

Concepts

{"code": "code1"}
{"code": "code1.1",  "ancestors":  {"code1": 1}}
{"code": "code1.2",  "ancestors":  {"code1": 1}}
{"code": "code1.1.1", "ancestors": {"code1": 2, "code1.1": 1}}
{"code": "code1.2.1", "ancestors": {"code1": 2, "code1.1": 1, "code1.2": 1}}

Ancestors attribute is an object which stores all concept ancestors and number of hops between them, where key is an ancestor code and value is the number of hops.

How to use ancestors attribute for ValueSet declaration & expansion

If you want to declare ValueSet that based on concepts with ancestors attribute you should add "use-ancestors" resource meta tag.

resourceType: ValueSet
meta:
  tag:
  - code: use-ancestors
id: code1.1-descendents
url: http://example.org/code1.1-descendents
status: draft
compose:
  include:
  - system: http://example.org/CodeSystem
    filter:
    - property: code
      op: is-a
      value: 'code1.1'