ConditionDefinition — Disease catalogue
ConditionDefinition describes a disease as a universal concept, distinct from Condition which is the instance "this patient has this disease".
Purpose
ConditionDefinition is a new R5 member of the "Definition" pattern (ActivityDefinition, PlanDefinition, MedicationKnowledge). It carries the abstract description of a disease: possible severity, related observations, recommended follow-up questionnaires, standard treatment plans.
A patient-instance Condition can reference a ConditionDefinition via basedOn
or extension to benefit from catalogue-level rules.
Key fields
| Field | Type | Cardinality | Role |
|---|---|---|---|
url | uri | 0..1 | Canonical URL of the definition. |
version | string | 0..1 | Editorial version. |
name / title | string | 0..1 | Internal name / human title. |
status | code | 1..1 | draft, active, retired, unknown. |
code | CodeableConcept | 1..1 | Clinical code (SNOMED CT, ICD-10). |
severity | CodeableConcept | 0..1 | Default severity. |
bodySite | CodeableConcept[] | 0..* | Typical anatomical sites. |
stage | CodeableConcept[] | 0..* | Clinical stages. |
observation / medication / questionnaire / plan | BackboneElement[] | 0..* | Resources linked to the catalogue. |
JSON example
Type 2 Diabetes catalogue:
{
"resourceType": "ConditionDefinition",
"id": "diabetes-type2",
"url": "http://example.org/fhir/ConditionDefinition/diabetes-type2",
"version": "2026.1",
"name": "DiabetesType2",
"title": "Diabetes mellitus type 2",
"status": "active",
"experimental": false,
"code": {
"coding": [{
"system": "http://snomed.info/sct",
"code": "44054006",
"display": "Diabetes mellitus type 2"
}]
},
"severity": {
"coding": [{ "system": "http://snomed.info/sct", "code": "24484000", "display": "Severe" }]
}
}Common pitfalls
- ConditionDefinition / Condition confusion: the definition describes the disease in general. Condition is the patient instance.
- ConditionDefinition without canonical
url: cross-server reference unresolvable. - Draft maturity level: structure may evolve in R6, do not commit strongly to detail.
Related resources
- Condition — clinical instance.
- ActivityDefinition, PlanDefinition — other definitions.
- ObservationDefinition — catalogue of associated observations.
- MedicationKnowledge — catalogue of associated drugs.
See also: Condition, PlanDefinition.