Patient Allergy or Intolerance Data Absent Reason
Context and value of a Data Absent Reason (DAR) indicating why information is missing or not recorded about some or all of a patient's allergies or intolerances.
When a DAR is specified, this class shall be populated, but Patient Allergy or Intolerance shall not.
Conversely, when an actual allergy or intolerance is specified, the Patient Allergy or Intolerance class shall be populated, but this class shall not.
In this class, the DAR Code, i.e., the attribute Allergy or Intolerance Data Absent Reason Code, must always be populated.
If the DAR applies to all of a patient's allergies and intolerances (for example, the patient declined to answer the question “Do you have any allergies or intolerances?”), then only the DAR Code is populated. All other attributes must be left empty.
If the DAR applies to a specific allergy or intolerance (for example, if the patient declined to answer the question "Are you allergic to Penicillin-G?"), then the DAR Code records the reason (e.g., asked-declined) and the context attribute Allergy or Intolerance Code identifies the specific allergen (e.g., Penicillin-G).
If the DAR applies to a specific category of allergies or intolerances (e.g., if the patient declined to answer the question "Do you have any food allergies or intolerances?"), then the DAR Code records the reason (e.g., asked-declined) and the context attribute Allergy or Intolerance Category Code identifies the specific category (e.g., food).
If the DAR applies to all allergies or to all intolerances, but not to both (e.g., if the patient declined to answer the question "Do you have any allergies?"), then the DAR Code records the reason (e.g., asked-declined) and the context attribute Allergy or Intolerance Type Code identifies whether the DAR applies to allergies or to intolerances (e.g., allergies).
Those context attributes - Allergy or Intolerance Code, Allergy or Intolerance Category Code, Allergy or Intolerance Type Code - can also be used in combination (for example, if the patient declined to answer the question "Do you have any food allergies?").
However, it is redundant to specify both Allergy or Intolerance Code and Allergy or Intolerance Category Code, since a code belongs to a unique category.
Appears in
Constraints
Unique key(s)
- Patient, Allergy or Intolerance Code if specified, Allergy or Intolerance Type Code if specified, Allergy or Intolerance Category Code if specified
Stereotype(s)
n/a
Attributes
| Attribute | Type | Multiplicity | Attribute note |
|---|---|---|---|
| Allergy or Intolerance Code | Codeable Concept | 0..1 | Uniquely specifies the pharmaceutical or biological product or substance (e.g., peanut) to which the person has an allergy or intolerance.
Value Set: https://fhir.infoway-inforoute.ca/ValueSet/pharmaceuticalbiologicproductandsubstancecode |
| Allergy or Intolerance Type Code | Codeable Concept | 0..1 | Uniquely specifies the underlying physiological mechanism for the reaction risk, i.e., allergy or intolerance.
Value Set: https://fhir.infoway-inforoute.ca/ValueSet/allergyintolerancetype |
| Allergy or Intolerance Category Code | Codeable Concept | 0..1 | Uniquely specifies the classification of the pharmaceutical, biological product or substance (e.g., food, medication, environment) to which the person has the allergy or intolerance.
Value Set: https://fhir.infoway-inforoute.ca/ValueSet/allergyintolerancecategory |
| Allergy or Intolerance Data Absent Reason Code | Codeable Concept | 1 | Uniquely specifies the reason that allergy or intolerance information is missing or not recorded for a patient (e.g., asked-declined, not-asked, unknown).
Value Set: http://terminology.hl7.org/CodeSystem/data-absent-reason |
Relationships
| From class | From multiplicity | Relationship | To class | To multiplicity |
|---|---|---|---|---|
| Patient Allergy or Intolerance Data Absent Reason | 0..* | has | Clinical Information Life Cycle Event | 0..* |
| Patient Allergy or Intolerance Data Absent Reason | 0..* | documented in | Encounter | 0..1 |
| Patient Allergy or Intolerance Data Absent Reason | 0..* | for | Patient | 1 |
Contact us
If you have questions about this initiative, would like to be added to our stakeholder notification list or would like to participate in our consultations, please email us.
How to cite:
Canadian Institute for Health Information. Patient Allergy or Intolerance Data Absent Reason. Accessed November 02, 2026.
