Risk of harmful or undesirable, physiological response which is unique to an individual and associated with exposure to a substance.

To record a clinical assessment of a propensity, or potential risk to an individual, of an adverse reaction upon future exposure to the specified substance, or class of substance.

Substances include, but are not limited to: a therapeutic substance administered correctly at an appropriate dosage for the individual; food; material derived from plants or animals; or venom from insect stings.

This records identifiers associated with this allergy/intolerance concern that are defined by business processes and/or used to refer to it when a direct URL reference to the resource itself is not appropriate (e.g. in CDA documents, or in written / printed documentation).

Record of the date and/or time of the onset of the Allergy or Intolerance.

Date when the sensitivity was recorded.

Individual who recorded the record and takes responsibility for its conten.

The patient who has the allergy or intolerance.

The source of the information about the allergy that is recorded.

The recorder takes repsonsibility for the content, but can reference the source from where they got it.

Identification of a substance, or a class of substances, that is considered to be responsible for the adverse reaction risk.

It is strongly recommended that the substance be coded with a terminology, where possible. For example, some terminologies used include RxNorm, SNOMED CT, DM+D, NDFRT, ICD-9, IDC-10, UNI, ATC and CPT. Plain text should only be used if there is no appropriate terminology available. Additional details about a substance can be specified in the text.

Assertion about certainty associated with the propensity, or potential risk, of a reaction to the identified Substance.

Decision support would typically raise alerts for 'Unconfirmed', 'Confirmed', and 'Resolved' and ignore a 'Refuted' reaction. In particular, 'Refuted' may be useful for reconciliation of the Adverse Reaction List. Some implementations may choose to make this field mandatory.

Estimate of the potential clinical harm, or seriousness, of the reaction to the identified Substance.

The default criticality value for any propensity to an adverse reaction should be 'Low Risk', indicating at the very least a relative contraindication to deliberate or voluntary exposure to the Substance. 'High Risk' is flagged if the clinician has identified a propensity for a more serious or potentially life-threatening reaction, such as anaphylaxis, and implies an absolute contraindication to deliberate or voluntary exposure to the substance. If this element is missing, the criticality is unknown (though it may be known elsewhere).

Identification of the underlying physiological mechanism for the reaction risk.

Allergic (typically immune-mediated) reactions have been traditionally regarded as an indicator for potential escalation to significant future risk. Contemporary knowledge suggests that some reactions previously thought to be immune-mediated are, in fact, non-immune, but in some cases can still pose a life threatening risk. It is acknowledged that many clinicians may not be in a position to distinguish the mechanism of a particular reaction. Often the term "allergy" is used rather generically and may overlap with the use of "intolerance" - in practice the boundaries between these two concepts may not be well-defined or understood. This data element is included nevertheless, because many legacy systems have captured this attribute. Immunologic testing may provide supporting evidence for the basis of the reaction and the causative substance, but no tests are 100% sensitive or specific for sensitivity to a particular substance. If, as is commonly the case, it is unclear whether the reaction is due to an allergy or an intolerance, then the type element should be omitted from the resource.

Category of the identified Substance.

This data element has been included because it is currently being captured in some clinical systems. This data can be derived from the Substance where coding systems are used, and is effectively redundant in that situation.

Represents the date and/or time of the last known occurrence of a reaction event.

This date may be replicated by one of the Onset of Reaction dates. Where a textual representation of the date of last occurrence is required e.g. 'In Childhood, '10 years ago' the Comment element should be used.

Additional narrative about the propensity for the Adverse Reaction, not captured in other fields.

For example: including reason for flagging a seriousness of 'High Risk'; and instructions related to future exposure or administration of the Substance, such as administration within an Intensive Care Unit or under corticosteroid cover. The notes should be related to an allergy or intolerance as a condition in general and not related to any particular episode of it. For episode notes and descriptions, use AllergyIntolerance.event.description and AllergyIntolerance.event.notes.

Details about each adverse reaction event linked to exposure to the identified Substance.

Identification of the specific substance considered to be responsible for the Adverse Reaction event. Note: the substance for a specific reaction may be different to the substance identified as the cause of the risk, but must be consistent with it. For instance, it may be a more specific substance (e.g. a brand medication) or a composite substance that includes the identified substance. It must be clinically safe to only process the AllergyIntolerance.substance and ignore the AllergyIntolerance.event.substance.

Coding of the specific substance with a terminology capable of triggering decision support should be used wherever possible. The substance field allows for the use of a specific substance or a group or class of substances, for example "Penicillins". The specific substance field could be used for Amoxycillin. Duplication is acceptable when a specific substance has been recorded in the 'substance' field.

Statement about the degree of clinical certainty that the specific substance was the cause of the manifestation in this reaction event.

Clinical symptoms and/or signs that are observed or associated with the adverse reaction event.

Manifestation can be expressed as a single word, phrase or brief description. For example: nausea, rash or no reaction. It is preferable that manifestation should be coded with a terminology, where possible. The values entered here may be used to display on an application screen as part of a list of adverse reactions, as recommended in the UK NHS CUI guidelines. Terminologies commonly used include, but are not limited to, SNOMED CT or ICD10.

Text description about the reaction as a whole, including details of the manifestation if required.

Use the description to provide any details of a particular event of the occurred reaction such as circumstances, reaction specifics, what happened before/after. Information, related to the event, but not describing a particular care should be captured in the comment field. For example: at the age of four, the patient was given penicillin for strep throat and subsequently developed severe hives.

Record of the date and/or time of the onset of the Reaction.

Clinical assessment of the severity of the reaction event as a whole, potentially considering multiple different manifestations.

It is acknowledged that this assessment is very subjective. There may be some some specific practice domains where objective scales have been applied. Objective scales can be included in this model as extensions.

Identification of the route by which the subject was exposed to the substance.

Coding of the route of exposure with a terminology should be used wherever possible.

Additional text about the adverse reaction event not captured in other fields.

Use this field to record information indirectly related to a particular event and not captured in the description. For example: Clinical records are no longer available, recorded based on information provided to the patient by her mother and her mother is deceased.