AllergyIntolerance | Medplum

AllergyIntolerance Resource

A record of a clinical assessment of an allergy or intolerance; a propensity, or a potential risk to an individual, to have an adverse reaction on future exposure to the specified substance, or class of substance.

Where a propensity is identified, to record information or evidence about a reaction event that is characterized by any harmful or undesirable physiological response that is specific to the individual and triggered by exposure of an individual to the identified 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.

Note for Reviewers

Presently open issues for this resource:

• This resource represents a condition of susceptibility to a substance, with a list of supporting events and/or symptoms, and has no direct relationship to an event reporting framework; this will be re-assessed when adverse event reporting resource(s) and/or profiles are added to FHIR.
• Other HL7 models and the openEHR archetype have "exposure date" but this is not found in any surveyed systems, so this is left as an extension (more appropriate for adverse event reporting).

This resource is used to provide a single place within the health record to document a range of clinical statements about adverse reactions to substances/products, including:

• record a clinical assessment of the individual's propensity to a potential future reaction upon re-exposure.
• record cumulative information about the reaction to each exposure, including 'no reaction' if appropriate.

Use to record information about the positive presence of the risk of an adverse reaction:

• to support direct clinical care of an individual.
• as part of a managed adverse reaction or allergy/intolerance list.
• to support exchange of information about the propensity and events related to adverse reactions.
• to inform adverse reaction reporting.
• to assist computerized knowledge-based activities such as clinical decision support and alerts.

Use to record information about adverse reactions to a broad range of substances, including: biological & blood products; incipients and excipients in medicinal preparations; foods; metal salts; and organic chemical compounds.

Adverse reactions may be:

• an allergy (typically type I hypersensitivity, plus other "allergy-like" reactions, including pseudoallergy).
• an intolerance (typically non-immune adverse reactions that are not determined or perceived to be allergic or "allergy-like", and are to some degree idiosyncratic and/or individually specific [i.e. are not a reaction that is expected to occur with most or all patients given similar circumstances]).

In clinical practice distinguishing between allergy and intolerance is difficult and might not be practical. Often the term "allergy" is used rather generically and may overlap with "intolerance", and the boundaries between these concepts might not be well-defined or understood. As noted above, the term "intolerance" should generally be applied to a propensity for adverse reactions which is either determined (to the extent that is possible) or perceived to not be allergic or "allergy-like". If it is not possible to determine whether a particular propensity condition is an allergy or an intolerance, then the type element should be omitted from the resource. Identification of the type of reaction is not a proxy for seriousness or risk of harm to the patient, which is better expressed in the documentation of the clinical manifestation and the assessment of criticality.

The sensitivity in the case of either an allergy or intolerance is unique to the individual, and is distinguished from those reactions that are a property of the circumstance, such as toxicity of a food or drug, overdose, drug-drug, drug-food, or drug-disease interaction (which are reactions that would be expected to occur for any individual given the same circumstances).

The risk of an adverse reaction event or manifestation should not be recorded without identifying a proposed causative substance (including pharmaceutical products) or class of substance. If there is uncertainty that a specific substance is the cause, this uncertainty can be recorded using the 'verificationStatus' data element. If there are multiple possible substances that may have caused a reaction/manifestation, each substance should be recorded using a separate instance of this resource with the 'verificationStatus' set to an initial state of 'unconfirmed' so that adverse reaction checking can be supported in clinical systems. If a substance, agent or class is later proven not to be the cause for a given reaction then the 'verificationStatus' can be modified to 'refuted'.

This resource has been designed to allow recording of information about a specific substance (e.g., amoxicillin, oysters, or bee sting venom) or pharmaceutical product or, alternatively, a class of substance (e.g., penicillins). If a class of substance is recorded, then identification of the exact substance can be recorded on a per exposure basis.

The scope of this FHIR resource has deliberately focused on identifying a pragmatic data set that is used in most clinical systems or will be suitable for most common clinical scenarios; extensions can be used to add additional detail if required. Examples of clinical situations where the extension may be required include: a detailed allergist/immunologist assessment, for reporting to regulatory bodies or use in a clinical trial.

The act of recording any adverse reaction in a health record involves the clinical assessment that a potential hazard exists for an individual if they are exposed to the same substance/product/class in the future - that is, a relative contraindication - and, in the absence of additional information indicating a higher level of potential risk, the default 'criticality' value should be set to 'Low Risk'. If a clinician considers that it is not safe for the individual to be deliberately re-exposed to the substance/product again, for example, following a manifestation of a life-threatening anaphylaxis, then the 'criticality' data element should be amended to 'High Risk'.

AllergyIntolerance and RiskAssessment

AllergyIntolerance describes a specific type of risk - propensity to reaction to a substance/product while RiskAssessment describes general risks to a subject, not generally based on a reaction.

AllergyIntolerance and Immunization.reaction

Immunization.reaction may be an indication of an allergy or intolerance. If this is deemed to be the case, a separate AllergyIntolerance record should be created to indicate it, as most systems will not query against past immunization.reactions.