• Appendix A: Glossary of Terms

• Appendix B: Historical SNOMED CT content perspective

• Appendix C: Analysis of the HL7 C-CDA model

• Appendix D: Analysis of the HL7 Patient Care Domain Analysis Model

The following table contains the definition of any terms used within this document.

Hierarchy of terms:

Term List:

1. Joint Task Force on Practice Parameters; American Academy of Allergy, Asthma and Immunology; American College of Allergy, Asthma and Immunology; Joint Council of Allergy, Asthma and Immunology. Drug allergy: an updated practice parameter. Ann Allergy Asthma Immunol. 2010 Oct; 105(4):259-273. doi: 10.1016/j.anai.2010.08.002.

2. Thanai Pongdee. Food Allergy Versus Food Intolerance. Published by American Academy of Allergy Asthma & Immunology 02/2011.

Efforts to revise the allergy-related hierarchies in SNOMED can be traced back to at least 2005 during which time several deficiencies were identified in the modeling of allergies and adverse reactions involving the inconsistent use of the causative agent role and the need to clearly differentiate the propensity to react from the reaction itself in order to better integrate with proposed HL7® models for allergy. Thus, allergy (disorder) was replaced by allergic state (disorder) as a child of 420134006 | Propensity to adverse reactions (disorder)| and adverse reactions/allergy to various substances, food and drugs were updated in the 2006 release of SNOMED CT. Additional revisions to the SNOMED CT allergy content occurred in 2006 included an attempt to align the terminology with the nomenclature for allergy developed by the WAO/EAAACI in 2001.

Another update to the allergy terminology was implemented for the July 2013 release of SNOMED CT. This update organized all of the three main allergy classes (conditions, propensities and reactions) which up to this point resided in three unrelated hierarchies under a single “allergy condition” hierarchy. Additionally, the July 2013 release included a more robust concept model for hypersensitivity/allergy conditions, particularly for the allergy propensity class (since named allergic disposition). Text definitions for the major organizing classes were also included for the first time.

Revising SNOMED CT to the three classes model meant that hypersensitivity data were represented by:

• Abnormal structures, which are diseases that may have a finding site and a morphology e.g. allergic rhinitis

• Dispositions (propensities), which model the patient state of an “Allergy to x”. <<420134006 |Propensity to adverse reactions(finding)|

• Processes (reactions) Example: “Allergic reaction to x”. <<281647001 |adverse reaction (disorder)|

• Conditions, which represent disorders characterized by abnormal structures, propensities that may be realized as pathologic processes (i.e. reactions) or the reactions themselves.

  • Example

    • 473011001 |Allergic condition (finding)|

Several models were discussed for representing the Allergy information. Especially because there was set a requirement that the information should express the difference between an allergy and intolerance, which have clinically very different meanings. Should be build a model on our own or did a standard models exist which matched our use case? The Semantic team was considering adoption the HL7® CDA/CCD model for allergies where "adverse event type" is used with a terminology such as SNOMED high-level classification, so that the distinction between allergies versus intolerances can be managed. The whole model was not adopted, but a simplified version of it due the fact it contained too many dimensions, which were out of scope for the PS use case.

The distinction between reactions to substances/food versus drugs was also a request and thereby explicit handled, with appropriate value sets.

SNOMED CT was selected for three attributes in the proposed Allergy model:

Reaction Allergy:

The Value Set was selected to code the clinical manifestations of allergy developed by patient in the "Allergies and Other Adverse Reactions" section of the patient Summary (along with epSOSActiveIngredient). This value set was inherited as defined in CDA/CCD Allergy Model, since the choice of the Allergy model was taken.

AdverseEventType:

The value set was selected to cods the patient's kind of adverse reactions against substance, food or drugs. This value set was inherited as defined in CDA/CCD Allergy Model, since the choice of the Allergy model was taken.

Allergen No drugs:

The Value Set was created to code the allergenic agents (apart from drugs) against which the patient has developed an adverse reaction due to the fact that this type of information was not part of the CDA/CCD Allergy Model. The value set was created in a 5-step workflow (created, review by clinician, reviewed by semantic team, revised by clinician, reviewed and approved by Semantic Team). Relevant sub-hierarchies in SNOMED CT were selected and some single terms. The value set was validated by the Semantic Team for acceptance as a minimum value set/data set.

epSOSReactionAllergy

2.16.840.1.113883.6.96

If referred to the type (e.g. not allergic intolerance)

epSOSAdverseEventType

2.16.840.1.113883.6.96

WHO ATC

2.16.840.1.113883.6.73

If not:

epSOSAllergennoDrugs

2.16.840.1.113883.6.96

The Federal Health Information Model is a project under a larger program called Federal Health Interoperability Modeling and Standards (FHIMS), which is an initiative of the Federal Health Architecture (FHA). Briefly, the United States federal government has established a Federal Enterprise Architecture (FEA), which provides guidance to federal agencies on how they should develop their enterprise architectures. The methodology used by FEA, the Federal Segment Architecture Methodology (FSAM) recognizes that some "lines of businesses" in which the federal government is engaged cross agency boundaries. The healthcare line of business is one such case. As a result, the FHA was established as a partnership of over 20 departments and agencies to coordinate Healthcare Information Technology (sometimes called Healthcare IT, or HIT) activities among those partners. The FHA is managed by the Office of the National Coordinator for Health IT (ONC). The FHA has served as a forum by which the partner agencies have collaborated on several important initiatives, including the Nationwide Health Information Network.

The FHIMS program is intended to coordinate the efforts of the partner agencies with respect to information and terminology standards, including the coordination of agency efforts at relevant Standards Development Organizations (SDOs) such as Health Level Seven (HL7®), the National Council for Prescription Drug Programs (NCPDP), Integrating the Healthcare Enterprise (IHE), and others.

Another FHIMS initiative is the Federal Health Terminology Model project, which coordinates partner agency efforts to develop healthcare terminology models, and to enumerate "value sets" that can be associated with the Information Model. The Terminology Model is closely related to the Information Model, as they are each describing the same real-world concepts from two different angles”.

The Federal Health Information Model is a UML construct defining classes of data with linked terminological value sets proposed as reference values for attributes in the model. There are two classes proposed which directly relate to documentation of the clinical use cases section.

Status – the FHIR®/openEHR archetype for Adverse Reaction Risk is in its fourth review round as of November 2015.

http://www.openehr.org/ckm/ (search for Adverse Reaction Risk)

Data elements that could be encoded incude:

• Substance

• Status

• Criticality

• Reaction mechanism

• Substance category

• Certainty

• Manifestation

• Severity of reaction

• 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

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

Use to provide a single place within the health record to document a range of clinical statements about adverse reactions, including:

• record a clinical assessment of the individual’s propensity for a potential future reaction upon re-exposure; and

• record cumulative information about the reaction to each exposure

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

  • to support direct clinical care of an individual

Use to record information about the risk of adverse reactions to a broad range of substances, including:

• incipients and excipients in medicinal preparations

• biological products

• metal salts

• organic chemical compounds

Adverse reaction may be:

• an immune mediated reaction - Types I-VI (including allergic reactions and hypersensitivities)

• a non-immune mediated reaction:

  • pseudo-allergic reactions

  • side effects

In clinical practice, distinguishing between immune-mediated and non-immune mediated reactions is difficult and often not practical. Identification of the type of reaction is not a proxy for seriousness or risk of harm to the patient, which is better expressed by the manifestation in clinical practice.

The risk of an adverse reaction event or manifestation should not be recorded without identifying a proposed causative substance or class of substance. If there is uncertainty that a specific substance is the cause, this uncertainty can be recorded using the ‘Status’ 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 adverse reaction archetype/FHIR® resource with the ‘Status’ set to an initial state of ‘Suspected’ so that adverse reaction checking can be activated in clinical systems. Once the substance, agent or class is later proven not to be the cause for a given reaction then the ‘Status’ can be modified to ‘Refuted’.

This archetype/FHIR® resource has been designed to allow recording of information about a specific substance (amoxicillin, oysters, or bee sting venom) or, alternatively, a class of substance (eg 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 archetype/FHIR® resource has deliberately focused on identifying a pragmatic data set that are used in most clinical systems or will be suitable for most common clinical scenarios, however it permits extension of the model when additional detail is required, for example 'Reaction details', 'Exposure details', and 'Reporting details' slots. 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 risk in a health record involves the clinical assessment that a potential hazard exists for an individual if they are exposed to the same substance/agent/class in the future – that is, a relative contraindication - and 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/agent again, for example, following a manifestation of a life-threatening anaphylaxis, then the 'Criticality' data element should be amended to ‘High’.

A formal Adverse Event Report to regulatory bodies is a document that will contain a broad range of information in addition to the specific details about the adverse reaction. The report could utilize parts of this Risk of adverse reaction archetype/FHIR® resource plus include additional data as required per jurisdiction.

An adverse reaction or allergy/intolerance list is a record of all identified propensities for an adverse reaction for the individual upon future exposure to the substance or class, additionally providing potential access to the evidence provided by details about each reaction event, such as manifestation.

Valuable first-level information that could be presented to the clinician when they need to assess propensity for future reactions are:

• statements about previous clinical manifestations following exposure

• source of the information/reporter

• ‘Criticality’ flag.

Second-level information can be drawn from each exposure event and links to additional detailed information such as history, examination and diagnoses stored elsewhere in the record, if it is available.

The archetype is not to be used for recording physiological reactions to physical agents, such as heat, cold, sunlight, vibration, exercise activity, by infectious agents or food contaminants. Use archetypes/FHIR® resources for Problem/Diagnosis (openEHR) or Conditions (FHIR®).

Not to be used to record adverse events, including failures of clinical process, interventions or products. For example:

• abnormal use or mistakes/errors made in maladministration of an agent or substance

• incorrect dosage

• mislabeling

• harm or injury caused by an intervention or procedure

Not to be used to record an adverse reaction where the substance is unknown. Use EVALUATION.problem_diagnosis or CLUSTER.symptoms to record as part of the health record until a possible substance is identified.

Not to be used to record reactions to transfusions of blood products. Use a specific archetype for the purpose.

Not to be used as a proxy for an Adverse Event Report. See above for how it may be used as one component of an Adverse Event Report.

Not to be used for recording alerts.

Not to be used for recording failed therapy.

Not to be used for the explicit recording of an absence (or negative presence) of a reaction to 'any substances' or to identified substances, for example ‘No known allergies or adverse reactions’ or ‘No known allergies to Penicillin’. Use the EVALUATION. exclusion-adverse_reaction archetype to express a positive statement of adverse reaction exclusion.

Not to be used for the explicit recording that no information could be obtained about the adverse reaction status of a patient. Use the EVALUATION.absence archetype to record that a positive statement that information could not be obtained, for example, if a non-cooperative patient refuses to answer questions.

After considering reference information models from various standards development organizations and other national or regional sources, this inclusive information model was synthesized. The purpose of the model is to provide a conceptual framework to understand and align the various models but does not replace the individual models. (The details on each of the source information models are available in the appendices)

The image below illustrates the inclusive information model and shows the relationship between the three classes included in the model. The Propensity class is the centerpiece. A propensity class may be associated with zero-to-many Adverse Reaction classes and zero-to-many Adverse Sensitivity Test Result classes.

The following tables depict the three classes and their data elements. Only data elements specific to the adverse sensitivity use case are shown. Generic data elements such as date, time, patient and provider identifiers are omitted.

Table: Overview of the propensity class and a description of the associated data elements

Table: Overview of the adverse reaction class and a description of the associated data elements

Table: Overview of the adverse sensitivity class and a description of the associated data elements

There were other published allergy and hypersensitivity information models being considered at the initial drafting of this document in 2014, which included epSOS, openEHR, US Federal Health Information Model and UK NHS Connecting for Health Information Model. Their analysis fed into the creation of the inclusive model. Since then, HL7®-related information models, especially FHIR®, have become increasingly popular. Therefore, this document focuses more on these models. The analyses of the other models can be found in the Appendix. Note that the information may not be up-to-date, and some of the projects which created the models may no longer be active (e.g. the epSOS project concluded in 2014).

The Consolidated Clinical Document Architecture (C-CDA) specification (release 1.1 and 2.0) is required for communication of clinical data at transitions of care by the Office of the National Coordinator (ONC) for Health IT in the US. The ONC 2015 Edition Final Rule updated this requirement to specify the 2.1 version for Meaningful Use Stage 3 certification. The 2.1 C-CDA version includes an updated Allergy - Intolerance Observation (V2) 2.16.840.1.113883.10.20.22.4.7 template which includes a new Criticality Observation 2.16.840.1.113883.10.20.22.4.145 (replacing the previous Severity Observation (V2) at the allergy propensity level – the Severity Observation (V2) continues to be used in the Reaction Observation (V2)). The other relevant templates for use cases in section 3 are: Allergy Concern Act (V3) 2.16.840.1.113883.10.20.22.4.30 and Result Observation (V2) 2.16.840.1.113883.10.20.22.4.2.

The latest information about the HL7® C-CDA® standard can be found here:

This template reflects an ongoing concern on behalf of the provider that placed the allergy on a patient’s allergy list. As long as the underlying condition is of concern to the provider (i.e., as long as the allergy, whether active or resolved, is of ongoing concern and interest to the provider), the statusCode is “active”. Only when the underlying allergy is no longer of concern is the statusCode set to “completed”. The effectiveTime reflects the time that the underlying allergy was felt to be a concern.

The statusCode of the Allergy Concern Act is the definitive indication of the status of the concern, whereas the effectiveTime of the nested Allergy - Intolerance Observation is the definitive indication of whether or not the underlying allergy is resolved.

The effectiveTime/low of the Allergy Concern Act asserts when the concern became active. This equates to the time the concern was authored in the patient's chart. The effectiveTime/high asserts when the concern was completed (e.g., when the clinician deemed there is no longer any need to track the underlying condition).

The IPS is designed to provide clinical information to assist care across any jurisdictional (e.g. local, regional, state/provincial, national) or organizational border by providing a minimal but not exhaustive data set useful for subsequent clinical care scenarios. It emphasizes the data required and the associated business rules to support use and the necessary conformance of the use case for an international patient summary. The ISO TC215 International Patient Summary includes a section on Allergies and Intolerances.

The IPS includes the following conformance attributes:

The Allergies and Intolerance section of IPS data set includes:

Additional information about FHIR® implementation guide of the International Patient Summary can be found : .

This domain analysis model for allergy records was developed by the HL7 Patient Care Work Group and has been used to inform the allergy/intolerance modeling in the C-CDA® and FHIR® specifications.

http://www.hl7.org/implement/standards/product_brief.cfm?product_id=308

Patient Care Domain Analysis Model

Selected attribute definitions