SNOMED CT
Content Improvement Project
Elaboration phase
Project ID: artf6262
Topic: Allergic state - Immune hypersensitivity disorder
Date 2012-12-04
Version 2.3
Amendment History
Version
Date
Editor
Comments
0.01
20111109
Bruce Goldberg
First draft for comments
1.0
20120222
Bruce Goldberg
Second draft
1.1
20120318
Bruce Goldberg
Third draft revisions including metrics
1.2
20120325
Bruce Goldberg
Fourth draft revisions
2.0
20120730
Bruce Goldberg
Final revisions
2.1
20120808
Bruce Goldberg
2.2
20120822
Bruce Goldberg
2.3
20121204
Bruce Goldberg
Retirement of Immune hypersensitivity disorder
with replacement by allergic condition
Addition of new qualifier values for defining
hypersensitivity condition, allergic condition and
allergic sensitization
Change to concept model for allergic disposition
involving substitution of “after” attribute for “has
manifestation” and role grouping after allergic
sensitization with causative agent x to represent
allergy to x concepts
Additional edits including discussion of
propensity to adverse reactions to substance
Further refinement of allergy definitions
Review Timetable
Review date
Responsible owner
Comments
YYYYMMDD
Person/group responsible
Summary of action
(remove or add rows if necessary)
© International Health Terminology Standards Development Organisation 2012. All rights reserved.
SNOMED CT® was originally created by the College of American Pathologists.
This document forms part of the International Release of SNOMED CT® distributed by the International Health Terminology Standards
Development Organisation (IHTSDO), and is subject to the IHTSDO’s SNOMED CT® Affiliate Licence. Details of the SNOMED CT® Affiliate
Licence may be found at http://www.ihtsdo.org/our-standards/licensing/.
No part of this document may be reproduced or transmitted in any form or by any means, or stored in any kind of retrieval system, except by
an Affiliate of the IHTSDO in accordance with the SNOMED CT® Affiliate Licence. Any modification of this document (including without
limitation the removal or modification of this notice) is prohibited without the express written permission of the IHTSDO.
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may have been modified and may be out of date. Any recipient of this document who has received it by other means is encouraged to obtain
a copy directly from the IHTSDO [or a Member of the IHTSDO. Details of the Members of the IHTSDO may be found at
http://www.ihtsdo.org/members/].
Elaboration phase
Page 2 of 22
Table of Contents
1 Glossary ................................................................................................................................ 4
1.1 Domain Terms............................................................................................................................. 4
2 Introduction............................................................................................................................ 5
2.1 Purpose....................................................................................................................................... 5
2.2 Audience and stakeholder domain .............................................................................................. 5
3 Solution Development ........................................................................................................... 7
3.1 Initial Design ............................................................................................................................... 7
3.2 Iteration One ............................................................................................................................. 15
3.3 Iteration Two .. .......................................................................................................................... 16
4 Recommendation ................................................................................................................ 17
5 Quality program criteria ....................................................................................................... 18
5.1 Quality metrics .......................................................................................................................... 18
5.2 Use case scenarios ................................................................................................................... 19
5.3 Test cases................................................................................................................................. 19
6 Updated Project Resource Estimates .................................................................................. 20
6.1 Scope of construction phase ..................................................................................................... 20
6.2 Expected project resource requirement category ...................................................................... 20
6.3 Projection of remaining overall project resource requirements .................................................. 20
7 APPENDIX .......................................................................................................................... 21
7.1 Formal ontological model of allergy conditions .......................................................................... 21
Elaboration phase
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1 Glossary
1.1 Domain Terms
Hypersensitivity
(general)
Hypersensitivity
condition
Hypersensitivity
reaction
Allergy1
(general)
Allergic condition
Allergic
disposition
Allergic reaction
Allergic
sensitization
Objectively reproducible symptoms or signs initiated by exposure to a
defined stimulus at a dose tolerated by normal persons
The disposition to develop hypersensitivity or the manifestation of a
such disposition
A pathological process initiated by exposure to a defined stimulus at a
dose tolerated by normal persons. It may be the manifestation of a
disposition to hypersensitivity.
Allergy is a type of immune-mediated hypersensitivity in which the
immune response is generally directed towards a foreign antigen and
which results in tissue injury, which is usually transient.
The disposition to develop an allergic reaction, the allergic reaction
itself or it’s consequences
The disposition to develop an allergic reaction. Synonym “allergy”,
“allergic disposition”
A pathological immune process generally directed towards a foreign
antigen, which results in tissue injury which is usually transient. It is
the manifestation of the allergic state. It is most often applied to type I
hypersensitivity but other hypersensitivity types especially type IV
(e.g. allergic contact dermatitis) may be involved
A process characterized by a humoral or cell-mediated immune
response to a foreign antigen resulting in the production of specific
antibodies and/or immune cells which may then lead to an allergic
disposition. An allergic disposition requires the presence of a
sensitized state but a sensitized state does not necessarily lead to an
allergic disposition. Allergic sensitization may also refer to the
persistent state of specific antibody/immune cell presence following an
allergic sensitization process
Qualifier value definitions for pathological process role
Hypersensitivity
process
Allergic process
Allergic
sensitization
process
1
A pathological process that results in a hypersensitivity process or
disposition
A type of immune hypersensitivity process that results in an allergic
disposition or process.
A type of allergic process that results in an allergic sensitization
process or sensitized state
Revision of 2003 EAACI/WAO definition of allergy
Elaboration phase
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2 Introduction
2.1 Purpose
The purpose of this project is to consider further review of the Allergic state and Immune
hypersensitivity disorder hierarchies. The merger of allergic disorder" with "immune hypersensitivity
disorder" had led Psoriasis and Graves disease to be classified as allergic disorders.
The definition of allergic/immune hypersensitivity disorder will need to be revised in order to
distinguish autoimmune from allergic disorders. In addition, the relationship between allergic disorders,
states and reactions needs additional review.
SNOMED CT projects transition from Inception Phase  Elaboration Phase  Construction Phase 
Transition Phase. This document describes the Elaboration Phase.
It follows on from an Inception Phase report, which describes the detail of the problem to be
addressed and its scope boundaries
The purpose of the Elaboration Phase document(s) is to document one (or more) possible technical
solutions that have been developed and tested, and to recommend and provide a detailed
specification of a preferred solution to be taken forward to the construction phase.
2.2 Audience and stakeholder domain
The audience for this document includes all standards terminology leaders, implementers and users
developing core and extension content in the clinical finding/disorder hierarchy but is especially
targeted at those with an interest in documenting adverse reactions.
A further significant audience is the community of SNOMED authors that may be requested to
implement the recommended specification.
2.2.1 Stakeholders
The National Cancer Institute (Common Terminology Criteria for Adverse Events, CTCAE)
Medical Dictionary for Regulatory Activities (MedDRA)
National Health Service (NHS), United Kingdom ([email protected])
IHE Strategic Development Medication Management Subcommittee
World Health Organization
European Academy of Allergy and Clinical Immunology (EAACI) the
World Allergy Organization (WAO).
American Academy of Asthma, Allergy and Immunology
American College of Asthma, Allergy and Immunology
Content developers and end-users (clinical allergists, immunologists, dermatologists,
pulmonologists otolaryngologists and rheumatologists).
HL-7 patient care work group
Elaboration phase
Page 5 of 22
A copy of this document has been sent to members of the Care plan, HL7 Patient Care Work
Group (André Boudreau, Elaine Ayres , Stephen Chu) for comment.
“After reading through your v3.0 document, I would like to suggest that the scope include
the SCT concepts related to intolerance and to propensity”.
André Boudreau
Co-Lead, Care plan, HL7 Patient Care Work Group
Chair, Individual Care pan Canadian Standards Collaborative Working Group
Elaboration phase
Page 6 of 22
3 Solution Development
3.1 Initial Design
3.1.1 Outline of initial design
The design of this project is based on the following criteria
1. Creation of a text definition that distinguishes allergic disorders from other types of
immunologically-mediated hypersensitivity such as autoimmunity by refining the EAACI/WAO
definitions. This is the background behind the original request.
2. Creation of text definitions for 106190000, allergic state (disorder) and 418925002 immune
hypersensitivity reaction (disorder)
3. Reorganizing the three hierarchies noted above in consideration of the revised definitions.
4. Improving the concept models for allergic disorder, allergic state and allergic reaction using a
formal ontological approach in order to clearly represent the associations between them.
As this project consists of several components, the logical approach would be to divide the project into
individual tasks in order of increasing complexity.
Phase 1: In order to accomplish the successive phases of this project, one must consider the overall
approach taken which incorporates the ideas described by Schulz et. al. in which clinical findings and
disorders can be reimagined as pathological structures, dispositions or processes and their
disjunction, conditions (SDP)2. With this in mind, 106190000, allergic state (including allergy to x) may
be considered a pathological disposition while 418925002, immune hypersensitivity reaction (allergic
reaction) a pathological process. The concepts residing under 421668005, immune hypersensitivity
disorder (allergic disorder) are ambiguous as to whether they represent pathological dispositions or
processes and therefore would be considered to be conditions3. The initial stages of this project would
call for the retirement of Immune hypersensitivity disorder and 421976005, hypersensitivity disorder
with replacement by 2 new terms, hypersensitivity condition and allergic condition. The notion of an
immune hypersensitivity condition as distinct from an allergic condition would be eliminated. Allergic
condition would be assigned parents of disorder of immune function4 and hypersensitivity condition
2
Stefan Schulz, Kent Spackman, Andrew James, Cristian Cocos and Martin Boeker J Biomed Semantics 2
Suppl 2():S6 (2011) PMID 21624161
3
Allergic diseases such allergic rhinitis could be interpreted as dispositions in the absence of the relevant
allergen or as processes (allergic reactions) after exposure to the allergen.
4
Due to the weak definition of 414029004, Disorder of immune function (disorder) using has definitional
manifestation immune system finding, it has been decided to not add this concept as a parent of allergic
condition.
Elaboration phase
Page 7 of 22
and defined as a pathological immune process or the disposition to undergo such a process usually to
an external agent.
Changes to the concept model of Allergic conditions
Currently, Immune hypersensitivity disorder (allergic disorder) is fully defined as:
Is A Disease
Due to Immune hypersensitivity reaction (allergic reaction).
This definition appears to be suboptimal. The proposal is to redefine hypersensitivity and allergic
conditions using the pathological process role analogous to autoimmune and infectious disorders with
which these share similarities in not being able to be represented by the associated morphology
attribute or an abnormal structure. This would require the reorganization as well as creation of several
additional qualifier values under pathological process (qualifier value) as shown below:
Pathological process (qualifier value)
autoimmune (qualifier value)
hypersensitivity (qualifier value)5
allergic process (qualifier value)
sensitization (qualifier value)
Hypersensitivity condition would thus be completely defined as6:
|disease|
|pathological process|=|hypersensitivity|
and allergic condition as:
|hypersensitivity condition|
|pathological process|=|allergic process|
The current children of immune hypersensitivity disorder would be moved under Allergic condition.
Phase 2: In the second phase of this project, immune hypersensitivity reaction would be retired and
419076005, allergic reaction unretired as its replacement. The allergic reaction hierarchy would be
added under allergic condition thus defining allergic reaction as a hypersensitivity reaction and an
allergic condition. There are several concepts residing under the current immune hypersensitivity
reaction hierarchy that represent specific types of immune (not necessarily allergic) reactions
represented by the Gell and Coomb’s classification and are used to define the associated disorders.
These can be aggregated under a new concept, immune hypersensitivity reaction by mechanism
analogous to immune hypersensitivity disorder by mechanism which would represent the five types of
5
Currently a child of mechanisms (qualifier value)
6
The attribute value pairs |due to|=hypersensitivity reaction and |due to|=immune hypersensitivity reaction from
the original definitions of hypersensitivity disorder and immune hypersensitivity disorder respectively will not be
included in the new definitions of hypersensitivity condition and allergic condition.
Elaboration phase
Page 8 of 22
hypersensitivity reactions as decribed by Gell and Coombs. 106190000, allergic state (disorder) is
currently primitive with no defining attributes and a single parent, 420134006, propensity to adverse
reactions. Allergic state would be added under allergic condition thus helping to define the former.
Allergic state has a child, allergic disorder by allergen type. Allergic state would be removed as a
parent of allergic disorder by allergen type which would thus become a subtype only of allergic
condition and can be used to aggregate terms of the type allergic condition (disorder) x to allergen y
(i.e. 449729000, allergic rhinitis due to house dust mite). The children currently residing under allergic
disorder by allergen type are the following:
Allergy to gauze
Allergy to plant
Allergy to substance
House dust mite allergy
Tape allergy
Allergy to substance would be made a child of allergic state and the remaining terms would be merged
under allergy to substance. Text definitions would be created for allergy to gauze, allergy to plant,
house dust mite allergy and tape allergy to indicate that the allergy is to the substance derived from
these physical objects and organisms.
Changes to the concept model of allergic state (allergy)
Allergy to various substances is presently defined using the causative agent role implying that the
allergy (disposition) is caused by the allergen. In actuality, the allergen causes the allergic reaction
which is the realization of the allergic disposition. In order to link the allergen to the disposition without
invoking a causative relation between the allergen and the disposition, a new concept of allergic
sensitization would be created. Allergic sensitization would be defined as the process or state induced
by a humoral or cell-mediated immune response to a foreign antigen characterized by the presence of
specific antibodies and/or immune cells and would be represented in SNOMED as a subtype of
allergic condition with pathological process sensitization. It is believed that the process or state of
sensitization to a particular allergen would necessarily precede the disposition which could then be
realized as an allergic reaction upon re-exposure to that allergen. Allergy (disposition) would thus be
defined as:
|allergic disposition|
|allergic condition|
|propensity to adverse reactions|,
|after|=|allergic sensitization|
As the specific allergen causes the sensitization, allergy to x can be defined using the after and
causative agent roles in a role group as illustrated:
allergy to penicillin
|allergy to drug|:
{|after|=|allergic sensitization|,
|Causative agent|=|penicillin|}
Elaboration phase
Page 9 of 22
Further scrutiny of propensity to adverse reactions to substance (disorder) reveals that it is modeled with
causative agent substance. This is analogous to the issue of allergy to substance, in that the substance does not
cause the propensity (disposition). This would be problematic in terms of the proposed definition of allergic
disposition being a subtype of propensity to adverse reactions to substance (disorder). Examining the children of
Propensity to adverse reactions to substance, it appears that the majority are in fact just allergies to substance
as shown below.
It would therefore be desirable to retire Propensity to adverse reactions to substance as maybe A allergy to
substance while moving most of its children under allergy to substance. The relatively few non-allergy terms will
need to be moved under hypersensitivity condition for now but may eventually need to reside under a new
class of hypersensitivity disposition
There is a significant degree of misclassification of terms in all 3 allergy-related hierarchies stemming
not only from unclear definitions of these conditions but also the use of common names that falsely
imply allergy as well as a lack of understanding of the immune mechanisms underlying some of the
concepts. These issues will also be addressed in phase 2.
Elaboration phase
Page 10 of 22
Phase 3: The final phase of this project can be considered for future implementation as it may have
a more global impact on SNOMED. Thought should be given to creation of three top level nodes under
disease or clinical findings (TBD) for pathological structure, pathological disposition and pathological
manifestation (process). Specific concepts in which the FSN clearly implies a pathological structure,
disposition or manifestation can be added under these organizing nodes. As an example, propensity
to adverse reactions and allergic state have an implict meaning of disposition whereas hypersensitivity
reaction and allergic reaction have an implicit meaning of a manifestation or process.
Lastly, consideration can be given to further expanding the hypersensitivity qualifier value hierarchy by
including hypersensitivity types7 and its children type I hypersensitivity and type IV hypersensitivity
under hypersensitivity (qualifier value) with the addition of types I, II, III and V in order to refine the
definitions of those hypersensitivity conditions found under immune hypersensitivity disorder/reaction
by mechanism.
Pathological process (qualifier value)
Autoimmune (qualifier value)
Hypersensitivity (qualifier value)
Hypersensitivity types (qualifier value)
Type I hypersensitivity (qualifier value)
Type II hypersensitivity (qualifier value)
Type III hypersensitivity (qualifier value)
Type IV hypersensitivity (qualifier value)
Type IV hypersensitivity (qualifier value)
Allergic process (qualifier value)
Type I hypersensitivity (qualifier value)
Sensitization (qualifier value)
The resulting reorganization and concept model for allergic conditions are illustrated below:
7
Currently a child of types (qualifier value)
Elaboration phase
Page 11 of 22
Autoimmune
disorder
Pathological
process
Autoimmun
e
Is A
Disease
Disorder of
immune
function
Is A
Pathological
process
Is A
Disease
Is A
Hypersensit
ivity
Is A
Is A
Hypersensitivity
condition
After
Is A
Is A
Allergy
Is A
Hypersensitivity
reaction
Allergic
sensitization
Is A
Is A
Adverse
reaction
Propensity to
adverse
reactions
Allergic rhinitis
Is A
Allergy to
substance
RG
Causative agent
Allergic
condition
Substance
after
Is A
Pathological
process
Is A
Pathological
process
Is A
Complication
Allergic
sensitization
Sensitizatio
n
Qualifier value hierarchy
Qualifier
value
Allergy
Is A
Allergic
reaction
Is A
Patholo
gical
process
Allergic
reaction to
substance
Autoim
mune
Is A
Hyperse
nsitivity
Causative agent
Allergy
Substance
Sensitiz
ation
3.1.2 Significant design or implementation decisions / compromises
The design of this project is based on the ontology design pattern suggested by Schulz et.al. 2 in which
pathological entities can be viewed as either pathological structures, dispositions or processes (SDP)
with the ability to obscure these distinctions until required as for example at the time a diagnosis is
being recorded. It is hoped that the design being proposed for allergy can be generalized to include
other pathologic entities in which a distinction eventually needs to be made as to whether a clinical
state represents a pathological structure disposition or process. A decision was also made to create a
more robust concept model for allergic disorder (condition), allergic state and allergic reaction by
Elaboration phase
Page 12 of 22
including the pathological process attribute similar to the model developed for infections. Finally, the
concept model for allergy to substance was further refined via a role group incorporating has
definitional manifestation allergic sensitization and causative agent some allergenic substance. It is
believed that this approach is more scientifically and ontologically correct than the current definition of
allergy to substance in which the allergen appears to directly cause the allergy (disposition).
While much of the above changes may be implemented through batch edits, there will need to be a
significant amount of manual review of all three hierarchies in order to correct inconsistencies based
on unclear definitions of some concepts, the use of common names that falsely imply allergy and the
assignment of incorrect immune mechanisms as previously alluded to. Some of these issues are
illustrated below:
Concept
Jones-Mote type hypersensitivity
Hypersensitivity angiitis
Anaphylactoid glomerulonephritis
Allergic encephalitis
Conjunctivitis associated with autoimmune
skin disorder
Humoral immunologic aplastic anemia
Allergic rhinitis due to grass pollens (tree
pollens/weed pollens)
Anaphylactoid reaction
Non-steroidal anti-inflammatory drug allergy
Postinfective Henoch-Schönlein purpura
Issue
1. Implies a disposition but meaning but
should be a process.
2. Currently a child of allergic state but is a
actually a type of delayed type
hypersensitivity
Currently a descendant of allergic disorder by
body site affected. Not allergic.
Currently a descendant of allergic disorder by
body site affected. Not allergic.
Currently a descendant of allergic disorder by
body site affected. Not allergic.
Currently a descendant of allergic disorder by
body site affected. Not allergic.
Currently a descendant of allergic disorder by
body site affected. Not allergic.
Currently children of seasonal allergy but
appear to be conditions
Is a child of acute allergic reaction.
Anaphylactoid reactions are kinds of nonallergic hypersensitivity reactions.
This concept and its children most likely
represent anaphylactoid sensitivity.
Is a descendant of allergic disorder of skin.
Not allergic.
The proposed organization and model for allergic conditions is based on earlier efforts of the events,
conditions and episodes project group in which a more formal ontological representation was
constructed (see appendix). As that model required DL formalisms including universal restriction which
are not currently supported by SNOMED as well as the introduction of several new attributes derived
from BioTop, it was decided that a reasonable compromise could be attained using elements of the
more formal ontological approach such as the inclusion of SDP while utilizing current SNOMED roles.
Elaboration phase
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3.1.3 Evaluation of Design
Implementation of the proposed model for allergic conditions requires:
1. Creating text definitions for hypersensitivity and allergic condition, state (disposition) and
reaction
2. Merging immune hypersensitivity disorder (allergic disorder), allergic state and immune
hypersensitivity reaction (allergic reaction) into a single hierarchy called allergic condition while
retiring immune hypersensitivity condition and moving its children under allergic condition.
3. Creation of two new qualifier values, allergic (process) and sensitization and perhaps moving
the existing hypersensitivity (qualifier value) from mechanisms (qualifier value) to pathological
process (qualifier value).
4. Addition of a new allergic condition concept “allergic sensitization” required for the definition of
allergic state.
5. Using the pathological process role to define hypersensitivity condition, allergic condition,
allergic state and allergic reaction
6. Using the after and causative agent roles in a role group to link the allergic sensitization to its
causative allergen in order to better define the allergic state
Current model
hypersensitivity disorder
|disease|
|due to|=|hypersensitivity reaction|
immune hypersensitivity disorder
|hypersensitivity disorder|
|due to|=|immune hypersensitivity reaction|
allergic state
|propensity to adverse reactions|
allergy to substance
|propensity to adverse reactions to substance|
|allergic disorder by allergen type|
|causative agent|=|substance|
hypersensitivity reaction
|adverse reaction|
immune hypersensitivity reaction
|hypersensitivity reaction|
Proposed model
hypersensitivity condition
|disease|
|pathological process|=|hypersensitivity|
allergic condition
|hypersensitivity condition
|disorder of immune function|
|pathological process|=|allergic process|
allergic dipsosition
|allergic condition|
|after|=|allergic sensitization|
|propensity to adverse reactions|
allergy to substance
|propensity to adverse reactions to substance|
{|after|=|allergic sensitization|, |causative
agent|=|substance|}
hypersensitivity reaction
|adverse reaction|
|hypersensitivity condition|
allergic reaction
|hypersensitivity reaction|
|allergic condition|
These changes are expected be implemented with minimal impact on existing SNOMED content. The
model will initially be evaluated in the testing environment (UAT bundle) to assess the impact of some
of the modeling steps and to determine the extent of possible batch editing.
Elaboration phase
Page 14 of 22
3.1.3.1 Exceptions and Problems
1. The proposed model excludes pathological structures (the “S” in SDP) from consideration as
there is some difficulty defining an “allergic” structure.
2. Most of the children being moved under allergic condition contain the word “disorder”in the
FSN. Consideration should be made to renaming these.
3. The notion of an allergic condition as a truly disjoint class is currently not supported by the DL
formalism used by SNOMED.
4. A significant amount of manual review will be required in order to insure that some of the
existing content is classified correctly.
5. The addition of a top level “condition” node populated by subhierarchies of pathological
structures, dispositions and processes will be deferred for a future implementation as it is
expected that this will have a more global effect on existing SNOMED content.
6. There is still some uncertainty as to whether the condition class and its descendants should be
a child of disease or of clinical finding.
3.1.3.2 Design Strengths
The proposed design will result in a more robust model for allergy content with clear interrelationships
between the three existing allergy hierarchies and a more scientifically and ontologically correct
definition of the important allergy to substance class. Additional cleanup of the existing hierarchies will
result in improved classification and therefore retrieval of this content. The design allows for the
ambiguity expressed in the FSNs of allergic disorders as to whether they represent dispositions or
processes. The true nature of these terms may be asserted at the time of documentation by adding a
second parent such as pathological disposition or pathological process8 or by use of defining
properties for each specialization class as illustrated below:
Allergic rhinitis (currently active/continuing)
Is A Allergic rhinitis (condition)
Some role=some role=active/continuing
Allergic rhinitis (disposition)
is A Allergic Rhinitis (condition)
Some role=propensity to develop symptomatic allergic rhinitis
3.1.3.3 Design Weakness
Design weaknesses are discussed under section 3.1.3.1 Exceptions and Problems.
3.2 Iteration One
3.2.1 Outline of revised design
Redesign the Solution Identify objectives of iteration, and the major changes to previous design
Communicate the revised design
8
When such concepts are created under the proposed top level condition node as discussed.
Elaboration phase
Page 15 of 22
3.2.2 Significant design or implementation changes
3.2.3 Evaluation of Revised Design
3.2.3.1 Exceptions and Problems
3.2.3.2 Design Strengths
3.2.3.3 Design Weakness
3.2.3.4 Design Risks
Description of risk
Importance
Mitigation plan
3.3 Iteration Two ..
Elaboration phase
Page 16 of 22
4 Recommendation
4.1.1 Detailed design final specification
See phases 1-3 pages 7-8 and in particular the figures on page 9 and 10, which illustrate how the
revised allergy hierarchies would appear after implementing the proposed solution.
4.1.2 Iteration plan
Elaboration phase
Page 17 of 22
5 Quality program criteria
5.1 Quality metrics
5.1.1 Quality metric 1
Component Characteristic and Description
Hierarchy
Char:
Disambiguate immune
hypersensitivity disorder from
allergic disorder
Metric
Allergic disorder
Target
Result
100%
is A
Descr:
Immune hypersensitivity
disorder
5.1.2 Quality metric 2
Component Characteristic and Description
Logic definitions of
Char:
Clarify relationship between
Metric
allergic disorder, allergic state
is A
disorder, Allergic
and allergic reaction
Pathologic structure or
process
reaction hierarchies
Result
Allergic disorder
concepts in Allergic
state and Allergic
Target
90%
Descr:
hasOutcome of Allergic
reaction
Allergy to x
is A
Pathologic disposition
100%
hasAgentOfRealization
x
Allergic reaction to x
is A
Allergic process
isRealizationOf
100%
Allergy to x
hasOutcome(only)
Allergic disorder
Elaboration phase
Page 18 of 22
5.2 Use case scenarios
5.2.1 Use case 1
Representation of Allergy to X i.e the disposition to developing an allergic reaction after exposure to
allergen X
5.2.1.1 Fit with IHTSDO strategy
1B Problem list diagnosis
1D Allergy list
2A Medication / allergy management
5.2.2 Use case 2
Representation of specific allergic/immunologic disorders such as allergic rhinits
5.2.2.1 Fit with IHTSDO strategy
1B Problem list Diagnosis
There are 29 diagnoses on the SNOMED CT core problem list that refer to allergy, anaphylaxis or
hypersensitivity. Allergic rhinitis is the top 11th diagnosis.
2A Medication / allergy management
Relevant for decision support algorithms involving medication management in allergic individuals. An
example would be an alert regarding use of radiocontrast agents in those with a history of an atopic
disorder.
5.2.3 Use case 3
Representation of specific allergic disorders caused by allergen X e.g. Allergic rhinitis due to pollen
5.2.3.1 Fit with IHTSDO strategy
1B Problem list diagnosis
1D Allergy list
2A Medication / allergy management
5.2.4 Use Case 4
Representation of Non-specified allergic reactions to allergen X such as allergic reaction to penicillin
5.2.4.1 Fit with IHTSDO strategy
1B Problem list diagnosis
There is a need to distinguish an episode of an allergic reaction to a particular substance occurring at
the time of an encounter from a disposition to an allergic reaction to a particular substance
5.2.5 Use Case 5
Representation of specific types of allergic reactions to allergen x such as anaphylactic reaction to
penicillin
5.2.5.1 Fit with IHTSDO strategy
1B Problem list diagnosis
5.3 Test cases
Elaboration phase
Page 19 of 22
6 Updated Project Resource Estimates
Estimate project size; Forecast project velocity and duration
Evaluate risks; Establish costs and articulate value; Plan deployment; Outline project lifecycle
6.1 Scope of construction phase
6.1.1 Skills required
Domain-specific knowledge of allergic and immune (including autoimmune) disorders would be
desirable.
6.1.2 Preventing recurrence of problem
Creating text definitions for allergic conditions and publishing clear modeling guidelines for allergic
conditions in the SNOMED CT editorial guide will ensure prevention of reoccurrence.
6.1.3 Division of project into stages
Due to the overall size of the project and limited resources available, it is recommended that the
project be divided into discrete stages in order to begin delivering value to stakeholders in a timely
manner as discussed on pages 7-9.
6.2 Expected project resource requirement category
The project is large impacting up to 3,000 concepts residing among several hierarchies and as has
been suggested by one reviewer could be tackled as part of an even larger effort to revise the
approach to adverse reactions in general. It should be addressed in phases as previously discussed.
6.3 Projection of remaining overall project resource requirements
6.3.1 Expected project resource requirement category
The project is large and as has been suggested by one reviewer could be tackled as part of a larger
effort to revise the approach to adverse reactions.
6.3.2 Expected project impact and benefit
The project impact is HIGH – significant improvement to a minority but high profile use case. The
benefit is a consistent, rational approach to classifying allergic and other immune disorders.
6.3.3 Indicative resource estimates for construction, transition and maintenance:
Construction and transition phase: Approximately 2,269 will need to be reviewed and many
remodeled.
Maintenance phase: 1600 new allergic reaction to x concepts potentially to be authored in first 3 years
based on approximate number of existing allergy to x concepts.
Elaboration phase
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7 APPENDIX
7.1 Formal ontological model of allergy conditions
hasLocus some
Pathologic
structure
isA
Allergic disorder
isA
*For delayed type
hypersensitivity this could
be Th1 memory T-cells
Condition
Pathologic
structure or
process
isA
Allergen-specific
IgE*
hasLocus some
Immune system
structure
isOutcomeOf some
hasLocus some
bearerOf some
hasOutcome only
isA
isA
Pathologic
disposition
isA
Allergic disposition
Allergy to X
hasAgentOfRealization
isRealizationOf some
hasAgent some
Pathologic process
isA
Allergic process
isA
hasOutcome only
Allergic reaction to
X
Ige-mediated
allergic
sensitization
Allergen X
hasAgent some
isA
isA
Allergic
sensitization
BioTop Relation
Definition
Domains
Ranges
(object property)
hasAgent
A participant of a process, with the additional Processual entity
condition that the component instance is
causally active in the relevant process.
Elaboration phase
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hasOutcome
participant which either
Processual entity
- a) comes into being during the process or
- b) undergoes some change during the
process and constitutes (one of) the main
result(s) of the process
outcomeOf
Inverse of hasOutcome
*hasAgentOfRealization A participant of a disposition that results in
Processual entity
Disposition
the realization of a process
isRealizationOf
Something that occurs can be the realization Processual entity
Disposition
of a function, a disposition, or a role
or Quality
or Role
hasLocus
relates a place with an entity which occurs,
Disposition
ImmaterialPhysicalEntity
inheres, or is part of it
ImmaterialNonphysicalEntity
MaterialEntity
ImmaterialPhysicalEntity
SpatialRegion
MaterialEntity
ProcessualEntity
Quality
Role
SpatialRegion
bearerOf
Inverse relation of inheresIn. Relates an
ImmaterialPhysicalEntity
Disposition
independent continuant to a dependent one
MaterialEntity
Function
(e.g. quality, state, function, or disposition)
SpatialRegion
ImmaterialNonphysicalEntity
Quality
Role
Elaboration phase
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