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IHTSDO-810 (artf6238) Burns

IHTSDO-810 (artf6238) Burns

2018-Jan-17

 

SNOMED CT

Content Improvement Project

Combined Inception and Elaboration phases

Project ID:

  

Topic:  

JIRA: IHTSDO-810

CollabNet: artf6238

Burns

Date:

15 March 2016

Version:

0.01

 

https://projects.jira.snomed.org/browse/IHTSDO-810

 

Amendment History

Version

Date

Editor

Comments

0.01

20160315

Sarita Keni

First draft for comments

 

 

 

(remove or add rows if necessary)

@Matt Cordell Apr 29, 2016 Requesting review of Version 0.01 of this document. Review template: JIRA IHTSDO-810(artf6238) Burns Documentation Review

Review Timetable

Review date

Responsible owner

Comments

20160607

Matt Cordell

Accepted

This final version of the document incorporates all reviewer feedback and author responses in Appendix E. See also Confluence Document Review page  

 

 

(remove or add rows if necessary)

 

Note: This document was reviewed by the Head of Terminology in March 2017: Provision approval with the noting that there is a need for a minor update in relation to modelling of 3rd and 4th degree burns. These concepts need to be modelled with FINDING SITE = Skin and subcutaneous tissue of <body structure>. Please see the document review page when constructing the tracker. See @Cathy Richardson for access. 

 

© International Health Terminology Standards Development Organisation 2012. All rights reserved.

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Table of Contents

 

1 Glossary

1.1 Domain Terms

Skin

The thin layer of tissue forming the natural outer covering of the body of a person or animal. (Oxford University Press, 2016)

Skin consists of two layers, the epidermis and dermis.  The epidermis has no vasculature and depends entirely on the dermis for nutrition.  The dermis consists of two layers: 1) the papillary layer consisting of capillaries, elastic fibers, and collagen; and 2) the reticular layer, consisting of thicker connective tissue, larger blood vessels, hair follicles, sebaceous glands, and sweat glands among other structures.  The skin rests on a layer of subcutaneous tissue, which then covers deeper structures such as muscle, bones, and joints. (Amirlak & Shahabi, 2015)

Burn

An injury to the skin or other organic tissue primarily caused by heat or due to radiation, radioactivity, electricity, friction or contact with chemicals. Skin injuries due to ultraviolet radiation, radioactivity, electricity or chemicals, as well as respiratory damage resulting from smoke inhalation, are also considered to be burns. (World Health Organization, 2016)

First degree burn

Burn injury limited to the epidermis layer of the skin

Synonyms: Epidermal burn, Superficial burn, Burn erythema

Second degree burn

Burn injury involving both the epidermis and dermis layers of the skin, subdivided into two types:

-  Superficial: Burn injury is limited to the papillary layer of the dermis

-  Deep: Burn injury extends into the reticular layer of the dermis

Synonyms: Partial thickness burn, Superficial partial thickness, Deep partial thickness

Third degree burn

Burn injury involving both the epidermis and dermis layers of the skin, and extending into the subcutaneous tissue

Synonym: Full thickness burn

Fourth degree burn

Burn injury involving the skin, subcutaneous tissue, and extending into underlying structures such as muscles, bones, and joints

Synonym: Deep full thickness burn

 

 

2 Introduction

2.1 Purpose

The purpose of this project is to consider the representation of content within the Burn (disorder) hierarchy, specifically naming conventions and modeling guidelines.

2.2 Audience and stakeholder domain

The audience for this document includes all standards terminology leaders, implementers, and users but is especially targeted at the community of clinicians or implementers who utilize SNOMED CT to represent burn <disorder> content within clinical information systems or for research purposes as well as SNOMED CT authors who may be requested to implement the recommended specification.

2.2.1 Input from stakeholders

SIRS: As of March 2016, there are only 5 requests related to burn <disorder> content in the IHTSDO SNOMED CT International Request Submission (SIRS) system.  These requests are listed in Appendix D. The low number of outstanding requests is likely because existing content in the Burn (disorder) hierarchy is already comprehensive.  However, Section 3.4 will detail the primary issue related to this content: inconsistent naming conventions and modeling.  One SIRS request refers to this issue:

Request ID 531381 (submitted 22 April 2015)

Request summary: Consistency required to ensure users are able to search easily and reduce ambiguousness of concept

Request description: Burn concepts are represented in SCT by several classification systems. Currently, older concepts contain references to older classification systems (e.g. first/second/third degree) as well as the newer classification system (e.g. superficial, partial thickness, full thickness). Many concepts that have been recently created only contain the newer classification term, and do not contain the older first/second/third term. We are concerned for the lack of consistency and while these older terms may not be the preferred term, they are still commonly in use and having some concepts with these synonyms and some without could confuse users into thinking there were gaps (even though the concepts exist).

IHTSDO: An IHTSDO SNOMED CT author also commented on the JIRA tracker for this project that current Burn (disorder) hierarchy content is inconsistently modeled, specifically, second and third degree burn content.  These comments are provided in Section 3.1 and addressed in Section 6.1.1.5. 

2.2.2 Degree of consensus on the statement of problem

Based on the artifact description as well as the stakeholder input provided above, it is clear that there is a strong consensus on the need for comprehensive and consistent representation of content in the Burn (disorder) hierarchy.  

 

3 Statement of the problem or need

3.1 Summary of problem or need, as reported

The IHTSDO content project title and description originally submitted on 24 January 2010:

Burns

JIRA: IHTSDO-810 | CollabNet: artf6238 https://jira.ihtsdotools.org/browse/IHTSDO-810

“Naming and modeling of “Burn” disorder concepts. Currently, burn concepts are represented in SNOMED CT by several classification systems.  Some concepts contain terms from classification systems that have either been superseded or are terms that are not international in usage.  Naming conventions and modeling guidelines are needed in this hierarchy. There are bout 800 *burn* (disorder) concepts.”

In addition, an IHTSDO SNOMED CT author provided the following comments on the JIRA tracker for this project (25 November 2015):

“There are about 160 concepts for Second degree burn. There are inconsistencies in concept modeling for finding sites. Some of them are modeled by skin structure but some are not. Therefore, not all of them are classified under 284196006|Burn of skin (disorder).

There are about 250 concepts for Third degree burn. Two issues need to be addressed. The first issue is that finding site should be 'skin structure' or more specifically 'structure of skin and subcutaneous tissue' instead of structure of a body region. The second issue is whether third degree burn should be subconcept of Burn of skin. The definition of third degree burn indicates the burn of skin (both epidermis and dermis layers).”

3.2 Summary of requested solution

The requested solution is to provide naming conventions and modeling guidelines to harmonize content within the Burn (disorder) hierarchy. 

3.3 Statement of problem as understood

The artifact description suggests that content in the Burn (disorder) hierarchy is based on several classification systems, some of which are outdated.  According to the artifact description as well as the stakeholder input, the representation of this content is inconsistent.  Naming convention and modeling guidelines are needed to harmonize existing content as well as new content that may be added in the future.

3.4 Detailed analysis of reported problem, including background

3.4.1 Scope of this project

Based on the artifact description, this document will focus on naming conventions and modeling guidelines for the subtype concepts of the 125666000 | Burn (disorder) hierarchy.  Additionally, some changes to the 48333001 | Burn injury (morphologic abnormality) hierarchy will also be suggested to support recommendations for modeling content in the Burn (disorder) hierarchy. 

3.4.2 Overview of this project

All content in this document is current as of the January 2016 SNOMED CT International Release. There are 839 Burn (disorder) concepts.  In general, existing Burn (disorder) content in SNOMED CT is well-organized into three primary patterns:

  • Burn of <body structure> (disorder) (214 concepts):

    • 37645002 | Burn of head AND/OR neck (disorder)

    • 52405000 | Burn of trunk (disorder)

    • 6055000 | Burn of upper limb (disorder)

    • 84677008 | Burn of lower limb (disorder)

  • <Type of> burn (disorder) (50 concepts):

    • 426284001 | Chemical burn (disorder)

    • 405571006 | Electrical burn (disorder)

    • 425656005 | Radiation burn (disorder)

    • 314534006 | Thermal burn (disorder)

  • <Depth of> burn (disorder) (575 concepts):

    • 403190006 | First degree burn (disorder)

    • 403191005 | Second degree burn (disorder)

    • 403192003 | Third degree burn (disorder)

Burn of <body structure>: This content has consistent naming conventions and modeling patterns, and Section 6.1.1.1 will recommend continuing these guidelines. 

<Type of> burn: There are currently 50 concepts following this pattern.  Because they comprise a small subset of total Burn (disorder) content and have their own content issues, this set of concepts will be reviewed and recommendations provided in Appendix A. 

<Depth of> burn: This set of content pertains to burn depth of skin and underlying tissues (e.g., first, second, third, and fourth degree burns) and is the most inconsistent in terms of naming conventions and modeling patterns.  Therefore, this content will be the predominant focus of this document.  The remainder of Section 3.4 will describe pertinent background information including:

  • Review of the anatomy, naming conventions, and classification of skin burns

  • Review of existing content issues related to <Depth of> burn concepts

  • Review of naming conventions and modeling patterns for existing <Depth of> burn content

3.4.3 Anatomy, naming conventions, and classification of skin burns

3.4.3.1 Anatomy of skin

As shown in the image below, the skin consists of two layers, the epidermis and dermis.  The epidermis has no vasculature and depends entirely on the dermis for nutrition.  The dermis is comprised of two layers: 1) the papillary layer, consisting of capillaries, elastic fibers, and collagen; and 2) the reticular layer, consisting of thicker connective tissue, larger blood vessels, hair follicles, sebaceous glands, and sweat glands.  The skin rests on a layer of subcutaneous tissue, which then covers deeper structures such as muscles, bones, and joints.  (Amirlak & Shahabi, 2015)

Image source: Shiland, 2015

3.4.3.2 Naming conventions and classification of skin burns

The naming and classification of skin burn injuries is generally based on the depth of the injury.  Burn depth is a significant determinant of mortality and the primary determinant of the patient’s long-term appearance and functional outcome. It is also a primary determinant of whether a burn will heal spontaneously or will require medical or surgical intervention. (American Burn Association, 2009)

Most authoritative references agree that there are at least three levels of burn depth corresponding to the layers of skin and subcutaneous tissues.  The traditional classification of burns as first, second, or third degree injuries is still in common use.  However, among authoritative organizations, the naming conventions appear to be evolving into more descriptive terminology: superficial, partial thickness (subdivided into superficial and deep subtypes), or full thickness burns.  Kearns et al. performed a literature review of over 1000 academic publications to evaluate the use of burn depth terminology.  They found that both numeric and descriptive terminologies were used, but that the use of descriptive terms was considerably greater than the use of numeric terms. (Kearns, Holmes, & Cairns, 2013)

Both types of naming conventions are listed and defined in the table below.  Note that these definitions are somewhat generalized, since clinically it is often difficult to estimate the depth of a burn injury and because most burn injuries consist of multiple areas with different depths of tissue involvement.  

Skin burn depth definitions

Numeric term

Descriptive term

Definition

First degree

Epidermal

(Superficial)

Depth of burn is limited to the epidermis

Second degree

Partial thickness

  •  

    • Superficial

    • Deep

Depth of burn involves the epidermis and dermis

  •  

    • Superficial: Injury is limited to the papillary layer of the dermis

    • Deep: Injury involves the reticular layer of the dermis

Third degree

Full thickness

Depth of burn involves the epidermis and dermis, and extends into the subcutaneous tissue

Fourth degree

Deep full thickness

Depth of burn extends into structures underlying subcutaneous tissue, such as muscles, joints, and bones

 

The table below lists the naming conventions and classification of skin burns described by some authoritative references.  The organization’s primary naming convention is provided first, and if the organization has a secondary or tertiary accepted convention, it is provided in brackets.  Note that there are some discrepancies.

  • Some major burn authorities support the designation of fourth degree burns while others do not.  As of March 2016, WHO ICD-11 Beta lists several codes for “Deep full thickness or complex burn of <body structure>,” suggesting that this category of burn depth will be recognized in the forthcoming edition of ICD-11.  

  • Most organizations concur that there are two types of second degree burns, though the Australia and New Zealand Burn Association has categorized this level into three subtypes. 

  • WHO ICD-9 and ICD-10 also classify “corrosions” (chemical burns) into first, second, or third degree burns. This content is inconsistently represented and is addressed in Appendix A. 

Skin burn injury naming conventions and classifications

Source

First degree

Second degree

Third degree

Fourth degree

WHO ICD-9

Erythema

[First degree]

Blisters, epidermal loss [Second degree]

1) Full-thickness skin loss [Third degree]

2) Deep necrosis of underlying tissues [Deep third degree]

 

WHO ICD-10

First degree [Erythema]

Second degree

[Blister]

[Epidermal loss]

Third degree

[Deep necrosis of underlying tissue]

[Full-thickness skin loss]

 

WHO ICD-11 Beta

(March 2016)

Epidermal

1) Superficial partial thickness

2) Deep partial thickness

Full thickness

Deep full thickness or complex

British Burn Association

 

Epidermal

Partial thickness

1) Superficial partial thickness

2) Deep partial thickness

Full thickness

Full thickness +

Australia and New Zealand Burn Association

Epidermal

1) Superficial dermal

2) Mid dermal

3) Deep dermal

Full thickness

 

American Burn Association

Epidermal

[First degree] [Superficial]

Partial thickness

[Second degree]

1) Superficial

2) Deep

Full thickness

[Third degree]

Deep full thickness

[Fourth degree]

 

 

Based on the information provided above, Section 6 will recommend that SNOMED CT burn content use the descriptive terminology (superficial, partial thickness, full thickness, and deep full thickness) as the primary convention and the numeric terminology (first, second, third, and fourth degree) as a secondary convention.  

3.4.4 <Depth of> burn concepts: existing content issues

The primary content issues which pertain to <Depth of> burn content include:

  • Inconsistent and ambiguous naming conventions (reviewed in Section 3.4.5)

  • Inconsistent modeling patterns, causing insufficient or incorrect classification (reviewed in Section 3.4.5)

  • The application of skin burn injury terminology to non-skin body structures (reviewed below)   

As previously stated, first, second, third, and fourth degree burn terminology applies to burns of skin and underlying tissues.  However, for approximately 45 existing concepts, this terminology has been applied to burns of non-skin body structures.  For example:

  • 110192005 | Second degree burn of buccal mucosa (disorder)

  • 110235001 | Second degree burn of tongue (disorder)

  • 284199004 | Partial thickness burn of eye (disorder)

  • 110217005 | Third degree burn of floor of mouth (disorder)

  • 110221003 | Third degree burn of hard palate (disorder)

These concepts present challenges for a few reasons:

  • The meaning of these concepts is ambiguous.  The unique histology of these body structures does not necessarily correlate with that of skin and deeper tissue structures, therefore, it is unclear what first, second, or third degree burns of these body structures actually mean.

  • There are separate authoritative burn classification systems for some non-skin body structures that utilize distinct terminology and definitions (e.g., classification systems for burns of the eye, gastrointestinal tract, and respiratory tract).  The use of skin burn terminology for these structures may result in a different meaning.  For example, a Roper-Hall Grade II ocular surface burn has a specific definition which may not be conveyed by the existing concept 284199004 | Partial thickness burn of eye (disorder).

  • Naming and modeling burns of non-skin body structures by skin burn terminology results in compromises to concept definitions for concepts that do represent skin structures.  For example, first and second degree burns are both burns of skin, but currently, First degree burn (disorder) is a subtype of Burn of skin (disorder) while Second degree burn (disorder) is not.  As will be described in the next section, this difference is due to differences in modeling which impact the grouper concept Second degree burn (disorder) and many of its subtypes.

The list of relevant concepts as well as references for authoritative burn classifications for some non-skin body structures is provided in Appendix B and addressed further in Section 6.1.1.2.1.

3.4.5 <Depth of> burn concepts: existing naming conventions and modeling patterns

This section will focus on <Depth of> burn content naming conventions and modeling patterns.  The concept numbers provided are current as of the January 2016 SNOMED CT International Release. 

3.4.5.1 Overview

The table below provides an overview of existing Burn (disorder) content:  

Burn (disorder) hierarchy concepts

Number of concepts

Burn of <body structure> (disorder)

214

<Type of> burn (disorder)

Chemical burn (disorder)

Thermal burn (disorder)

Electrical burn (disorder)

Radiation burn (disorder)

50

24

23

3

1

<Depth of> burn (disorder)

First degree burn content

Second degree burn content

Third degree burn content (Includes Fourth degree burn content)

575

110

163

302

Total

839

 

3.4.5.2 First degree burn content

Naming conventions

There are currently 110 concepts referencing first degree burn disorders.  As noted in the sections above, SNOMED CT has burn injury content originating from multiple sources, resulting in a mix of terminology for this content.  Also, the terms “burn erythema” and “corrosion” (chemical burn) are only found in WHO ICD-9 and ICD-10.  The preferred terminology for this content is 1) Epidermal burn and 2) First degree burn.  The table below lists all of the various terms currently used to represent first degree burns in Fully Specified Names (FSN) of existing concepts. 

Term in FSN

Number of concepts

Epidermal burn

8

First degree burn

5

Superficial burn

17

Burn erythema

60

Corrosion of first degree

7

Superficial corrosion

13

Total

110

 

Modeling patterns

Because first degree burns involve the epidermis layer of the skin, First degree burn (disorder) is appropriately a subtype of Burn of skin (disorder).  There are 75 First degree burn (disorder) concepts which are modeled and classify appropriately.  However, there are 35 concepts which have naming conventions consistent with first degree burns, but do not classify as subtypes of First degree burn (disorder).  Of these 35 concepts, 13 concepts reference first degree burns of non-skin body structures.  These “missed inferences” are actually correct: since these concepts do not represent burns of skin, they should not be subtypes of Burn of skin (disorder).  The lists of concepts with skin burn terminology applied to non-skin body structures is provided and addressed in Appendix B.  Additional concepts with modeling issues indicated in the table below are provided in Appendix C.

Query

Concepts

Total number of First degree burn (disorder) concepts

75

Total number of concepts with naming conventions consistent with first degree burns, but do not classify as subtypes of First degree burn (disorder):

Concepts not modeled with a FINDING SITE value of <skin structure> (19)

Concept with appropriate attribute-value pairs, but not role grouped (1)

Concepts referencing first degree burns of non-skin body structures (13)

Concepts not modeled with ASSOCIATED MORPHOLOGY: First degree burn injury (morphologic abnormality) (2)

35

Total

110

 

3.4.5.3 Second degree burn content

Naming conventions

There are currently 163 concepts referencing second degree burn disorders.  Similar to first degree burn content, there is a mix of terminology used to represent second degree burn content.  The term “burn blister” is only found in WHO ICD-9 and ICD-10.  The preferred terminology for this content is 1) Partial thickness burn (divided into Superficial and Deep) and 2) Second degree burn.  The table below lists all of the various terms currently used to represent second degree burns in existing concepts.  

Term in FSN

Number of concepts

Partial thickness burn

20

Superficial partial thickness burn

35

Deep partial thickness burn

35

Second degree burn

64

Burn blister

2

Corrosion of second degree

7

Total

163

 

Modeling patterns

Second degree burns refer to burns of the dermis layer of the skin.  However, Second degree burn (disorder) is not a subtype of Burn of skin (disorder), because it is not modeled with a FINDING SITE value of <skin structure>.  There are two important consequences of this modeling pattern:

  • Even though Second degree burn (disorder) is not a subtype of Burn of skin (disorder), approximately 130 of its descendants are subtypes of Burn of skin (disorder) because they are modeled with a FINDING SITE attribute value of <skin structure>.  There are a total of 17 concepts referring to second degree burns which do not have a FINDING SITE value of <skin structure>.  These concepts are provided in Appendix C.

  • All concepts modeled with an ASSOCIATED MORPHOLOGY value of Second degree burn injury (morphologic abnormality) classify as subtypes of Second degree burn (disorder), including 16 concepts that reference second degree burns of non-skin body structures.  These concepts are listed and addressed in Appendix B. 

Query

Concepts

Total number of Second degree burn (disorder) concepts

161

Total number of concepts with naming conventions consistent with second degree burns, but do not classify as subtypes of Second degree burn (disorder)

2

Total

163

 

3.4.5.4 Third and fourth degree burn content

Third and fourth degree burn content are addressed together because this content is currently intermixed in SNOMED CT.  Fourth degree burn content (Deep full thickness burn (disorder)) is a subtype of third degree burn content (Third degree burn (disorder)).  In addition, there are concepts referencing “deep third degree burns” (a term found only in ICD-9) which are both subtypes of and descriptions for concepts referring to fourth degree burns.

Naming conventions

There are currently 302 concepts referencing third or fourth degree burn disorders.  As shown below in the table below, there is a mix of terminology used to represent this content, and terms such as “deep third degree burn” and “deep necrosis” are only found in ICD-9 and/or ICD-10.  The preferred terminology for third degree burn content is 1) Full thickness burn and 2) Third degree burn.   The preferred terminology for fourth degree burn content is 1) Deep full thickness burn and 2) Fourth degree burn.  The table below lists all of the various terms currently used to represent third and fourth degree burns in existing concepts.

Term in FSN

Number of concepts

Third degree burn content

 

Full thickness burn

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