SNOMED CT

Basic principles underlying the SNOMED CT Structure

* SNOMED CT is concept-based * each concept represents a unit of meaning * each concept has 1 or more human language terms that can be used to describe the concept * every concept has interrelationships with other concepts that provide, logical computer readable definitions

Examples of cross maps

* SNOMED CT to ICD-9-CM * SNOMED CT to ICD-10 * SNOMED CT to ICD-10-CM * SNOMED CT to office of population censuses and surveys classification of interventions and procedures

SNOMED-CT Purposes

* capture clinical data at the appropriate level of detail * minimize the need for repetitive data entry at varying levels of granularity * reduce the risk of different interpretations via unambiguous descriptions * facilitate communication among care providers * retrieve, transmit, and analyze data consistently * facilitate continuity of care * reduce repetition across the continuum of care * enable efficient searching * facilitate point of care decision support * allow application of logical processing

Main SNOMED CT Components

* concepts * descriptions * relationships

basic structural elements

* concepts * hierarchies * descriptions * relationships

Aggregation, analysis of clinical information benefit

* enables decision support at the point of care for individual cases * enables population-based aggregation and analysis of clinical information

derivative works in SNOMED CT

* reference sets (RefSets) * cross maps * other resources

index, retrieve clinical data benefit

* retrieves clinical statements according to their meaning, at various levels of abstraction * provides for semantic interoperability, i.e. the ability of computer systems to interchange data and to interpret and use the data according to its meaning, rather than just its surface form * provides a mechanism to build applications capable of encoding clinical data to permit meaningful retrieval. The unambiguous descriptions of individual concepts in SNOMED CT are consistent and logical, allowing logical processing and machine reasoning of clinical information

URU principle

* understandable: the meaning must be able to be communicated in a manner that can be understood by an average healthcare provider without reference to inaccessible, hidden or private meanings * Reproducible: it isn't enough for 1 individual to say they understand a meaning. It must be shown that multiple people understand and use the meaning in the same way * Useful: the meaning must have some demonstrable use or applicability to health or healthcare

SNOMED CT Core subset data file

*SNOMED_CID * SNOMED_FSN * SNOMED_CONCEPT_STATUS * UMLS_CUI * OCCURRENCE * USAGE * FIRST_IN_SUBSET * IS_RETIRED_FROM_SUBSET * LAST_IN_SUBSET * REPLACED_BY_SNOMED_CID

Encode, store clinical data benefit

*allows precise recording of clinical information. By using many descriptions for a single clinical concept, SNOMED CT allows tailoring for individual care settings while maintaining consistency * represents health information to support clinical care by encoding statements about the health and health care of an individual patient, without forcing arbitrary categories * Enhances communication between clinicians through consistent and controlled terminology

SNOMED CT

A comprehensive clinical terminology that provides clinical content and expressivity for clinical documentation and reporting

SNOMED CT identifier

A unique identifier assigned to each SNOMED CT component

Computer-based patient record institute (CPRI)

Determined that SNOMED was the most comprehensive controlled terminology for coding the contents of the patient record and facilitating the development of computerized patient records

SNOMED-CT (Systematized Nomenclature of Medicine Clinical Terms)

Embedded in the EHR system and works behind the scenes to identify the clinical concepts in the health record in machine-readable format

Cross maps

Enable SNOMED CT to effectively reference other terminologies and classifications. Each one matches SNOMED CT concepts with values in another coding scheme that is called the "target scheme." Links a single SNOMED CT concept to one or more values in a target coding scheme, the concept may have a single or a set of alternatives.

causative agent and finding site attribute relationship

Figure 6.2 illustrates not only | is a | relationships but also the causative agent and finding site attribute relationships. The graph indicates that for every instance of bacterial pneumonia, there is a causative agent relationship to particular bacteria and likewise for bacterial pneumonia there is a finding site of lung structure. SNOMED CT description logic definitions put these together to define bacterial pneumonia as an infective pneumonia with causative agent bacteria and the lung structure as the finding site. Thus the combination of applicable SNOMED CT defining relationships provides a computer-readable definition of a concept.

CORE Problem list Subset

Identifies concepts most useful for documentation and encoding of clinical information at the summary level, such as problem list, discharge diagnosis, or reason for the encounter

Preferred term (PT)

In SNOMED CT, the description or name assigned to a concept that is used most commonly; in the UMNDS classification system, a representation of the generic product category, which is a list of preferred concepts that name devices

Fully specified name (FSN)

In SNOMED CT, the unique text assigned to a concept that completely describes that concept

REPLACED_BY_SNOMED_CID

SNOMED CT concept to replace concept retired from subset, only populated for concepts retired from subset

Relationships

These link each concept to other concepts with a related meaning. They provide formal definitions and other characteristics of the concept. Each SNOMED CT concept has at least 1 to another concept

SNOMED CT revision and update

Twice yearly Each includes updated to the core (concepts, descriptions, relationships) as well as derivative works and related documentation

controlled medical terminology

a restricted vocab of medical concepts and expressions used in healthcare

extension mechanism

a structure that enables authorized organizations to add concepts, descriptions, relationships, and subsets to complement the SNOMED CT international release

Concepts structure

according to logic-based representation of meanings. Each code is represented by a node in the graph, and each relationship is represented by an arrow

concepts

basic unit of SNOMED CT and defined as unique knowledge created by a unique combination of characteristics

Implementation and education committee

charged with providing advice and assistance which enables the implementation of SNOMED CT through software applications such that clinical info can be managed and clinical decision making assisted

SNOMED_CID

conceptId of the SNOMED CT concept

Concept orientation

concepts are based on meanings and not words

Subset RefSet

contains included and excluded component form the set of values that can be used n a particular country, organization, specialty, or context

SNOMED CT Clinical concepts

cover disorders, findings, procedures, body structures, pharmacy products, and others that encompass all of healthcare

Reference sets (RefSets)

defined groups of SNOMED CT Components. They can be a simple list of concepts or a group of subsets that go together. They can also be tagged to denote the type of group or use. The contents may overlap with others

Attribute relationship

defining relationships where specialization may be added to a concept to make its meaning more detailed. For example, the attribute relationships for the concept bacterial pneumonia shown in figure 6.2 are finding site (the name of the type of relationship), lung structure (the value or destination of the relationship), causative agent (the name of the type of relationship) and bacteria (the value or destination of the relationship). Application of the type attribute relationships is limited to a defined domain and range (IHTSDO 2014a). For example, the allowed attributes for Anatomical structure (body structure) are | laterality | and | part of | and the allowable ranges for | finding site | is | Anatomical or acquired body structure | 442083009

description identifier

each description is assigned a unique number, and is always attached to a specific concept. There may be varying descriptions for each concept, and each gets it's own number

SNOMED CT Route of administration subset

exists to facilitate the use of SNOMED CT as the primary terminology for documentation and encoding of clinical information regarding substance administrations. In addition, a portion can be used in the drug listening section of structured product labeling

technical committee

focuses on advising on all issues related to the technical framework and technology platform required for the development, maintenance and implementation of SNOMED CT and its related standards and specifications

SNOMED_FSN

fully-specified name

the General Assembly (GA)

highest authority of the IHTSDO; responsible for assuring purpose, objects, and principles are pursued and interests are safeguarded

Extension components

identified using an item identifier of 1-8 digits and a 7 digit namespaced identifier

concept permanence

identifiers that represent the concept are not reused and thus meanings do not change

language RefSet

identifies characteristics of terms according to the language in which they are being used

IS_RETIRED_FROM_SUBSET

in future, some concepts will be marked retired if they are retired by IHTSDO or no longer considered to be useful, for example when there are more appropriate SNOMED CT concepts

Kaiser Permanente Current Medical Terminology (CMT) subset

includes over 75,000 clinician and patient-friendly terms used as display names for physician and patients in the electronic medical record and personal health record portal. These terms are linked to concepts in the international release of SNOMED CT and the US extension and are mapped to ICD-9-CM and ICD-10-CM

Simple and complex map RefSets

indicates associations between members of the set and content of a target coding scheme

Editorial Guide

intended for clinical personnel, business directors, software product managers, and project leaders. Explains SNOMED CT's capabilities and uses from a content perspective.

Technical Implementation Guide (TIG)

intended for software designers and assumes the reader has IT and software development experience. Contains guidelines and advice about the design of applications using SNOMED CT, and covers topics such as release file specifications, concept model, terminology servers, entering and storing info, and migration of legacy info

nursing problem list subset

intended to facilitate the use of SNOMED CT as the primary coding terminology for nursing problems used in care planning, problem lists, or other summary level nursing documentation

Starter guide

introductory overview of the content, structure, and terminology for SNOMED CT

Project groups (PGs)

limited duration and focus on a particular task and project plan

descriptions

link appropriate human-readable terms to concepts. They are the terms or text for the concept. Each concept can have several, each representing alternative text that describes the same clinical idea

special interest groups (SIGs)

may be ongoing and are focused on a particular interest, community, or topic area

OCCURRENCE

number of institutions having this concept on their problem list (from 1-8), not populated for concepts retired from subset

pre-coordination

often used to represent a commonly used clinical term as a single concept

SNOMED CT size

over 300,000 active concepts

SNOMED CT purpose

provide a consistent way of indexing, storing, retrieving, and aggregating clinical data from structured electronic health records. uniquely IDs clinical info consistently and with granularity

Navigational RefSet

removes the extra | is a | layer to allow the user to find the influenza A virus more easily

Content Committee

responsible for clinical and scientific issues related to definition and maintenance of the content and structure of SNOMED CT as well as other terminology products

Quality assurance committee

responsible for quality assurance of SNOMED CT and its related standards and other terminology products

SNOMED CT componenets

share a common characteristic such as language, specialty, user, or context and are grouped together to be used for a particular purpose

concept identifiers

string of digits with a minimum length of 6 digits and a maximum length of 18 digits, most commonly 8 or 9 digits. THese do not have embedded meaning or digit restrictions, even when the knowledge of a concept changes, this number string does not

relationship types

subtype and attribute. "| is a | relationship", this subtype relationship must always be known to be true. Concepts are always related by | is a | relationship to the concept directly above them in the hierarchy . The following | is a | relationships are represented by the arrows in figure 6.2:

USAGE

the average usage percentage among all institutions, not populated for concepts retired from subset

UMLS_CUI

the corresponding UMLS concept identified; if concept is not yet in the UMLS this will be NA

LAST_IN_SUBSET

the version of subset last containing this concept, only populated for concepts retired from subset

root concept

top of the SNOMED CT hierarchy; single special concept that represents the root of the entire content

Management board

up to 12 directors elected by the GA, responsible for the strategic direction of the organization

FIRST_IN_SUBSET

version of Subset first containing this concept

post-coordination

when a combination of concept identifiers are joined to convey clinical meaning