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Gloss
tSNOMED CT
can be implemented in a wide range of clinical record applications. These include systems developed for use with other code systems that have been adapted to support
Gloss
tSNOMED CT
as well as systems designed with the assumption that
Gloss
tSNOMED CT
would serve as the primary terminology. The
Gloss
tSNOMED CT
features that applications support and use may vary, partly due to differences in user requirements and partly due to development priorities. Against this background of variability, it is reasonable to ask what is a
Gloss
tSNOMED CT implementation
or what is a good
Gloss
tSNOMED CT implementation
. While there is not a single or simple answer to these questions, this section identifies some key dimensions which determine the capability of
Gloss
tSNOMED CT
enabled clinical record systems.

Each of the following sections describes a dimension and outlines a spectrum of capabilities ranging from absence of support (Level 0) to full support (Level 2). A mixture of Level 0 and Level 1 capabilities are likely to be found in existing systems that have been adapted to work with

Gloss
tSNOMED CT
. A system specifically developed to work with
Gloss
tSNOMED CT
should be expected to have capabilities that are at least at the high end of the Level 1 spectrum and should ideally have Level 2 capabilities.

The specification of different levels is not intended to suggest a step-by-step development path. Those needing to rapidly

Gloss
tSNOMED CT
enable an existing clinical record system are recommended to follow a two stage approach.

  1. Anchor
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    Design, develop and deploy a revision to the current system to support Level 1 capabilities that meet known short or medium term requirements:
    Anchor
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    • The level achieved in this stage will depend on customer requirements and the design limitation of the existing system.
  2. Design and develop a new or substantially revised system (including revised record structures) to support a mixture of high-end Level 1 and Level 2 capabilities:
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    • The level at which this development is target should be one that meets anticipated medium to long term requirements;
    • Even if the initial target of the work is limited to the high-end of Level 1, the design should be sufficiently flexible to enable Level 2 capabilities to be added when required.

Developers who do not require a rapid deployment based on a revision of an existing systems are recommended to skip the first step and proceed to design and develop a flexible solution that utilizes the key strengths of

Gloss
tSNOMED CT
.

Each of the following sections describes one dimension that contributes to the overall implementation level. It is important to recognize that:

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  • This is not a formal scoring scheme:
    Anchor
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    • Some dimensions are more significant than others;
    • The significance of reaching a particular level depends on the nature of the application and the user requirements it seeks to address.
  • Many of the dimensions are inherently interdependent:
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    • For example, Level 2 data entry capabilities are not compatible with Level 1 data storage.

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Implementation Level - Scope of use

A clinical record system may use

Gloss
tSNOMED CT expressions
to represent some or all of the types of information outlined in the list below. The types of information for which
Gloss
tSNOMED CT
can be used may be limited by the structure used to store the
Gloss
telectronic health record
. The significance of these limitations depends upon the intended use of the clinical record system.

  • Level 0: No support for
    Gloss
    tSNOMED CT expressions
    .
  • Level 1: Support for use of
    Gloss
    tSNOMED CT
    limited to particular types of clinical data:
    • Addressing the requirements for a particular type of use;
    • Addressing a set of requirements specified by a particular organization .
  • Level 2: Support for consistent use of
    Gloss
    tSNOMED CT
    across a broad scope of information types:
    • Providing a general purpose approach to the use of
      Gloss
      tSNOMED CT
      within an
      Gloss
      telectronic health record
    • Allowing configuration to vary the scope of coverage to meet specific requirements.

The following check-list identifies some of the

Gloss
telectronic health record
elements in which
Gloss
tSNOMED CT expressions
might be used. The list is not complete but it covers many of the areas in which use of
Gloss
tSNOMED CT
has been discussed in
Gloss
tSNOMED International
working groups. It is intended to assist consideration of the areas in which
Gloss
tSNOMED CT
should be used to meet the needs of users and organizations. The inclusion of an item in this list does not imply that the
Gloss
tSNOMED CT International Release
provides comprehensive content to populate that part of the record.

  1. Anchor
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    Disorders, diagnoses and problems:
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    • Problem list entries;
    • Admission diagnosis;
    • Discharge diagnosis;
    • Provisional or working diagnosis;
    • Differential diagnosis.
  2. Symptoms:
    • Presenting symptoms;
    • History of current condition;
    • Other symptoms.
  3. Allergies and adverse reactions:
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    • Adverse reaction events;
    • Allergies and other propensities to adverse reactions.
  4. Procedures:
    • Operative procedures.
    • Diagnostic procedures.
    • Medications:
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      • Current medication;
      • Prescriptions;
      • Dispensing records;
      • Drug charts.
    • Other therapeutic procedures:
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      • Other therapy requests;
      • Other therapy delivery and outcomes.
  5. History:
    • Medical and surgical past history;
    • Medication history;
    • Family history.
  6. Examination findings:
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    • Vital signs;
    • Clinical examination findings.
  7. Investigation information:
    • Laboratory investigations:
      • Laboratory investigation requests;
      • Laboratory investigation procedures;
      • Laboratory investigation results.
    • Diagnostic imaging:
      • Diagnostic imaging requests;
      • Diagnostic imaging procedures;
      • Diagnostic imaging results.
    • Other investigations:
      • Other investigation requests;
      • Other investigation procedures;
      • Other investigation result.
  8. Other types of clinical information:
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    • Planned actions;
    • Risk, goal and expected outcomes;
    • Scale based assessments;
    • Progress notes.
  9. Administrative information:
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    • Admission, transfer and discharge events.
  10. Other values:
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    • Body sites, structures and locations;
    • Organisms;
    • Substances (other than drugs);
    • Pharmaceutical and biological products (drugs).

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Implementation Level - Record structure

The logical model underlying the structure of the record has a direct effect on the ability of a

Gloss
tSNOMED CT
enabled clinical record system to take advantage of the features of
Gloss
tSNOMED CT
. An application may use an optimized proprietary internal representation of the
Gloss
telectronic health record
. However, consistent use of
Gloss
tSNOMED CT
across a range of applications requires a common reference model to which proprietary structures are mapped. In addition to this, the ways in which
Gloss
tSNOMED CT expressions
are used within a common
Gloss
treference information model
need to be constrained to improve predictability and minimize ambiguity.

  • Level 0: A proprietary structure that is neither aligned with nor mapped to a standard
    Gloss
    treference information model
    :
    • Low: Text only record with no use of clinical codes;
    • High: Structured record supporting use of clinical codes.
  • Level 1: A structure that is aligned with or mapped to a standard
    Gloss
    treference information model
    :
    Anchor
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    • Low: Proprietary structure mapped to a standard model to support limited messaging requirements. Supports the use of
      Gloss
      tSNOMED CT
      coding within that structure.
    • High: Structure aligned with a standard
      Gloss
      treference information model
      that supports that supports use of
      Gloss
      tSNOMED CT
      coding.
    • Examples of standard
      Gloss
      treference information models
      include:
      Anchor
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      _8b6d88a7-b1c3-479b-9c8f-456f80206b7d__9
      • The
        Gloss
        tHL7
        Version 3
        Gloss
        tReference Information Model
        (RIM);
      • The
        Gloss
        tCEN TC251
        Health informatics -
        Gloss
        tElectronic health record
        communication - Part 1: Reference model (
        Gloss
        tEN13606
        ).
  • Level 2: An aligned or mapped structure in which
    Gloss
    tSNOMED CT expressions
    are used in accordance with agreed guidelines for use of a standard
    Gloss
    treference information model
    :
    Anchor
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    • In Level 2
      Gloss
      tSNOMED CT
      is used in accordance with
      Gloss
      tterminology binding
      guidance to minimize the semantic gaps and overlaps between the terminology and the information model. Without constraints, these gaps and overlaps lead to inconsistent representation of similar data and thus limit the effective reuse of information.
    • Example of agreed guidelines for using use of
      Gloss
      tSNOMED CT expression
      in particular reference models include:
      Anchor
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      • The
        Gloss
        tHL7TermInfo
        DSTU - Guide to the Use of
        Gloss
        tSNOMED CT
        in
        Gloss
        tHL7
        Version 3;
      • Guidance on
        Gloss
        tterminology binding
        developed by the
        Gloss
        tUK NHS
        Logical Record Architecture for use in an
        Gloss
        tEN13606
        based logical model.

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Implementation Level - Expression storage

Support for storing

Gloss
tprecoordinated
and
Gloss
Spacetrue
tpostcoordinated
Gloss
tSNOMED CT expressions
determines the extent to which
Gloss
tSNOMED CT
can be used to represent detailed information within an
Gloss
telectronic health record
.

  • Level 0: No support for storage of
    Gloss
    tSNOMED CT expressions
  • Level 1: Support for storage of
    Gloss
    Spacetrue
    tprecoordinated
    Gloss
    tSNOMED CT expressions
    :
    Anchor
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    • Support for storage of a
      Gloss
      tprecoordinated expression
      implies the ability to store a representation of a
      Gloss
      tconcept identifier
      as part of each item for which
      Gloss
      tSNOMED CT
      is used:
      Anchor
      _83b41d37-9666-4a92-a163-a03f39ab41d1__1
      _83b41d37-9666-4a92-a163-a03f39ab41d1__1
      • The
        Gloss
        tconcept identifier
        may be represented as a 64-bit
        Specref
        RefTypedata type
        tInteger
        or as an 18-digit string ;
      • Other internal representations may be used provided they can be resolved to the appropriate
        Gloss
        tIdentifier
        for display, communication or processing.
  • Level 2: Support for storage of
    Gloss
    Spacetrue
    tpostcoordinated
    Gloss
    tSNOMED CT expressions
    :
    Anchor
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    _83b41d37-9666-4a92-a163-a03f39ab41d1__2
    • Support for storage of
      Gloss
      tpostcoordinated expression
      implies the ability to store a representation that captures the logical model of a
      Gloss
      tpostcoordinated expression
      :
      • The simplest representation of a
        Gloss
        tpostcoordinated expression
        is the
        Gloss
        tSNOMED CT compositional grammar
        . Due to the open-ended nature of
        Gloss
        tpostcoordinated expressions
        , this representation results in a string of variable length with no clear-cut maximum length.
      • The guide discusses alternative representations including the use of
        Gloss
        texpression
        reference table which enables use of a fixed length reference within the records. This approach uses a UUID which can be represented as a 128-bit
        Specref
        RefTypedata type
        tInteger
        or as a hexadecimal string (see Storing expressions ) .
    • This level has variants depending on the extent of support for
      Gloss
      tpostcoordinated expression
      storage:
      Anchor
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      • Low: Storage of
        Gloss
        tpostcoordinated expressions
        limited to specific fields in the record structure;
      • High: Full support for storage of
        Gloss
        tpostcoordinated expression
        allowing any valid
        Gloss
        texpression
        to be stored and retrieved.

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Implementation Level - Data entry

The categorization in this section in based on the extent to which the system enables entry of

Gloss
tSNOMED CT expressions
. In addition, this section indicates the importance of a well-designed user-interface.

  • Level 0: No support for entry of
    Gloss
    tSNOMED CT expressions
    .

.

  • Level 1: Support for
    Gloss
    Spacetrue
    tprecoordinated
    Gloss
    tSNOMED CT expression
    entry:
    Anchor
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    _51c1d64a-8ab6-43ad-93f0-fde5daf99bab__3
    • Low: Access limited to fixed set of
      Gloss
      tSNOMED CT concepts
      ;
    • Medium: Access to full content of
      Gloss
      tSNOMED CT
      ;
    • High: Access to full content of
      Gloss
      tSNOMED CT
      with configurable
      Gloss
      tvalue sets
      matched to user requirements.
  • Level 2: Support for
    Gloss
    tpostcoordinated expression
    entry:
    Anchor
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    • Low: Access to limited
      Gloss
      tpostcoordination
      (matching data storage restrictions);
    • Medium: Access to full range of
      Gloss
      tpostcoordination
      supported by the
      Gloss
      tConcept Model
      ;
    • High: Access to
      Gloss
      tpostcoordination
      with configurable
      Gloss
      tconstraint
      matched to user requirements.

Another important data entry issue is the ease of use which depends on the usability, relevance and performance of searches. Where

Gloss
tpostcoordinated
data entry is supported the approach to selecting or constructing
Gloss
tpostcoordinated expressions
is also significant.

An attempt to categorize specific approaches to the user-interface is subjective as alternative

Gloss
tuser interfaces
may be appropriate to different uses. However, for most environments a flexible range of configurable
Gloss
tSNOMED CT
aware user-interface tools is likely to offer a better user experience than reliance on a one-size fits all
Gloss
tbrowser
or search engine.

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Implementation Level - Data retrieval

A major strength of

Gloss
tSNOMED CT
is its ability to support meaning based selective retrieval. The extent to which this feature is used by a clinical record system determines the value of entering and storing the data.

  • Level 0: No native support for
    Gloss
    tSNOMED CT
    enabled data retrieval:
    Anchor
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    • This level has variants depending on whether it can map code in exported data to
      Gloss
      tSNOMED CT expressions
      :
      Anchor
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      • Low: No support for
        Gloss
        tSNOMED CT
        based analysis;
      • High: Support for extracting a specified set of locally coded data and mapping the local codes to appropriate
        Gloss
        tSNOMED CT expression
        for central aggregation and analysis.
  • Level 1: Support for retrieval of
    Gloss
    Spacetrue
    tprecoordinated
    Gloss
    tSNOMED CT expressions
    :
    Anchor
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    • This level has a spectrum of variants depending on the level of support for the following features:
      Anchor
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      • Query expressivity: The ability to express
        Specref
        RefTypefield
        tquery
        predicates that explicitly include or exclude
        Gloss
        tsubtypes
        of specifically identified
        Gloss
        tconcepts
        ;
      • Subsumption testing: Use of
        Gloss
        Spacetrue
        tSNOMED CT
        Gloss
        tsubtype hierarchy
        to interpret and evaluate queries;
      • Gloss
        tConcept Equivalence
        : The ability to retrieve equivalent information even if it is represented in different structures within the record;
      • Context awareness: The ability to take account of contextual information, derived from the record structure and/or the
        Gloss
        Spacetrue
        tSNOMED
        Gloss
        texpression
        , when interpreting and evaluating queries;
      • Performance: The ability to interpret and evaluate queries within an appropriate period of time and without causing deterioration in other system functions.
  • Level 2: Support for retrieval of
    Gloss
    Spacetrue
    tpostcoordinated
    Gloss
    tSNOMED CT expressions
    :
    Anchor
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    • This level has a spectrum of variants depending on the level of support for the following additional aspects of the features specified for Level 1:
      Anchor
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      • Query expressivity: The ability to represent
        Gloss
        tpostcoordinated
        predicates in a
        Specref
        RefTypefield
        tquery
        ;
      • Subsumption testing: Use of
        Gloss
        tdefining characteristics
        and
        Gloss
        tnormal form transformations
        (or a
        Gloss
        tdescription logic classifier
        ) to determine whether
        Gloss
        texpressions
        are subsumed by
        Specref
        RefTypefield
        tquery
        predicates;
      • Gloss
        tEquivalence
        : Use of
        Gloss
        tdefining characteristics
        and
        Gloss
        tnormal form transformations
        (or a
        Gloss
        tdescription logic classifier
        ) to determine
        Gloss
        tequivalence
        between different
        Gloss
        tpostcoordinated expressions
        and in different structures within the record;
      • Context awareness: The ability to take account of contextual information derived from the record structure and/or
        Gloss
        Spacetrue
        tpostcoordinated
        Gloss
        Spacetrue
        tSNOMED
        Gloss
        texpressions
        , when interpreting and evaluating queries;
      • Performance: The ability to interpret and evaluate queries that support
        Gloss
        tpostcoordinated
        representations within an appropriate period of time and without causing deterioration in other system functions.

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Implementation Level - Communication

The ability to send and received

Gloss
tSNOMED CT expressions
in messages or other communication is partially dependent on data entry, storage and retrieval capabilities. However, some types of communication may be supported by mapping or human-readable renderings even in the absence of internal support for
Gloss
tSNOMED CT
.

  • Anchor
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    Level 0: Mapping based support for communication of
    Gloss
    tSNOMED CT expressions
    :
    • Inbound communications containing
      Gloss
      tSNOMED CT expressions
      :
      Anchor
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      _c0528298-1f3b-4abc-b965-97db5ade147d__7
      • Low: Not supported.
      • Medium: Rendered as human-readable text. Unless the inbound message also contains the
        Specref
        RefTypefield
        tterm
        text, this requires access to some
        Gloss
        tSNOMED CT
        enable
        Gloss
        tTerminology services
        to lookup and display the relevant
        Specref
        RefTypefield
        tterm
        .
      • High: Mapped to an internal coding scheme or classification. This may be feasible to support specific use cases but not for the full scope of clinical information.
    • Outbound communication containing
      Gloss
      tSNOMED CT expressions
      :
      • Low: Not supported;
      • Medium: Supported for a few specific types of clinical data in the existing system by mapping to from an existing code system to
        Gloss
        tSNOMED CT
        ;
      • High: Supported for most clinical data in the existing system by mapping to from an existing code system to
        Gloss
        tSNOMED CT
        .
  • Level 1: Native support for communication of
    Gloss
    Spacetrue
    tprecoordinated
    Gloss
    tSNOMED CT expressions
    :
    • Inbound communications containing
      Gloss
      Spacetrue
      tprecoordinated
      Gloss
      tSNOMED CT expressions
      :
      • Low: Supported for some types of information but constrained by data entry and
        Gloss
        texpression
        storage capabilities;
      • High: Supported for most types of information.
    • Outbound communications containing
      Gloss
      Spacetrue
      tprecoordinated
      Gloss
      tSNOMED CT expressions
      :
      Anchor
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      _c0528298-1f3b-4abc-b965-97db5ade147d__6
      • Low: Supported but limited by data entry and storage and retrieval capabilities;
      • High: Supported for most types of information.
  • Level 2: Native support for communication of
    Gloss
    Spacetrue
    tpostcoordinated
    Gloss
    tSNOMED CT expressions
    :
    Anchor
    _c0528298-1f3b-4abc-b965-97db5ade147d__e
    _c0528298-1f3b-4abc-b965-97db5ade147d__e
    • Inbound communications containing
      Gloss
      Spacetrue
      tpostcoordinated
      Gloss
      tSNOMED CT expressions
      :
      • Low: Support limited to particular attributes (e.g. |laterality|, |causative agent|) in
        Gloss
        tpostcoordinated expression
        ;
      • Medium: Support for general
        Gloss
        tpostcoordination
        applied to some types of information;
      • High: Able to receive, process and store any valid
        Gloss
        tpostcoordinated expression
        .
    • Outbound communications containing
      Gloss
      Spacetrue
      tpostcoordinated
      Gloss
      tSNOMED CT expressions
      :
      Anchor
      _c0528298-1f3b-4abc-b965-97db5ade147d__3
      _c0528298-1f3b-4abc-b965-97db5ade147d__3
      • Low: Support limited to particular attributes (e.g. |laterality|, |causative agent|) in
        Gloss
        tpostcoordinated expression
        ;
      • Medium: Support for outbound communication of any
        Gloss
        tpostcoordinated expression
        that can be entered or stored in the system;
      • High: Support for outbound communication of any valid
        Gloss
        tpostcoordinated expression
        .