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Record structure standards and proposals

SNOMED CT is a controlled terminology that can be used in many different health record systems. The semantic model of SNOMED CT does not replace the need for a logically sound health record structure. Furthermore, the SNOMED International does not specify a particular health record structure for use in conjunction with SNOMED CT. However SNOMED CT representations of clinical concepts are intended to meet the needs of standard health record architectures for a consistent controlled coded terminology.

In particular, there is a strong interest in co-evolution of SNOMED CT and the following standards to provide a strong standard semantic foundation for future electronic health record development.

Using SNOMED CT in standard architectures

The broad principles of the established health record architectures are based on a layered structure of components that contain and provide context to lower level components.

The container structures include some or all of the following:

  • A top-level component representing the entire health record of one person.
  • Intermediate layers representing information from various sources.
  • A fixed transaction/composition layer at which an entry or set of entries are attributed to (and possibly signed by) an author:
    • Examples of this level include consultation notes, letters, reports, and other documents.
  • Further levels that represent logical grouping within a record covering:
    • Topics, heading and categories;
    • Cluster or batteries of closely associated information.

Within the containment structures are two lower level components:

  • Clinical statements:
    • A clinical statement may vary in structure to accommodate different kinds of information (e.g. patient history, clinical finding, investigation results, plans, procedures, medication and other therapies).
  • Link statements:
    • Link statements state associations between clinical statements.
    • Links statements can be used to specify:
      • Problem- oriented groups of record components and viewing;
      • Causal and other specified links recorded by the author of a record entry.

Each health record component has the potential to include:

  • Dates and times of actual and planned events.
  • Associations with people, organizations , devices and other entities that participate or are used in relations to a recorded event or plan.
  • Codes or other representations that name or provide the semantic information container, link, or statement:
    • SNOMED CT fulfills this role in a structured health record.
  • Additional data including text, numeric values, images and other digital data.

When SNOMED CT is used in a structured record, the links and temporal associations of components combined add further richness to the potential power of expression . This has significant advantages and is essential for many types of aggregation and decision support. However, it also adds a complicating factor that should be taken into account when designing, recording, storage, and retrieval facilities.

Example:

To retrieve and analyze the records of patients with two potentially related conditions such as "AIDS" and "Gastro-enteritis" it is not necessary for this combination to be represented in a single precoordinated or postcoordinated concept. Instead, it is possible to look for co-existence of the individual Concept "Gastro-enteritis" within the records of patients who also have "AIDS."

  • The advantage of this is that there is no need for the clinician to have made the association between the two conditions. Therefore a more complete assessment of the incidence of "Gastro-enteritis" in patients with "AIDS" can be made.
  • The disadvantage is that if a precoordinated or postcoordinated SNOMED CT representation of the combined concept is used, these records will not necessarily be computably equivalent to those with the two conditions recorded separately.

There is no absolute rule on when to use multiple statements associated using record structure constructs, and when to use intrinsic precoordinated or postcoordinated SNOMED CT representations. The decision maybe influences the functionality of a particular system and the specific user requirements that the system is serving. However, the following guideline is suggested:

Example:

71620000 |Fracture of femur| caused by "fall down stairs" should be represented as separated statements linked by an appropriate record structure component. The SNOMED CT Concept "Due to" could be used to name the link between these statements.


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