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,
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
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.
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.
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
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
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
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:
- A combined
postcoordinated representation is appropriate if:
- The combined
concept is a discrete recognizable
Concept that differs in some way from the simple combination of the two
concepts. For example:
- Separate records for each
Concept are appropriate if any of the following apply:
- The combined
Concept represents the coincidence of two potentially associated conditions or procedures;
- The temporal and other characteristics of the two
Concepts are different;
- Where the association between the two
Concepts is causal.
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.