The criteria for a successful implementation of SNOMED CT includes the customization of SNOMED CT to meet user needs. The order in which SNOMED CT components are displayed is often important for data entry and searching. This topic is further explored in the Search and Data Entry Guide. In general, rational ordering of selectable items depends on the nature of the application and its operating environment. The table below shows examples of ordering data entry items and search results rationally.
Examples of rational ordering
| Approach | Description | Example | Reference Set |
|---|---|---|---|
| Sequential ordering | Showing descriptions associated with high priority concepts before those associated with a lower priority. | Ordered reference set | |
Prioritization | Showing concepts with a high priority before their siblings using hierarchical display results. |
| Association reference set |
Initially listing concepts and associated descriptions with a priority above a specified threshold and requiring additional steps to access those assigned a lower priority. |
|
Sequential Ordering
An example of displaying items for data entry rationally is organizing list items in an order which is logical for the end users. If subsets of SNOMED CT concepts or descriptions are displayed during the process of data entry an 5.3. Ordered Reference Set can be used to specify the order in which the components should be displayed, as illustrated in the figure below.
Example of how an ordered reference set can be used to order items in a drop down list
Examples of presenting concepts presenting concepts (or descriptions) in an order that is rational or helpful for a particular purpose irrespective of the term displayed, include:
- Body parts including fingers, cranial nerves and vertebrae
- Enumerated values and scales including frequencies, severities and stages
The table below shows how the order of cranial nerves can be specified in an ordered reference set. The order attribute is used to indicate the sequential order of each subset member. Note that the linkedToId is set to 0 in this case because this refset does not specify nesting of the refset members
An ordered reference set used to specify the order of cranial nerves
| refsetId | referencedComponentId | order | linkedToId |
609999999102 | Cranial nerve simple reference set | | 1 | 0 | |
609999999102 | Cranial nerve simple reference set | | 2 | 0 | |
609999999102 | Cranial nerve simple reference set | | 3 | 0 | |
609999999102 | Cranial nerve simple reference set | | 4 | 0 | |
609999999102 | Cranial nerve simple reference set | | 5 | 0 | |
609999999102 | Cranial nerve simple reference set | | 6 | 0 | |
609999999102 | Cranial nerve simple reference set | | 7 | 0 | |
609999999102 | Cranial nerve simple reference set | | 8 | 0 | |
609999999102 | Cranial nerve simple reference set | | 9 | 0 | |
609999999102 | Cranial nerve simple reference set | | 10 | 0 | |
609999999102 | Cranial nerve simple reference set | | 11 | 0 | |
609999999102 | Cranial nerve simple reference set | | 12 | 0 |
If there is a need to specify an alternative hierarchical structure to support navigation, this can be achieved by specifying an alternative hierarchical view using an ordered reference set.
Prioritization
Some situations may require a set of refset members to be grouped, for example the set of most commonly used concepts in a particular specialty, department or data entry scenario. In this case, you may want to use the ordered reference set for prioritization instead of a purely sequential ordering of each member. Prioritization is similar to ordering, but also supports assigning the same rank to multiple components. A common use of prioritization is to support rational ordering of concepts or descriptions for display of data entry items and search results. More advanced uses may also be required, for example where the priority order is used to trigger certain decision support features or data entry options.
Illustration of how rational display of data entry options can be supported by specifying a priority order of the refset members.
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