Moving from a legacy coding scheme to
SNOMED CT requires attention to be paid to continued accessibility and use of data encoded
using the legacy scheme.
The following general approaches may be applied or adapted taking accounts of the
capability of the
SNOMED CT enabled application and the value and relevance of existing data.
- Mapping or converting the data:
- Linking or integrating existing data:
- Archive or retain old data in its original form, and where it is necessary to retrieve
historical information, use
components from the legacy system to do this:
- This approach completely separates the new
SNOMED CT from the legacy data and is unlikely to be acceptable in clinical practice . However,
it may be appropriate for some data warehousing applications where the wholesale conversion
of data is considered too onerous.