Strategies for Updating Terminology Mappings and Subsets using SNOMED CT

SNOMED CT® (SCT) is a large, comprehensive medical terminology with many applications in the health care IT sector. SCT is often mapped to existing billing classifications as well as to proprietary terminologies in order to support access to and from SCT from existing applications. Subsets of SCT are used to reduce complexity and size. These subsets can vary from small sets that will be used to populate drop down lists in electronic medical record applications and larger lists that are used for reference, e.g. the SCT Non-human subset. There are costs and time limitations in maintaining mappings and subsets, particularly after each SCT release when concepts are retired and new concepts are added. There is a need for a careful strategy to identify changes, determine which changes need to be reviewed, and to rank changes so they can be reviewed systematically in order of importance. Here we outline our updating strategies for the Health Language Medical Specialty Subsets, a list of 10,000 SCT terms grouped into 45 subsets. These strategies can be used for any subset of SCT as well as for mappings created to and from SCT.