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Unified Medical Language System® (UMLS®)

Metathesaurus - Mapping Projects


Basic Mapping Project Assumptions

Health care providers must produce billing and statistical data using the HIPAA code sets. The use of standard clinical vocabularies will be more attractive and cost-effective if required HIPAA code set data can be generated from health care information recorded using standard clinical vocabularies. For this reason, the National Committee on Vital and Health Statistics (NCVHS) and others have recommended that the Federal government support the production and maintenance of robust mappings from standard clinical terminologies to the HIPAA code sets. The NCVHS has also recommended mappings between standard clinical vocabularies and other important vocabularies, such as regulatory and interface terminologies. NLM has been recommended as the appropriate body to coordinate and/or develop and disseminate the mappings within the UMLS Metathesaurus.

NLM is proceeding to assist existing mapping projects and to set up new ones under the following basic assumptions:

  1. Mappings are sets of relationships of varying complexity established between two vocabularies in order to allow automated translation or connection between them. More specific concepts can generally be mapped accurately to more general concepts. Mappings cannot be used to add specificity to information that was captured at a more generic level.
  2. The producers of both vocabularies in any map must participate in the mapping effort to ensure that the result accurately reflects the meaning and usage of their vocabulary. At a minimum, both vocabulary producers must participate in defining the basic purpose and parameters of the mapping task, reviewing and verifying the map, developing the plan for testing and validation, and devising a cost effective strategy for building, maintaining, and enhancing the map over time.
  3. Target users of the map must participate in its design and testing to ensure that it is fit for its intended purpose.
  4. Production of mappings will be an iterative process, which must involve testing, validation, and use in real world settings. The functionality of mappings will improve over time as research, testing, and use determine (a) useful ways to construct and represent complex mappings (such as those that involve conditional rules) and (b) the extent they can be applied in the real world.
  5. The creation of mappings is likely to suggest ways to improve the vocabularies on both ends of the map.
  6. CMS and other payers must validate the process used to produce mappings that will be used to generate claims data from clinical data. As a result, CMS must be involved in developing plans for initial and ongoing testing and validation of these mappings.
  7. NLM may provide financial and, as necessary, technical support to vocabulary producers and others who participate in creating, reviewing, testing, and validating mappings.
  8. The new UMLS Metathesaurus Rich Release Format provides an appropriate distribution mechanism for purpose-specific mappings between pairs of vocabularies. NLM will distribute mappings between standard clinical vocabularies, HIPAA code sets, and other key vocabularies used in Federal health information systems within the UMLS Metathesaurus.
  9. UMLS users’ ability to use a mapping will be governed by their licenses to use the two vocabularies in the mapping.