Specification - Extended

HL7 CDA® R2 IG: C-CDA Templates for Clinical Notes DSTU Release 2.1 - US Realm

Document Description

extended per extended per TSC tracker 12437, again with 14128 and jira.hl7.org/browse/TSC-38

Existing Wording

In the errata release from 2018, the wording for Table 313 (UnitsOfMeasureCaseSensitive) says: "The UCUM code system provides a set of structural units from which working codes are built. There is an unlimited number of possible valid UCUM codes." There was not valueSet linkage at that time. In the errata release from 2019, the Table number changed to Table 316 and wording was revised to: "(Clinical Focus: Common UCUM units. This value set is based on the Common UCUM set.),(Data Element Scope: unit of measure),(Inclusion Criteria: all valid UCUM units case sensitive),(Exclusion Criteria: ) This value set was imported on 6/29/2019 with a version of 20180509. Value Set Source:https://vsac.nlm.nih.gov/valueset/2.16.840.1.113883.1.11.12839/expansion" By inserting a link to a valueSet (hosted in VSAC) of only 810 possible UCUM code permutations, this introduced a significant limitation to systems working to achieve C-CDA schematron conformance. Specifically, the following conformance criteria specify this UCUM valueSet with a SHALL binding: (CONF:1198-8842) Immunization Activity doseQuantity@unit (CONF 1098-7526) Medication Activity doseQuantity@unit (CONF 1098-7525) Medication Activity rateQuantity@unit (CONF 1098-32130) Planned Immunization Activity doseQuantity@unit (CONF:1098-32133) Planned Medication Activity doseQuantity@unit (CONF:1098-32134) Planned Medication Activity rateQuantity@unit (CONF:1198-31484) Result Observation value@unit (CONF:1198-8555) Social History Observation value@unit (CONF:1098-31579) Vital Sign Observation value@unit Here is the link to the current valueSet in VSAC with 810 concepts: https://vsac.nlm.nih.gov/valueset/2.16.840.1.113883.1.11.12839/expansion This valueSet misses many valid UCUM concepts. For example "cm/s" is not included while there are LOINC codes where this is the example unit (https://loinc.org/79922-1/). It appears that this list was created based on results data and may not include valid codes more appropriate for immunizations, medications and social history. For example {packs}/d is a valid UCUM expression for tobacco use but not included.

Proposed Wording

Since UCUM is a grammar with limitless codes, the change in wording and valueSet reference is incorrect in context of a SHALL binding. If there is a desire to maintain a valueSet in VSAC, the unit binding to this valueSet needs to be SHOULD rather than SHALL. There could remain a SHALL binding to UCUM as an infinite code set not enumerated in VSAC. If there is no desire to maintain a valueSet in VSAC, the reference to a specific valueSet in VSAC should be reverted to the language from the 2018 release.