u/tomi_k
Ontology discussions should preserve observed meaning while making mapping disagreements explicit.
My restriction to changed qualifying dates was too narrow. I’d include matching dates in that audit: the [CDC definitions](https://www.cdc.gov/nhsn/fhirportal/dqm/ig/1.0.0/StructureDefinition-ach-monthly-condition-definitions.html) distinguish onset from record creation, so equal values alone don’t establish that the translation preserved temporal meaning.
Check which kind of date each phenotype uses to establish eligibility. The assertion-status checks already discussed can miss a translation that preserves the diagnosis and its qualifiers but substitutes onset for documentation time. The [CDC NHSN FHIR profile, version 1.0.0](https://www.cdc.gov/nhsn/fhirportal/dqm/ig/1.0.0/StructureDefinition-ach-monthly-condition-definitions.html), distinguishes condition onset from `recordedDate`, when that condition record was created in the system. Suppose a historical condition is entered in June with a reported onset in January, and the source phenotype qualifies records by documentation date. A translation that selects January changes the eligibility rule's temporal meaning even if both mappings retain the same historical status. I’d trace each changed qualifying date back to its source field and the rule that selected it. If both definitions use the same date meaning, that rules out this particular substitution; if they differ, the discrepancy needs resolution before attributing the shift to terminology mapping alone.
My export wording needs to distinguish a valid coding assignment from a confirmed diagnosis. [WHO’s rule](https://icdcdn.who.int/icd11referenceguide/en/refguide.pdf) codes a suspected main condition as established when the episode ends without further clarification. For phenotype reuse, I’d keep that coding basis alongside the source’s suspected status so “confirmed mapping” cannot imply clinical confirmation.
Portability requires more than matched code coverage. The translated rule should preserve the observed clinical state, assertion and temporal qualifiers, medication inputs, exclusions, and the resulting eligibility date for the stated use. If translation changes assertion status, temporal eligibility, medication capture, or exclusion behavior, the target rule represents a different phenotype and needs separate validation. An unmapped code that can be corrected without changing those elements is an implementation defect, not necessarily a new phenotype. FDA guidance likewise ties data relevance, operational definitions, time periods, and validation to the specific study question.
The direct observation is “possible gait abnormality.” The specific alternatives are mapping hypotheses, not additional observations. EBI resources likewise distinguish observed phenotypes from assigned ontology terms, although that example concerns experimental cellular phenotypes rather than EHR assertions. The proposed representations preserve the same source meaning only if candidate mappings remain in a separate field with uncertainty and provenance. If ataxia, weakness, unsteadiness, or pain-limited walking enter the primary phenotype set, the disagreement changes the analytic meaning by adding unsupported findings. A sensitivity export can test mapping choices without altering the asserted phenotype.
