CHEMEDDosage ch-dosage-1 is wrong?

[dvribeira]

During some CH EMED EPR tests we noticed some systems where sending split dose statements with base dosage without a sequence field. Having a look at this I noticed that the ch-dosage-1 constraint seems to be wrong.

What I did to test this with a local build of CH EMED EPR was to add a constraint on the document entry level, on my case to the medication statement resource for testing it:

Invariant: ch-emed-epr-dosage-1-replacement
Description: "If more than one dosage is provided (split dosage), the base dosage must have sequence = 1."
Severity: #error
Expression: "dosage.count() > 1 implies dosage.where($this.conformsTo('http://fhir.ch/ig/ch-emed-epr/StructureDefinition/ch-emed-epr-dosage') and sequence = 1).exists()"

This solution seems to be working fine.

There might be better ways of solving this, though, since I am no FhirPath expert. If you think this is ok I can do it for CH EMED and open a PR (one invariant suffices but has to be added to CHEMEDMedicationStatement, CHEMEDMedicationRequest and CHEMEDMedicationDispense) myself.

Cheers!

[dvribeira]

Sorry just to clarify I'm aware the constraint I pasted does only the check for the split dose case and not the case of enforcing sequence is absent if simple dose. I just wanted to try the complex case, I would add the absent sequence check as well before doing the PR.

[dvribeira]

a full one:

Expression: "(dosage.count() > 1 implies dosage.where($this.conformsTo('http://fhir.ch/ig/ch-emed-epr/StructureDefinition/ch-emed-epr-dosage') and sequence = 1).exists()) and (dosage.count() = 1 implies dosage.single().sequence.exists().not())"

[ziegm]

21.03.2024 PJ, DV, QL, MZ, AB:
adapt the constraints

[ziegm]

@pjolo please review the changes.
@dvribeira please review the changes and may test it on your side.

• as information: we have to have the contraint ch-dosage-1, because it serves as a discriminator for the baseEntry and the additionalEntry
• added constraints
  • MedicationStatement: ch-dosage-medstat
  • MedicationDispense: ch-dosage-meddis
  • MedicationRequest: ch-dosage-medreq
• updated changelog

[dvribeira]

@dvribeira they are good , thanks!! :)

[pjolo]

The changes are good