FHIR’s Is-Modifier flag — don’t ignore it!

It looks like this: ?!

Most resources have at least one Is-Modifier element — usually ‘status’.

But what does it mean?

It means you can’t ignore it. If you’re processing this data in any way you need to look at the value and understand what it means.

Because it can be dangerous not to.

Take AllergyIntolerance as an example. Both the clinicalStatus and verificationStatus elements are Is-Modifier elements.

ClinicalStatus can have a value of ‘resolved’ and verificationStatus can have a value of ‘entered-in-error’. If either of these values are present, it can change the meaning of the resource.

Again: it can change the meaning of the resource.

  • entered-in-error means ‘not valid’
  • resolved means ‘a reaction to the identified substance has been clinically reassessed by testing or re-exposure and is considered no longer to be present’

Essentially, it means the Patient is not allergic after all.

If you populate a screen without checking for these statuses, your screen is in danger of passing false information on to the user.

Most status elements are Is-Modifier elements.

If you’re building a FHIR query, ensure the query asks for only the statuses you want to see. If you’re writing code that uses an Is-Modifier element, always check its value before using it.

The Is-Modifer property cannot be altered by profiles. It’s fixed.

More about Is-Modifier: http://hl7.org/fhir/R4/conformance-rules.html#isModifier



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