filter GCP FHIR QuestionnaireResponse resources by a linkId

Question

I'm Trying to filter the GCP healthcare Fhir QuestionnaireResponse by specific linkId. I have tried following queries in GCP FHIR Viewer.

• QuestionnaireResponse?subject=17feb145-2a59-12d6-12fd-193b04406402&_has:QuestionnaireResponse.item.linkId=3428208260818

• QuestionnaireResponse?subject=17feb145-2a59-12d6-12fd-193b04406402&QuestionnaireResponse.item.linkId=3428208260818

• QuestionnaireResponse?subject=17feb145-2a59-12d6-12fd-193b04406402&item.linkId=3428208260818

It's trying to filter the QuestionnaireResponse of specific patient and by the linkIds.

Answer 1

There is no standard search parameter defined to search by linkId. To perform that search, you'd have to define a custom SearchParameter and get the server in question to support it. Also, if searching by linkId, you should always also search by Questionnaire.url because the same linkId value can have completely different meanings in different Questionnaires.

In general, QuestionnaireResponse isn't designed to be searched based on the answers provided. The expectation is that data will be extracted into other resources (e.g. Observation) and will be searched that way. (Questionnaires are too non-standard and the meaning of answers is too dependent on other answers to safely search against answers in QuestionnaireResponse.)

Answer 2

In order to search on a field there has to be a search parameter defined for the field, either a standard param (which can be found at https://hl7.org/fhir/r4/questionnaireresponse.html#search for QuestionnaireResponse) or custom.

GCP supports custom search parameters - see the howto doc https://cloud.google.com/healthcare-api/docs/how-tos/fhir-custom-search

For this example you would want an expression of "QuestionnaireResponse.item.linkId". The custom param has a name of your choice, in the style of the standard you might choose link-id, and then once the search parameter was created and enabled using the configureSearch method, the search query would be QuestionnaireResponse?subject=xxx&link-id=yyy