Expression (FHIRPath) for 'age' custom search parameter.

Hello,

I am not sure if this the right place to post my issue. If not, please redirect me to the right thread.

Environment: Docker deployment of IBM FHIR v4.10.0

Issue: I have several Patient resources and wish to perform search requests based on their age. From what I understand, age is not a standard search parameter, thus needs to be imported as a custom search parameter.

I see that on hl7 there is an age SearchParameter: https://www.hl7.org/fhir/patient-extensions-Patient-age.json.html The description of this search parameter says that: "description" : "Searches for patients based on age as calculated based on current date and date of birth. Deceased patients are excluded from the search." Thus I copy this json entry as-is, inside extension-search-parameters.json file and copy it inside my container when I fire up the server. However when I try to use it as a search parameter I always get 0 results, no matter what I try.

I also read that the IBM FHIR Server does not use the XPath during extraction; it only uses the expression (FHIRPath). But I am not sure what the correct FHIRPath is for IBM FHIR server, I can’t seem to find it anywhere.

Can you please help?

P.S. The only search parameter I managed to get to work was from this IBM example: https://ibm.github.io/FHIR/guides/FHIRSearchConfiguration#11-tenant-specific-parameters

My extension-search-parameters.json file is as follows:

{
        "resourceType": "Bundle",
        "id": "searchParams",
        "meta": {
                "lastUpdated": "2018-12-27T22:37:54.724+11:00"
        },
        "type": "collection",
        "entry": [
                        {
                          "fullUrl": "http://ibm.com/fhir/SearchParameter/Observation-component-code-value-boolean",
                          "resource": {
                                  "resourceType" : "SearchParameter",
                                  "id" : "patient-extensions-Patient-age",
                                  "url" : "http://hl7.org/fhir/SearchParameter/patient-extensions-Patient-age",
                                  "version" : "4.0.1",
                                  "name" : "age",
                                  "status" : "draft",
                                  "experimental" : true,
                                  "description" : "Searches for patients based on age as calculated based on current date and date of birth.  Deceased patients are excluded from the search.",
                                  "code" : "age",
                                  "base" : ["Patient"],
                                  "type" : "number",
                                  "xpath" : "f:Patient/f:birthDate",
                                  "xpathUsage" : "normal",
                                  "expression": ??????,
                                  "multipleOr": true,
                                  "multipleAnd": true
                          }
                        }
        ]
}

[lmsurpre]

Age is a tricky one because its a point-in-time thing. The search parameters are extracted and indexed at the time of ingestion. It possible to re-compute the values via our $reindex process but thats somewhat costly (based on the amount of data) and so you might not want to do it each day.

Can you search on birthdate instead?

[prb112]

Note, you have to update the Resource to get the new extraction of the SearchParameter values. An alternative is to use $reindex as Lee previously mentioned (which does not change the version-id).