Retrieve MedicationRequest which doesnt have any MedicationDispense

[LKShankarKarthik]

Question

In our case, we have a scenario where we want to retrieve all FHIR MedicationRequest resources which does not have any associated FHIR MedicationDispense events (/resources).

Is there a way in FHIR Query to use modifiers on '_revinclude' or '_include' to achieve above requirement?

Appreciate any guidance on this please.

[mannawar]

First of all implementers would be the right person to answer this. But as a fallback mechanism you can use some thing like this as below. I just referenced firely as server.

` static async Task Main(string[] args)
{
CallWithoutReference();
}

private static async Task CallWithoutReference()
{
    var fhirServerUrl = "https://server.fire.ly/";
    var client = new FhirClient(fhirServerUrl);
    
    //1. Fetch MedicationRequests with their associated MedicationDispense resources
    var bundleWithDispenses = await client.SearchAsync<MedicationRequest>(new string[] {"_revinclude=MedicationDispense:medicationrequest" });
    var medicationRequestWithDispenses = bundleWithDispenses?.Entry.Where(e => e.Resource is MedicationRequest).Select(e => e.Resource as MedicationRequest).ToList();
    
    
    //2. Fetch all medication request
    var allMedicationRequest = new List<MedicationRequest>();
    Bundle bundle;

    var nextPageUrl = "MedicationRequest";

    do
    {
        bundle = await client.SearchAsync<MedicationRequest>(new string[]{$"_page=1&url={nextPageUrl}"});
        
        allMedicationRequest.AddRange(bundle.Entry.Where(e => e.Resource is MedicationRequest).Select(e => e.Resource as MedicationRequest));
        
        nextPageUrl = bundle.NextLink?.ToString();
    }while(nextPageUrl != null);
    
    //3. Filter now from those who have dispenses
    var dispenseIds = medicationRequestWithDispenses?.Select(req => req?.Id).ToHashSet();
    
    var medicationRequestWithoutDispenses = allMedicationRequest.Where(req => !dispenseIds.Contains(req.Id)).ToList();

    foreach (var req in medicationRequestWithoutDispenses)
    {
        Console.WriteLine($"MedicationRequest without Dispense: {req.Id}"); 
    }
}`

[EXPEkesheth]

Closing this issue as this is a question for FHIR implementers (refer to chat.fhir.org)