FHIR search for duplicate patients

We use FHIR, but we've had a few customer accidentally create a new Patient instead of finding and adding data to an existing patient creating duplicate entries for the same real-life patient.

I'd like to search for patients with same DOB and similar names and then offer them UI in the app to merge their records.

My questions are:

1. What's the most efficient way to do this search in FHIR without having to retrieve and compare every Patient resource?
2. What's the cleanest way to transfer related patient resources to one of the patients as part of a merge?

Thanks in advance.

Your solution here is ultimately going to depend upon the FHIR server and/or EHR that you are connecting to.

In terms of being able to search for patients with similar demographics, in an ideal world, you would make a patient search API call with the demographics and the FHIR server would return not only patients with matching demographics but also patients with a similar set of demographics. (E.g., returning John Smith with DOB 4/3/1921 in addition to Johnathan Smith with DOB 4/3/1921). Epic does this and uses a point-based system to essentially assign a weight to a potential patient match.

In terms of merging, doing this over FHIR would require the server to support something like a $merge operation. I personally am not aware of any major EHRs that support this. Usually merges are handled via HL7 ADT interface messages (there are a few message types, like A18 and A34, that would fit the bill and again, it'll depend on the server's capabilities).