The Patient Master is the EMPI — enterprise master patient index. It answers the question every downstream service asks: who is this patient, are they already known, and are there duplicates?
Why a single index
Hospitals send overlapping MRNs and demographics. Without an EMPI, the same person becomes two patients and clinical safety breaks down.
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Stores patient demographics and identifiers.
Matches incoming records to existing patients.
Merges duplicate patient records.
The Patient Matcher scores incoming demographics against existing records.
New patients persist in the Patient Repository; probable matches link instead of duplicating.
The Patient Merger consolidates confirmed duplicates with full audit trail.
The EMPI exposes REST endpoints for lookup, create and merge operations used by ingestion and FHIR. The contract is on the Overview tab.
Contract
Merge operations require an idempotency key so retried ADT messages do not double-merge.