What is eMPI? It is the Welsh master patient index — the national patient-identity reconciliation system that links a patient's records across NHS Wales systems. eMPI has been linked to patient record mixups (cases where one patient's data has been associated with another's record). The clinical-safety implications of patient-identity errors are direct: wrong information delivered to a clinician at the point of care.
What eMPI does
eMPI — the electronic Master Patient Index — is the national patient-identity reconciliation system for NHS Wales. It links a patient’s records across multiple systems (WPAS, RISP, EPMA, WCCG, primary care) using a canonical patient identifier. Patient identity is the foundational data quality dependency for every clinical IT system downstream of it.
Status
In operational use. No documented replacement programme on a clinical-safety-driven timeframe.
eMPI problems: patient record mix-ups
- eMPI has been linked to patient record mixups — cases where one patient’s data has been associated with another’s record. The clinical-safety implications are direct: a clinician acting on the wrong record can deliver the wrong intervention.
- Patient-identity errors in master-index systems are particularly dangerous because they are silent — the system does not flag uncertainty; the wrong data simply arrives at the clinical workflow.
- eMPI’s record-mixup incidents are documented in Digital Health and Care Wales (DHCW) board papers but the safety case has not produced structural correction.
Where this is discussed in the diagnosis
- Intervention 1: Competent Leadership — Action 6 names eMPI specifically for patient-safety triage (“patient record mixups”).
- Drift to Low Performance — the trap that allows a system with known patient-safety incidents to remain in operational use without remediation.