Enterprise master patient index

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An enterprise master patient index or enterprise-wide master patient index is a database that is used across a healthcare organization to maintain consistent, accurate and current demographic and essential medical data on the patients seen and managed within its various departments. The patient is assigned a unique identifier that is used to refer to this patient across the enterprise. The objective is to ensure that each patient is represented only once across all the software systems used within the organization.[1][2] The essential patient data includes name, gender, date of birth, race and ethnicity, social security number, current address and contact information, insurance information, current diagnoses, most recent date of hospital admission and discharge (if applicable), etc.

EMPIs are intended to solve the common problem where multiple systems across the organization gradually become inconsistent with respect to the patient's most current data when the patient's information changes, and only one system is updated, i.e., the changes are not propagated to the others. A similar problem may be seen for non-healthcare organizations with respect to customer data.

Many software vendors use EMPI and MPI (master patient index) synonymously, because an MPI is only workable if it is used by all software applications across an entire enterprise: that is, "master" implies enterprise-wide scope.[3]


In computing, an enterprise[-wide] master patient index is a form of customer data integration (CDI) specific to the healthcare industry. Healthcare organizations or groups of them will implement EMPI to identify, match, merge, de-duplicate, and cleanse patient records to create a master index that may be used to obtain a complete and single view of a patient. The EMPI will create a unique identifier for each patient and maintain a mapping to the identifiers used in each records' respective system.

An EMPI will typically provide an Application Programming Interface (API) for searching and querying the index to find patients and the pointers to their identifiers and records in the respective systems. It may also store some subset of the attributes for the patient so that it may be queried as an authoritative source of the "single most accurate record" or "source of truth" for the patient. Registration or other practice management applications may interact with the index when admitting new patients to have the single best record from the start, or may have the records indexed at a later time.

An EMPI may additionally work with or include enterprise application integration (EAI) capabilities to update the originating source systems of the patient records with the cleansed and authoritative data.

A key component of an EMPI is the match engine.[4] A match engine may be deterministic, probabilistic, or naturalistic. [5] [6] The match engine must be configured and tuned for each implementation to minimize the false matches and unmatches. The accuracy and performance of the match engine are a big factor in determining the value and ROI for an EMPI solution.

The attributes a match engine is configured to use will typically include name, date of birth, sex, social security number, address and more. The match engine must be able to give consideration to typos, misspellings, transpositions, aliases, and more.[7]

Even the best tuned EMPI will not be 100% accurate. Thus an EMPI will provide a data stewardship interface for reviewing the match engine results, handling records for which the engine does not definitively determine a match or not. This interface will provide for performing search, merge, unmerge, edit and numerous other operations. This interface may also be used to monitor the performance of the match engine and perform periodic audits on the quality of the data.

Organizations that would use an EMPI include hospitals, medical centers, outpatient clinics, physician offices, rehabilitation facilities, etc.

Key benefits[edit]

By correctly matching patient records from disparate systems and different organizations, a complete view of a patient may be obtained. With this complete view, numerous benefits may be realized including:

  • Better patient care can be provided.
  • Improved customer service can be offered.
  • In emergency or other critical care situations, medical staff can be more confident that they know medical conditions or other information that would be critical to providing proper care.
  • Historical care related information can be obtained from across organizations.


Numerous companies provide EMPI products. Some are pure-play providers and others provide EMPI offerings as part of a broader MDM or integration solution. In addition there are healthcare industry specific MPI providers such as Stibo Systems Healthcare, Mohawk College, Care Data Systems, ARGO, QuadraMed, NextGate, Atlas,MultiVue, HealthUnity (ZeOmega), InterComponentWare Inc. (ICW), and InterSystems AppDevelopmentPartners LLC who offer commercially supported versions.

Open Source EMPI[edit]


External links[edit]