Part Three: Unique Patient Identifier

Unique Patient Identifier

Access to geographically-distributed information requires the patient identifier to expand beyond an institutional level. Existing institution-based medical record numbers are adequate to manage patient identification only within that institution. A robust identification method that can identify individuals uniquely across the nation is essential. The entire healthcare industry including patients, providers and regulatory bodies will benefit from the development and application of a Unique Patient Identifier. Information and communication technologies needed to develop and use such an identifier are currently available.

Industry Initiatives

The need for Unique Patient Identifiers has become urgent and critical. The widespread implementation of information technology and the emergence of computer-based patient records have paved the way for its potential success. Several organizations started to address this issue of Unique Patient Identifier since the beginning of this decade. In 1993, the Computer-based Patient Record Institute created a work group to address the need for a Unique Patient Identifier. Several organizations such as WEDI, AMIA and ACMI called for action in this area by publishing position papers. In 1995, American Society for Testing and Materials (ASTM) published a Standards Guide for the Properties of a Unique Patient Identifier called Universal Health Identifier (UHID). Other organizations such as American National Standards Institute - Healthcare Informatics Standards Planning Panel (ANSI-HISPP), HCFA, HIBCC and NABP worked on identifiers relating to providers, employers, health plans, payer, etc. In 1994, ANSI-HISPP created a task group to review the various options in this area. The recent legislation, Health Insurance Portability and Accountability Act (HIPAA) 1996, requires the implementation of health data standards including identifier standards.

The need for a Unique Patient Identifier and its potential benefits have been recognized widely. Twelve (12) state governments have initiated steps to address this need and an unknown number of private initiatives have emerged to develop a suitable Unique Patient Identifier methodology. The American Health Information Management Association recommends the use of a Unique Patient Identifier to be included in the core data elements of the MPI. The Core Health Data Elements, published by the National Committee on Vital Health Statistics (NCVHS), also includes the use of a Unique Patient Identifier. Industry-wide initiatives such as MPI workshops, consortia initiatives such as OMG/CORBAMed Patient Identification Service and standards organizations initiatives such as HL7 MPI Medication, etc. highlight both the significance of the need for a Unique Patient Identifier and the industry's endeavors to fulfill it. A total of twelve (13) options have been recommended by various proponents. This report includes an analysis of these options.

The Significance of Unique Patient Identifier

Patient Identifier must be unique to meet the critical patient care objectives, such as access to care and patient information, communication, linkage of lifelong health record, population-based studies and integration of information systems. A patient identifier that is non-unique within the national healthcare system presents significant risks and challenges in the following areas:

a) accessing and integrating information from different providers and their information systems.

b) aggregating and providing a lifelong view of a patient's health information

c) supporting population-based research and development

d) cost effectiveness

e) timely access to critical patient care information

f) protecting the privacy and confidentiality of patient information

g) timely delivery of care

h) fraud and abuse, etc.

Currently, the JCAHO Information Management Standards require the following:

1) continuity of care among multiple providers and times (IM#.6)
2) inclusion of patient identification information as part of the patient medical record (IM.3 & IM.7.2 )
3) positive identification of the patient for patient care functions such as blood transfusion (QC.5.1.5)
4) use of Unique Patient Identifiers (QC.5.1.4).

A patient identifier that is unique across the entire national healthcare system will facilitate an easy implementation, reduce cost and complexity, and assure timely access to information for patient care, administrative and research purposes.

Unique Patient Identifier - Definition

The identity of an individual consists of a set of personal characters by which that individual can be recognized. Identification is the proof of one's identity. Identifier verifies the sameness of one's identity. Patient Identifier is the value assigned to an individual to facilitate positive identification of that individual for healthcare purposes. Unique Patient Identifier is the value permanently assigned to an individual for identification purposes and is unique across the entire national healthcare system. Unique Patient Identifier is not shared with any other individual.

Unique Patient Identifier - Basic Functions and Objectives

A Unique Patient Identifier has the potential to assure prompt access to healthcare information, timely delivery of care, linkage of lifelong health records of individuals, aggregation of health information for analysis and research.

The four (4) basic functions that a Unique Patient Identifier must support are:

1) Identification of an Individual:

a) for the purposes of delivery of care (diagnosis, treatment, blood transfusion, medication, etc.)

b) for administrative functions (e.g. eligibility, reimbursement, billing, payment, etc.)

2) Identification of Information:

a) Identification and access to patient information for prompt delivery of care during current encounter, coordination of multi-disciplinary patient care services and communication of orders, results, supplies, etc.

b) Organization of patient care information into a manual medical record chart or an automated electronic medical record for both current and future use

c) Manual and automated linkage of various clinical records pertaining to a patient from different practitioners, sites of care and times to form a lifelong view of the patient's record and facilitate the continuity of care in future

d) Aggregation of information across institutional boundaries for population-based research and planning

3) Accurate identification functions (to provide timely access to patient care information) and dis-identification functions (to support the protection of security, privacy and confidentiality of patient information)

4) Reduce healthcare operational cost and enhance the health status of the nation by supporting both automated and manual patient record management, access to care and information sharing.

Identification of Individuals

Positive Identification for the Delivery of Care

Individual practitioners and provider organizations depend on Unique Patient Identifiers for positive identification of the patient. It is necessary to provide care during the current visit and refer to information from previous visits. Sensitive procedures such as blood transfusion, invasive testing, surgical procedures, medication administration, etc. require positive identification of the patient to prevent mistakes and is mandated by regulatory requirements.

Positive Identification for Administrative Functions

Individual practitioners, provider organizations and other secondary users of healthcare information such as private insurers, health maintenance organizations, federal health plan agencies and employers depend on Unique Patient Identifiers for positive identification (ID) of the patient for verification of eligibility, billing and reimbursement, etc.

Identification of Information

Access to Patient Information and Coordination of Multi-disciplinary Functions

Healthcare is a multi-disciplinary process. Unique Patient Identifier is used to communicate with the members of the multi-disciplinary services. For example, the identifier is used for activities such as ordering of procedures, medications, laboratory tests and radiology examinations, as well as for obtaining and communicating results of tests, procedures and examinations.

Organization of Information & Record Keeping

Both the manual record keeping and automated collection, storage and retrieval of information use Unique Patient Identifier. Medical record keeping functions such as medical record chart assembly, chart analysis, chart completion, medical record abstracting, etc. require the use of a Unique Patient Identifier. Data entry, electronic file organization and retrieval also require a Unique Patient Identifier.

Manual and Automatic Linkage of Lifelong Health Records

The primary focus of healthcare is shifting from treatment of diseases to disease prevention and promotion of health and wellness through consumer education. The health information will cover the entire life span of an individual. The health record of an individual may begin with genetic and prenatal data and end with that individual's death. Therefore, the Unique Patient Identifier can be used to:
a) organize information and documents within a single visit or episode of care,
b) organize information and documents within the same provider organization and
c) identify, organize and link information for the entire life of the individual across multiple providers, institutions and episodes of care.

Both manual charts/files and electronic health information require such an identifier for their creation, maintenance and use.

Aggregate Health Information for Analysis and Research

Practitioners, payers, researchers, policy makers, managers of health systems and care takers of public health need to aggregate health information on the basis of groups of patients, regions, diseases, treatments, outcomes, etc. The Unique Patient Identifier must facilitate such aggregation and linkage of health information for multiple patients across different geographic regions and times.

Support the Privacy, Confidentiality and Security Protection Functions Relating to Patient Care Information

A reliable identifier helps ensure authorized access and assures protection against unauthorized access. The right to anonymous care and the protection of security, privacy and confidentiality of patient information are major concerns in using a Unique Patient Identifier in a computerized environment. Together with the access control mechanism, the Unique Patient Identifier must aid in protecting the confidentiality of patient information and in identifying the perpetrators who violate patient confidentiality.

Cost Reduction and Improved Care through Access to Information

Through improved access to information, the Unique Patient Identifier: a) enables the prompt delivery of care during the current encounter, b) facilitates continuity of care, c) supports quality of care, d) reduces cost of integration and e) promotes optimum use of information technology.

Components & Processes Integral to Unique Patient Identifier

The Unique Patient Identifier must include components that will provide the various functional capabilities discussed in this report earlier. The identification process includes searching MPIs, matching identifiers, verifying identification information, etc. Depending on the identifier's scope and level of use, these search processes may range from a single provider organization to the entire national healthcare system. Therefore, the Unique Patient Identifier should be supported by a robust technical and administrative infrastructure. In essence, the Unique Patient Identifier will require multiple components to work together to perform its functions and fulfill its objectives. The following six (6) components are integral parts of the Unique Patient Identifier:

  1. An Identifier (numeric, alphanumeric, etc.) Scheme
  2. Identification Information
  3. Index
  4. Mechanism to hide or encrypt the Identifier
  5. Technology infrastructure to search, identify, match, encrypt, etc.
  6. Administrative infrastructure including the Central Governing Authority


Patient Identifier is frequently a numeric value such as a sequential or a group of random numbers. Options such as Cryptography Based Identifier and Biometric Identifier however, include numeric and non-numeric characters.

A set of Patient Identification (demographic) Information

The Identifier identifies a patient by matching his or her identification information. Reliable matching of the individual with his or her patient care information requires appropriate amount and category of identifying information relating to the individual and his or her patient care information. Such information falls into the following categories:

a. Permanent Data Segment

This segment contains the name and permanent (unchanging) personal data such as date of birth, place of birth, mother's maiden name, etc.

b. Longitudinal Data Segment

This segment contains corroborating information that occur over the lifetime of a person such as address, social security number, state driver license number, profession, name of the spouse, etc.

c. Health Service Data Segment:

This information helps to locate and identify the individual's previous health records and includes type of service, provider ID, date of service, etc. The MPI currently used by hospitals includes such information at an organizational level.

For the Unique Patient Identifier to be effective at all levels, all three segments described above must be available.


The index links the Unique Patient Identifier and the identification information of the patient. It serves as the directory of Unique Patient Identifiers. It must be capable of supporting identification functions within an organization, an enterprise and across the entire national healthcare system.

Organizational Master Patient Index (Organizational MPI)

Individual providers and organizations that treat patients maintain, an index of their patients, called Master Patient Index (MPI). It contains the patient identifiers and the patient's identifying personal and demographic information. The MPI maintained by organizations are unique only within the organization. It serves as a directory of patients for ready reference, verification and identification of the patient and patient information.

Enterprise-wide MPI (EMPI)

Managed Care and Integrated Delivery Network are the results of healthcare reform and related initiatives. Such initiatives bring organizations together and require interoperability among them. An enterprise may contain multiple cooperating provider organizations. The enterprise-wide MPI (or EMPI) provides cross reference to the multiple provider specific MPIs so that a patient's information can be accessed across the enterprise based on the patient's identifier.

Registry MPI (RMPI)/Software Mediation

Registry MPI is a new concept. It is also called the directory of MPIs. RMPI maintains pointers to those MPIs that are external to the enterprise MPI. RMPIs form a framework for facilitating the searching and matching of patients among different providers and multiple enterprises across the nation. Computer software to support the RMPI mediation functions is being planned by organizations such as HL7 and CORBAMed.

Information from Previous episodes of care and different Sites of Care

Organizational MPIs usually contain information relating to a patient's previous visits. Also, information on previous episodes of care from another organization, but within the same enterprise, can be obtained with the use of the EMPI. However, to access records or information from previous episodes of care from an unrelated organization, the respective site information is essential. Sites external to the enterprise will not be available from the EMPI. Although a RMPI can facilitate searching for a match among cooperating MPIs, sites unknown to a RMPI cannot be accessed for the search.

Protection of Patient Identity (Encryption)

Protection of the identity of a patient can be accomplished with the use of technology such as encryption. Encryption provides protection to patient identifiers when such protection is needed. For example, when communicating sensitive information such as HIV tests or other similar information, the identity of the patient must be protected. Different encryption schemes will yield different encrypted identifiers for the same patient. Only authorized users will be able to decrypt such encrypted identifiers.

Technology Infrastructure

In order to issue, maintain and manage the Unique Patient Identifier, a robust technology infrastructure that includes computer systems, communication network and powerful software applications is required. Such technology will help issue nationwide identifiers, handle encryption and decryption schemes and maintain the data base of identifiers and information relating identifiers.

UPI Communication/Network & Computer Hardware

Unique Patient Identifier has a nation-wide scope. In the future, it can expand to a worldwide use. Therefore, appropriate communication protocols and methodology must be utilized and the operation must be supported by sophisticated and powerful computer and communication networks.

UPI Software Solutions

The Unique Patient Identifier technology infrastructure should include software applications and communication capabilities that are necessary to perform identification functions, matching patient information and verification of identifiers. Such a computer network must provide nationwide-access twenty four (24) hours a day, 7 days a week and 365 days a year.

Administrative Infrastructure

An administrative infrastructure is required to manage and control the various functions relating to the issue, use and maintenance of the identifier. These functions include:

  1. Issue of the identifier
  2. Encryption and decryption of the identifier
  3. Linkage between the encrypted identifier and non-encrypted identifier
  4. Centralized or distributed data base of patient demographic information
  5. Assurance of the uniqueness and integrity of the identifier
  6. Resolution of conflicts and problems associated with identifiers

Central Trusted Authority

Lack of a Unique Patient Identifier and of a mechanism to track the previous sites of care for an individual leaves a significant gap in the process of identification of a patient and his or her information from previous treatments. A Central Trusted Authority with appropriate power can help fill this gap. In addition, the integrity of the patient identifier is essential to access the patient information reliably; the identifier and the demographic identification information are both highly confidential. The Central Trusted Authority can address these critical functions effectively. The ASTM Standard Guide for Properties of Universal Health Identifier (UHID) and other current Unique Patient Identifier proposals call for the establishment of a Central Trusted Authority. The Central Trusted Authority can be a government agency, a semi-government entity, or a private organization.

In summary, the need for an EMPI, an RMPI, or the Central Trusted Authority, depends on the level of use of an identifier. For example, if the scope of use of an identifier is limited to within a single provider organization it will not require either an EMPI, an RMPI, or a Central Trusted Authority. Access to patient information among multiple enterprises across the nation will require these components.

Processes Integral to Patient Identification:

The identification process varies depending on the scope of access and the level of use of an identifier. The scope may be limited to a single organization, an enterprise, or multiple enterprises across the nation.

Within a Single Organization

Here, the level of use of the patient identifier is at the lowest level (level I). Manual, as well as automated processes, are already in place. The procedures have been well established and a very good control mechanism is in place. Each provider or provider organization maintains an index of patients who were treated. The index may be manual or automated. A simple card file may serve as a master index in small organizations, and an automated index may be the choice for a larger organization. The index file usually contains the patient's demographic and identification information such as name, date of birth, address, mother's maiden name, SSN, etc. Smaller organizations may use just the name as the identifier. Large organizations that treat a large number of patients with multiple patients with the same name might choose to use a patient identifier such as a medical record number, unit number, or SSN. The patient identifier is used to quickly look up the index to recognize an individual; the demographic information associated with the patient identifier is used to verify and confirm the identity of the individual and his or her record. A majority of provider organizations uses the medical record number/unit number as the patient identifier. These identifiers are designed to be unique only within the same institution. The numbering system used by healthcare organizations is specific to the individual organization. V.A. hospitals, Medicare and the Department of Defense use Social Security Number (SSN) to identify patients.

Enterprise Wide Access (Multiple Provider Organizations)

In response to the Integrated Delivery Network and Healthcare Reform driven initiatives, HIS vendors have developed software solutions that address EMPI functions. EMPI is also known as Corporate MPI. This software solution provides the mapping of an identifier from one provider organization to another within the same enterprise. Several implementations are underway.

Nation Wide Access (Multiple Provider Organizations)

There are two different approaches to addressing the nation-wide access. The first one involves an MPI look up with the use of a Unique Patient Identifier for a match. The second involves the search of an MPI with a given set of demographic information. This method will utilize a weighting algorithm to help the search. The probability of success increases with the use of increased number of demographic characteristics. Organizations such as HL7 and CORBAMed are pursuing the second approach. In fact, both these approaches are complementary to each other. They can become more effective when used together.


In summary, a simple look up is all that is needed to identify and locate a patient or patient information under a patient identification system designed for use within a single provider organization. An enterprise with multiple provider organizations will require the use of an EMPI, which maps patient identifiers from one organization to another within the enterprise. Patient identification across the entire national healthcare system however, will require additional components and processes such as 1) UPI, 2) RMPI, 3) Central Trusted Authority and 4) powerful and sophisticated computer software for searching, matching and identifying patients.