8. Existing Medical Record Number (MRN) based identification

I. Description of the Option

The current method of identifying a patient and patient information by the majority of organizations is based on the use of Medical Record Numbers. Each provider organization maintains a Master Patient Index (MPI) and the Medical Record Number is issued and maintained through this index. The MPI usually contains the patient's demographic information such as name, date of birth, address, mother's maiden name, SSN, etc. The Medical Record Number is used to identify an individual and his or her medical record/information. It is designed to be unique only within the same organization. The numbering system including the content and format of the medical record number is usually specific to the individual organization. Patients and providers will be required to use the respective Medical Record Number when dealing with different provider organizations. Recently, Hospital Information Systems vendors introduced the Enterprise-wide Master Patient Index which facilitates the mapping of a patient's Medical Record Number from one institution to another within the same enterprise. Since the Medical Record Numbers is unique only within the same organization, it does not adequately support access among multiple organizations or across the national healthcare system.

In order to facilitate queries and communication among these provider specific MPIs, software based solutions are being planned. Patient Identification Service by CORBAMed and HL7 MPI Mediation by HL7 are two initiatives that are currently underway. They are discussed in this report as alternatives to Unique Patient Identifiers. However, representatives involved in them indicate that in addition to the local identifier, a Unique Patient Identifier and a Central Trusted Authority are desirable to achieve their objectives fully.

II. Author/Proponent and Documentation

  1. Medical Record Number, also known as Unit Number and Patient Number is the current method of patient identification being used for purposes including delivery of care, record keeping and communication.
  2. Healthcare Organizations have the necessary policies and procedures in place for the use and management of Medical Record Numbers.

III. Compliance with ASTM Conceptual Characteristics

a) Functional Characteristics

Accessible: Identifiers are issued and maintained by the provider organization itself.

Assignable: Identifiers can be assigned by the provider organization itself.

Identifiable: The MPI maintained by provider organizations contain the necessary identification information.

Verifiable: Organizations with computerized issue of Medical Record Numbers have the check-digit verification capability.

Mergeable: Duplicate Medical Record Numbers are one of the problems facing the current institutional MPIs. Prevention of the issue of multiple Medical Record Numbers has been a challenge and the merger of the respective records a persistent problem in healthcare organizations. Merger is accomplished through cross- referencing.

Splittable: Instances of the same Medical Record Number assigned to multiple individuals are fewer in relation to duplicate issues. However, the ability to split the same medical record number assigned to multiple individuals faces the same problems as merging duplicate numbers and records. New numbers are issued to one or all individuals that have the same number.

b) Linkage of Lifelong Health Record

Linkable: Medical records within the same organization are linked together under the same Medical Record Number. However, the institution specific Medical Record Number does not provide adequate support to track or link medical records from multiple organizations or facilitate the electronic exchange of patient information.

Mappable: Does not apply; MRN is not a new identifier proposal.

c) Patient Confidentiality and Security

Content Free: Organization based MRNs are usually content free.

Controllable: Does not use encryption or decryption scheme to hide the identity of the individual

Healthcare Focused: MRN is healthcare focused.

Secure: Does not use encryption nor requires a trusted authority to enforce a secure identifier

Disidentifiable: Does not use encryption or decryption scheme to hide the identity of the individual

Public: MRN is not intended to be public information and will require access security protection.

d) Compatibility with Standards and Technology

Based on Industry Standards: Not based on standards. Medical Record Numbers have been in use for a long period of time. Many policies and procedures have been developed and implemented based on them.

Deployable: MRN is compatible with technologies such as bar code readers, scanners, etc.

Usable: There is no inherent barriers to the usability of the MRN by both manual and automated means..

e) Design Characteristics

Unique: Intended to be unique only within the same organization. Patients will have multiple Medical Record Numbers each issued by different organization providing care.

Repository-based: The Master Patient Index used in hospitals and provider organizations serve as the repository.

Atomic: The organization based MRN is atomic.

Concise: The organization based MRN is concise.

Unambiguous: Existing organization based MRN consists of numeric digits. Zeros and ones may present some ambiguity with letters "o" and "l" respectively.

Permanent: Patients will have multiple identifiers each issued by different organizations that delivered care. Within the same institution the identifier will be unique.

Centrally governed: The issue and maintenance of MRN s are managed by the provider organization itself.

Networked: MRNs are used within the same organization. There are no barriers to implementing it over a network.

Longevity: The scope of the MRN is limited to the same organization.

Retroactive: Does not apply. MRN is currently in use and not a new identifier proposal.

Universal: The scope of the organization-based MRN is not universal. It is intended only for patients visiting the organization.

Incremental Implementation: MRNs are already in use.

f) Reduction of Cost and Enhanced Health Status

Cost-effectiveness: This option leaves the existing method of identification in tact. Therefore, it will not require any new expenditure for implementation. On the other hand, it will preserve the status quo and not effect any change in the cost or the health status of the nation.

IV. Compliance with Unique Patient Identifier's Operational Characteristics

Currently operational: MRN is not currently operational as a Unique Patient Identifier.

Existing infrastructure: Does not have national level administrative or technical infrastructures. MRN is administered by respective provider organizations and it is unique only within the same organization.

Readiness of the required technology: The software initiative to facilitate query and communication among MPIs is the planning stage.

Timeliness: The effort to convert MRNs to be unique nationally or establish linkage or communication among independent institutional MPIs requires extensive planning, effort and enormous amount of time.

Adequacy of information to support identification functions: The organization- specific MPI does not contain information regarding records residing in other provider organizations.

V. Compliance with Unique Patient Identifier Components Requirements


MRN is organization-specific. It is not a Unique Patient Identifier. It is unique only within the organization that issued it.

Identification Information

The patient's demographic information collected and maintained by provider organizations are accessible for use only within the same organization.


The Master Patient Index currently used by provider organizations are specific to respective organizations. They are not mappable to the same individual's MRN in another organization.

Mechanism to protect, mask or encrypt the identifier

Encryption is not part of the current Medical Record Number.

Technology Infrastructure

The scope of the technology infrastructure is limited to operation within the same provider organization.

Administrative Infrastructure

The scope of the administrative infrastructure is limited to operation within the same provider organization.

VI. Compliance with Basic Functions Criteria

Access to geographically-distributed information requires the patient identifier to expand beyond an institutional level. The existing institution-based MRNs are adequate to manage the patient identification only within that institution. A robust identification method that can identify individuals uniquely across the nation and facilitate the linkage of their lifelong health record is the main objective of the Unique Patient Identifier. The institution-based MRN is not a Unique Patient Identifier. It does not comply with the Unique Patient Identifier's operational characteristics and component requirements. In the absence of these critical elements, the MRN lacks the ability to fulfill the basic functions discussed below.

Identification of individuals

Delivery of care functions: MRN is not a Unique Patient Identifier that can support identification across multiple organizations. The positive identification of an individual during delivery of care is possible only within the organization that issued the identifier.

Administrative functions: The identification for administrative functions required by practitioners, provider organizations, insurers, HMOs, federal health plan agencies, etc. is possible only within the organization that issued the identifier.

Identification of information

Coordination of multi-disciplinary care processes: The support for multi- disciplinary functions and coordination of care processes including ordering of procedures, medications and tests and communication of results is possible only within the organization that issued the identifier.

Organization of patient information and medical record keeping: The support for manual medical record keeping and automated collection, storage and retrieval of information during the course of delivery of care is possible only within the organization that issued the identifier.

Manual and automated linkage of lifelong health records: The MRN lacks the ability to identify, organize and link information and records across multiple episodes and sites of care.

Aggregation of health information for analysis and research: The Medical Record Number lacks the ability to support the aggregation of health information across multiple episodes from multiple providers for research, planning and preventive measures.

Protection of privacy, confidentiality & security

Access Security: Access Security procedures are applicable only within organization that issued the identifier.

Content-free Identifier: The Medical Record Number is content-free.

Mask/Hide/Encrypt/Protect/Disidentify: Does not use encryption.

Improve health status and help reduce cost

The Medical Record Number will retain status quo and not yield a Unique Patient Identifier solution to access across multiple providers, the creation of longitudinal record, etc.

VII. Strengths and Weaknesses


  1. Already operational
  2. Eliminates the effort, time and investment that will be required for developing and implementing a new identifier


  1. The existing Medical Record Number is not a Unique Patient Identifier.
  2. Meets only 14 of the 30 ASTM conceptual requirements fully
  3. Does not meet four of the five operational characteristics and none of the Unique Patient Identifier components' requirements
  4. Does not fulfill the basic functions of a Unique Patient Identifier adequately
  5. The existing medical record numbers are not able to support exchange of information across institutional boundaries. Although, use of an enterprise-wide MPI offers some help within an enterprise, the need for communication beyond an enterprise in turn led the industry in search for a Unique Patient Identifier.
  6. Sophisticated computer tools and software have to be developed and implemented to address the exchange of information from multiple institutions with multiple identifiers for the same patient. This task has been an unfulfilled challenge for the industry.
  7. Does not support tracking of a patient's other sites of care or record locations.

VIII. Potential Barriers & Challenges to Overcoming the Barriers

  1. Successful development of software applications to provide exchange of patient care information based on multiple Medical Record Number among multiple provider organizations nation-wide
  2. Ability to track patients' other sites of care and record locations
  3. Timely development of software applications to facilitate communication among MPIs
  4. User acceptance.

IX. Solutions to the Barriers:

Existing Medical Record Numbers are institution-specific and do not support identification across institutional boundaries. Therefore, successful development of software applications and communication technologies to track the various sites of care and to provide exchange of patient care information based on multiple Medical Record Numbers among multiple provider organizations nation-wide can facilitate the continued use of Medical Record Numbers.