Who assigns a unique ID to the patient? A guide to healthcare identification

October 3, 2025 •

4 min read

According to the American Health Information Management Association, up to 10% of health records are duplicates or fraudulent, a fact that highlights the difficulty in accurate identification. This makes it more complex to determine who assigns a unique ID to the patient and how records are managed across different providers.

Quick Summary

Healthcare identification relies on a decentralized system where individual hospitals and clinics assign their own unique medical record number (MRN), supplemented by master patient indexes (MPIs), matching algorithms, and emerging technologies like biometrics to ensure proper patient identification within and across different systems.

Key Points

Decentralized System: In the U.S., individual healthcare organizations, not a national body, assign medical record numbers to patients.
Medical Record Number (MRN): Each hospital or clinic typically assigns its own unique MRN, which only works within that specific system.
Enterprise Master Patient Index (EMPI): Larger healthcare networks use an EMPI to consolidate multiple identifiers from various facilities into one patient record.
Patient-Matching Algorithms: Software uses demographic data and other information to link patient records across disparate systems in the absence of a universal identifier.
Patient Misidentification Risks: Errors like duplicate records or data overlays can lead to significant patient safety issues and inaccurate medical information.
Emerging Technology: Biometrics and radio-frequency identification (RFID) offer highly accurate identification solutions but come with their own set of challenges and privacy concerns.

The Decentralized Model of Patient Identification in the U.S.

In the United States, there is no single, universally adopted standard for a unique patient identifier. This system is largely decentralized, with individual healthcare providers and facilities assigning their own identification numbers. A hospital, for instance, assigns a unique medical record number (MRN) to every patient whose record it maintains. This MRN is used to track all patient interactions and medical information within that specific hospital or healthcare system. This decentralized model, while functional for a single institution, makes tracking a patient across different providers and health systems a significant challenge.

The Role of the Enterprise Master Patient Index (EMPI)

To overcome the limitations of siloed patient records within a single healthcare system, many organizations utilize an Enterprise Master Patient Index (EMPI). An EMPI is a system that identifies and links all the various identifiers associated with a single patient across different departments and facilities within that larger system. For example, if a hospital network includes an emergency room, a pharmacy, and several clinics, the EMPI ensures that a patient's records from each of these disparate systems are correctly associated with a single, unified patient identity. Most EMPIs use patient-matching algorithms to perform this crucial function.

The Impact of Private Companies and Health Information Exchanges

Beyond individual hospital systems, private companies and regional health information exchanges (HIEs) also play a significant role in patient identification. Companies like Experian Health use advanced referential matching technologies that cross-reference vast datasets to create universal patient identifiers (UPIs) that can link records across disparate healthcare systems. These identifiers are not patient-facing but are used by providers and payers to create a more comprehensive view of a patient's record across the healthcare ecosystem. Similarly, HIEs facilitate information sharing by using an EMPI to cross-reference multiple patient identifiers from various participating health organizations.

The Crucial Process of Patient Matching

In the absence of a national unique patient identifier, the accurate matching of patient records is paramount for safety and continuity of care. This process is typically performed by sophisticated algorithms that compare multiple demographic data points.

Deterministic Algorithms: These are the most straightforward, classifying records as a match only if they meet a specific, predefined threshold of agreement, often based on a unique identifier combined with other non-unique ones, such as date of birth.
Probabilistic Algorithms: These are more advanced and can characterize the uncertainty in a matching process. They assign a statistical likelihood that two records belong to the same person, allowing for variations like typos or name changes.

The Risks and Implications of Misidentification

When patient records are not accurately matched, significant risks arise. Incorrectly combining two different patients' records is known as an 'overlay,' while incorrectly splitting a single patient's record creates duplicates. This can lead to serious medical errors, including incorrect diagnoses, wrong-person procedures, and missed test results. According to Health Affairs, the average rate of duplicate records in a healthcare system was as high as 18% in 2018. Efficient patient identity management leads to high patient identity integrity, which is vital for patient safety.

Patient Identification Methods at a Glance


Method	Assigning Entity	Scope	Accuracy	Privacy Concerns
Medical Record Number (MRN)	Individual hospital or clinic	Limited to one healthcare system	High within a single system	Low, for internal use
EMPI-assigned ID	Enterprise healthcare system	Across multiple facilities in a network	High, with algorithmic matching	Moderate, links data across multiple departments
Biometric ID (e.g., finger scan)	Healthcare facility with biometric tech	Dependent on provider's technology	Extremely High	High, involves sensitive personal data
Referential Matching ID	Private vendor	Across multiple disparate systems	High, based on external data sources	Moderate to high, uses broad data sets

Future Directions and Emerging Strategies

The healthcare industry continues to explore emerging strategies for improving patient identification. Biometrics, which use unique physical characteristics like fingerprints or facial patterns, offer a highly accurate solution but require investment in specialized technology and raise some privacy concerns. Furthermore, radio-frequency identification (RFID) tags are being explored for enhanced tracking. The ongoing push for a national unique patient identifier in the U.S. remains contentious due to privacy issues but is widely supported by the health industry for its potential to improve safety and efficiency. A full overview of patient identity management strategies can be found in a National Center for Biotechnology Information (NCBI) publication here: Managing Patient Identity Across Data Sources - NCBI.

Conclusion

In summary, the question of who assigns a unique ID to the patient has a multi-layered answer, primarily resting with individual healthcare systems and supplemented by advanced technological solutions. While a centralized national system has been halted by privacy concerns in the U.S., the use of EMPIs, sophisticated matching algorithms, and biometrics helps ensure patient records are correctly linked. Understanding this complex landscape is key for both healthcare professionals and patients seeking to improve the accuracy and integrity of health information.

Frequently Asked Questions

No, there is no single, universally adopted national unique patient identifier in the United States. Due to privacy and security concerns that arose from HIPAA, individual healthcare systems each assign their own identifiers, which can make tracking a patient across different facilities challenging.

An EMPI is a system used by large healthcare organizations to create a single, unified record for a patient by linking all their various identifiers from different internal departments, such as billing, the lab, and the electronic health record (EHR) system.

To differentiate patients with similar names, healthcare providers must use at least two identifiers, such as the patient's full name combined with their date of birth. Modern systems also use probabilistic algorithms to match records based on a statistical likelihood of a match.

The risks of patient misidentification include medical errors, compromised patient safety, and incomplete health records. It can lead to 'duplicate records' (a single patient with multiple records) or 'overlays' (different patients' data combined into one record).

While the Health Insurance Portability and Accountability Act (HIPAA) initially called for a national unique identifier, Congress imposed a funding ban in 1998 due to widespread concerns about patient privacy and data security. That ban has remained in place.

Biometrics, such as palm vein or facial recognition, offer a highly accurate method for identifying patients because they are unique to each individual and difficult to replicate. This technology helps prevent human errors and enhances security.

The 'two-identifier' rule is a patient safety practice where healthcare staff must use at least two pieces of identifying information—such as a patient's name and date of birth—before administering care or performing a procedure to confirm their identity.

Yes, some private companies, like Experian Health, have developed universal patient identifiers (UPIs) by leveraging large datasets. These are not national standards but can help link records across different providers and payers who use their services.