Data used to categorize individuals for identification, records matching, and other purposes.

Data Element

Patient Social Security Number
Records patient’s social security number.


Unified Comment from CDC

  • NOTE - This comment supports the promotion of the Data Class Patient Demographics - Data Element Identifier to USCDI V3 as well as the additional Data Element of Identifier System, including the allowance of multiple instances of Identifier/ Identifier System per patient. We believe that this will allow needed flexibility to accommodate use and exchange of the variety of patient identifiers in current use in the US. An example of this approach is: Identifier: 333224444, Identifier System: If ONC does not choose to incorporate this approach (Identifier + Identifier System) in USCDI V3, we recommend allowing for the following Patient Demographic Data Class Data Elements in USCDI V3: Medicare Patient Identifier, Medical Record Number and Social Security Number.  
  • Data element description: The Social Security Number is a 9-digit number issued to almost all U.S. citizens and eligible U.S. residents. It is used to track Social Security benefits and for other identification purposes.  
  • General Comment: The Social Security Number is used as a patient identifier by many Health Care Organizations and their EHRs and other HIT systems. It is also a required field in death certificates in the US. Social Security Number has a system element of the FHIR Identifier data type of: . The reviewers of this comment should be aware of the following HL7 US Core Patient Profile “Profile specific implementation guidance” notation: “The Patient’s Social Security Numbers SHOULD NOT be used as a patient identifier in Patient.identifier.value. There is increasing concern over the use of Social Security Numbers in healthcare due to the risk of identity theft and related issues. Many payers and providers have actively purged them from their systems and filter them out of incoming data.” ( ) Although this comment agrees that some health care organizations are beginning to decrease or eliminate their use of Social Security Number use for patient identification, we believe that this HL7 guidance is not nearly representative of the current status of patient identifiers in the US. Social Security Number continues to be one of, and in some case the primary, identifier of patients for health systems in the United States. Given appropriate safeguarding of this as well as any other form of protected health information, continued use of Social Security Number likely to occur for the foreseeable future in the healthcare ecosystem. Indeed, given Social Security Number’s use in social service agencies, its use as an important identifier for Social Determinants of Health purposes is likely to grow. Social Security Number is used in the MedMorph Health Care Surveys, Cancer Registry Reporting and Birth Defects Public Health use cases to link records within each registry. For Health Care Surveys and Cancer Registry Reporting, it is further used to link to the National Death Index and several CMS datasets. For these reasons this commentor strongly supports promotion of Social Security Number to inclusion in USCDI V3. Should ONC not find enough support to promote Social Security Number to inclusion in USCDI V3, promotion to USCDI Level 2 is another option, allowing acknowledgement that this is a widely used and exchanged data element yet allowing more and diverse input in the debate of its ultimate advisability for inclusion in a USCDI version.

Specific Identifier(s) or general Identifier?

MedMorph supports the addition of Patient Social Security Number (Level 1), but is concerned with having a general Identifier element (level 2) as well as Medical Record Number (Level 1) and Medicare Patient Identifier (Level 2). What is the intention of Identifier - is it a placeholder for a national identifier of some sort for a patient? We recommend that USCDI either take a general approach with Identifier Type, Identifier System, and Identifier Value OR be specific with Medical Record Number, Medicare Patient Identifier and Social Security Number elements (and remove the Identifier element).

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