UDI Form and Content: FDA Offers Draft Guidance

Posted 25 July 2016 By Zachary Brennan


The US Food and Drug Administration (FDA) on Monday released new draft guidance to help define the expected content and forms of the Unique Device Identifier (UDI), to assist both medical device labelers and FDA-accredited issuing agencies in ensuring that UDIs are in compliance with the UDI Rule.


A UDI is composed of (1) a device identifier (DI), (2) typically one or more production identifiers (PIs) when included on the device label, and (3) the data delimiters for the DI and PIs included in the UDI.
Under 21 CFR 801.20, a UDI is required on the label and package of every device in commercial distribution in the US, unless an exception or alternative applies.

The UDI Rule, establishing the UDI system, was published on 24 September 2013 and aims to adequately identify devices through distribution and use to improve their safety. The UDI must be issued by an FDA-accredited issuing agency that operates a system that conforms to international standards. Under the rule, FDA established a phased, risk-based, approach to UDIs, which are tracking tags used to improve the safety of medical devices. The rule began applying to Class III devices in 2014, and implantable, life-supporting and life-sustaining devices in 2015. Class II devices will need to comply later this year and Class I and non-classified devices will need to have UDIs in 2018.

According to FDA, the UDI must be presented in two forms on the label and device packages: easily readable plain-text and automatic identification and data capture (AIDC) technology. When a device must bear a UDI as a direct marking, the UDI may be provided through either or both easily readable plain-text and AIDC technology forms. In addition to the UDI label requirements, labelers must submit product information concerning devices to FDA's Global Unique Device Identification Database (GUDID), unless subject to an exception or alternative.

Draft Guidance

Under Monday’s 10-page draft guidance document, which stakeholders can comment on for the next 60 days, FDA makes clear that the AIDC form of UDIs should be scanned or otherwise used for the identification of the device whenever possible to minimize errors in records resulting from manual transcriptions.

UDIs, particularly when provided through AIDC technology, will allow rapid and accurate data acquisition, recording and retrieval, particularly for patients, health care professionals, FDA and other users of the UDI system to read and enter the UDI into patient records, reports to FDA and other data systems without any technological assistance.

Additionally, the easily readable plain-text form may be used as a failsafe to capture the UDI if the AIDC form cannot be scanned or used. Easily readable plain-text, according to FDA, “means the legible interpretation of the data characters encoded in the AIDC form of the full UDI, including the data delimiters. The easily readable plain-text form of the UDI should include the device identifier (DI), production identifiers (PIs), and data delimiters contained in the UDI, and be limited to those characters specified under ISO/IEC 646.”

The easily readable plain-text form of the UDI may be presented as a single line or multiple lines of text and should be displayed below or near the AIDC technology form of the UDI, the guidance says.

As far as the AIDC, FDA defines it as any technology that conveys the UDI or the DI portion of a UDI of a device in a form that can be entered into an electronic patient record or other computer system via an automated process.

“The labeler should also test that the AIDC form of the UDI is generated in such a way that the UDI can be reliably read at the point of scanning by the applicable type of technology,” FDA says. “Due to space limitations or other reasons, the AIDC form of the UDI may be split into multiple segments. For example, one UDI may be presented in two linear bar codes: one bar code for the DI and another bar code for the PIs. These two bar codes should be proximally located to each other on the device label, device packages, and when required, on the device itself.

In addition, FDA says the DI bar code should precede the PI bar code, though the labeler may choose to use more than one type of AIDC technology form to assist users who may be employing different methods of UDI capture technology.

“For example, a labeler may include a linear bar code and data matrix code (2-D) on the device label, both representing the same UDI. In this instance, only one easily readable plain-text form of the UDI should be on the label and should be in near proximity to one of the AIDC forms of the UDI. If a labeler chooses a bar code form of AIDC, the bar code form of the UDI should be tested for print quality,” FDA says.

In addition, FDA says it is up to the discretion of the labeler to determine how best to disclose the presence of AIDC technology that is not evident upon visual examination. FDA also says it does not require a specific type of marking or a symbol, providing the labelers greater flexibility and reduced burdens.

Content of UDI

FDA says it interprets the statute as specifying that a UDI is composed solely of a single DI and one or more of the five PIs listed in 21 CFR 801.3 and 801.40(b), along with the data delimiters for the DI and PIs.

“While some of the FDA-accredited issuing agencies may allow for non-UDI elements, such as quantity, in the UDI carrier, we do not recognize any such additional non-UDI elements as being part of the UDI,” FDA says. “The UDI Rule does not include any additional requirement to place any of the five elements that would be considered a PI on the label. There are some situations where a UDI may comprise a DI only.”

For instance, the UDI of a Class I device is not required to include a PI, though for other devices, if one or more of the five PIs are included on a device label, the UDI must include each of the PIs that appears on the label.

FDA also makes clear that data delimiters are key to UDI comprehensibility and utility, and delimiters for the DI and PIs should be included in the UDI.

“The data delimiters indicate the DI value or the PI values that follow each data delimiter within the UDI, and may also indicate other non-UDI elements that may be included within the UDI carrier,” FDA says.

The data delimiters allow users to parse the DI and PIs from the easily-readable plain text UDI, as well as to verify that the information encoded in the AIDC form of the UDI matches the easily-readable plain text form of the UDI.

As far as the UDI carrier, the draft says that the UDI should precede any non-UDI elements.

“The easily readable plain-text form of the UDI should be ordered to specify the DI first, followed by the PIs. If there are any non-UDI elements in the UDI carrier, the non-UDI elements should follow the PIs that are part of the UDI. For example, if the label of a particular device bears the expiration date PI and quantity, and the labeler wishes to include the quantity in the UDI carrier, the easily readable plain-text of the UDI carrier should display the data delimiter for the DI, followed by the DI; the data delimiter for expiration date, followed by the expiration date PI; and lastly, the data delimiter for quantity, followed by the quantity,” FDA says, noting that for this example, the agency does not prohibit the inclusion of quantity in the UDI carrier, though quantity is not considered part of the UDI and the data delimiter for quantity should be separate from the DI and PI data delimiters in the UDI.

Unique Device Identification System: Form and Content of the Unique Device Identifier (UDI) Draft Guidance for Industry and Food and Drug Administration Staff

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