Still Comfortably Numb: FDA Issues Revisions to Previous MDDS Guidance

Footnotes for this article are available at the end of this page.

Recently, the Food and Drug Administration published a revision to its final guidance document titled, “Medical Device Data Systems, Medical Image Storage Devices, and Medical Image Communications Devices,” originally issued on February 9, 2015. The agency updated certain areas of the guidance to be consistent with the final rule, “Medical Devices; Medical Device Classification Regulations To Conform to Medical Software Provisions in the 21st Century Cures Act.”1 FDA amended these medical device classification regulations so that the regulations conform to the medical software provisions in the Cures Act. The updated guidance also includes some minor changes to address industry comments. AGG prepared a Bulletin on the initial guidance.2

Background and Overview

  • According to its 2015 document, FDA defined a Medical Device Data System (MDDS) as:

A device that is intended to provide one or more of the following uses, without controlling or altering the functions or parameters of any connected medical devices:

        1. The electronic transfer of medical device data;
        2. The electronic storage of medical device data;
        3. The electronic conversion of medical device data from one format to another format in accordance with a preset specification; or
        4. The electronic display of medical device data.

A MDDS could include “software, electronic or electrical hardware such as a physical communications medium (including wireless hardware), modems, interfaces, and a communications protocol; this identification did not include devices intended to be used in connection with active patient monitoring.”

  • However, in December 2016, certain software functions were removed from the definition of a “device” under section 201(h) of the Food, Drug, and Cosmetic Act, based on the 21st Century Cures Act.3 As such, the guidance now differentiates between “Non-Device-MDDS” and “Device-MDDS” to highlight software versus hardware functions, and how the sole intention of these functions determine how (or whether) the product is regulated.
    • Non-Device-MDDS are “software functions that are solely intended to transfer, store, convert formats, or display medical device data and results.”
    • Device-MDDS are “hardware functions that are solely intended to transfer, store, convert formats, or display medical device data and results.”

(Emphasis in the guidance)

  • In short, if the product is a Non-Device-MDDS, it is not a device. If the product is a Device-MDDS, it is a device, but the agency does not intend to enforce compliance with basic regulatory requirements. If the product does not meet either of these definitions, it is not a MDDS.

FDA Policy for Non-Device-MDDS

  • To maintain consistency with the 21st Century Cures Act, the guidance clarifies that such Non-Device-MDDS no longer fall under the definition of “device” and, thus, are not subject to FDA oversight. The agency provides examples of Non-Device-MDDS software functions that meet the Non-Device MDDS definition. Those that fall outside of the Non-Device MDDS definition are considered Device-MDDS, which are medical devices.
    • Examples of software functions “solely intended to transfer, store, convert formats, or display medical device data and results” (therefore, Non-Device MDDS and not devices) include:
      • the electronic transfer or exchange of medical device data, e.g., software that collects output from a ventilator about a patient’s carbon dioxide level and transmits the information to a central patient data repository, or an application that transmits a child’s temperature to a parent or guardian while the child is in the nurse’s office at school;
      • the electronic storage and retrieval of medical device data, e.g., software that stores historical blood pressure information for later review by a healthcare provider;
      • the electronic conversion of medical device data from one format to another in accordance with a preset specification, e.g., software that converts digital data generated by a pulse oximeter into a digital format that can be printed; and
      • the electronic display of medical device data, which may include certain secondary or remote displays to medical devices that solely display data and results, e.g., software that displays a previously stored electrocardiogram for a particular patient, or applications that remotely display information such as the most recent blood glucose value or time lapse between blood glucose measurements (but without the intention to be used for taking immediate clinical action).
    • The new guidance clarifies that such Non-Device MDDS functions are no longer “device functions,” where FDA considered such examples as MDDS software functions under the 2015 guidance. Further, the updated guidance clarifies that a Non-Device-MDDS does not analyze or interpret data.
    • Software functions that modify, analyze, or interpret data, or control the functions or parameters of any connected medical device, are considered medical device functions.
    • Software functions intended to generate alarms or alerts, such as those typically used for active patient monitoring, are medical device software functions; such functions require a timely response in a clinical context or in response to clinical decisions.
    • The agency clarifies that, if a product has multiple functions, including at least one device function and at least one software function that is not a device, FDA will not regulate the Non-Device-MDDS functions contained in a multiple function device product.

FDA Policy for Device-MDDS

  • Device-MDDS, or those hardware functions that are intended to transfer, store, convert formats, or display medical device data and results, remain under the definition of “device.”
  • As was described in the previous FDA guidance, the agency does not intend to enforce compliance with basic regulatory requirements that apply to these devices.
    • Devices that do not modify the data and do not control the functions or parameters of any connected medical devices may include the following types of product regulations:
      • hardware intended for the electronic transfer, storage, or conversion of medical device data as outlined under 21 C.F.R. § 880.6310;
      • medical image storage devices subject to 21 C.F.R. § 892.2010; and
      • medical image communications devices subject to 21 C.F.R. § 892.2020.
    • In contrast, the following do not fall under FDA’s enforcement discretion (thus requiring adherence with applicable device laws):
      • specialized medical display hardware devices for digital mammography, radiology, pathology, and ophthalmology; and
      • other specialized medical display hardware integral to the safe and effective use of a medical device hardware product, e.g., integral 3-D displays in robotic surgery systems and displays built into ICU bedside monitors.
    • However, where certain software functions are utilized on hardware, such as to transfer, store, convert formats, or display medical device data and results, but the hardware manufacturer did not intend this utilization, FDA would not consider such product a “device” and would not regulate it.
    • In the new guidance, FDA clarifies that certain specialized items of medical equipment are medical devices that would not be considered a Device-MDDS. These specialized items would be regulated as medical devices, and would be held to ordinary regulatory oversight.
    • Further, the agency provides that, at this time, it will not enforce the FDC Act regarding products with multiple functions, if at least one of those functions is a Device-MDDS function.

AGG Observations

  • As software and hardware functions become more prevalent among medical devices, FDA is seeking to provide further clarification to industry as to when a particular product will be regulated, and, if so, which regulations should apply.
  • For those products that fall under FDA’s enforcement discretion, it is important to realize that the product remains regulated by FDA. The discretion only exempts the product from regulatory control requirements (such as including registration and listing, pre-market review, post-market reporting, and quality system regulation for manufacturers).
  • FDA adds specificity and examples to this guidance; manufacturers should review the guidance to evaluate whether product fall into the regulatory framework. The manufacturer does not want FDA asking, “Is there anybody out there?”


[1] 86 Fed. Reg. 20278, (April 19, 2021), available here:

[2] AGG’s previous Bulletin on the initial guidance is available here:; the Federal Register notice for the 2015 guidance is available here: 80 Fed. Reg. 6996 (Feb. 9, 2015).

[3] See 21 C.F.R. § 880.6310.