When is software a medical device?
In each scenario below, would you consider the software to be a medical device?
- Software used to plan cancer treatment doses and to control the setting of oncology treatment devices
- Software used within the overall design and manufacturing processes of the medical devices
- Software used to measure and calculate the anatomical sites of the body to facilitate the irradiation of surgical intervention
- Software embedded in an implanted pulse generator device
- Software used to transmit administrative data such as a patient's name and address
The answers to the examples above are yes, no, yes, yes and no, respectively.
This exercise highlights the increasing prevalence and complexity of software in the medical industry, but also underscores the difficulty of determining if the software is a medical device and, if applicable, which classification rule to apply under the European Medical Device Directive MDD 93/42/EEC.
Many critical functions performed by medical devices are directed by software, and because software is not a visible product, sometimes, we lose sight of its importance. In 2000, medical device software occupied national headlines when 28 Panamanian teletherapy patients received radiation overexposure: the Multidata Systems International Corporation Treatment Planning Software was implicated in the deaths of 21 of those patients.
This is an extreme example but it emphasizes both how pivotal software is to the function of some medical devices and the consequences of software failure.
Software as a Medical Device Defined
So what is software? An example provided by MEDDEV 2.4.1, Rev. 8, Guidelines on the Classification of Medical Devices for a Rule 12 device describes active medical devices as "intended for recording, processing or viewing of diagnostic images." Guidance NB-MED 2.2, Rev. 4, Software and Medical Devices explicitly suggests the following categories of medical devices:
- Software intended for analysis of patient data generated by a medical device with a view to diagnosis and monitoring
- Software intended for use for by patients to diagnose or treat a physical or medical ailment (condition or disease)
- Software that is a component and integral part of a medical device
These sentences contain a few key words. Point A refers to "diagnosis and monitoring" of patient data, which is why the fifth scenario of software described in the quiz is not considered a medical device. The software in the fifth scenario tracks administrative patient data. Point C is subject to some interpretation, but essentially, if the device cannot operate without your software, your software is "integral" and assumes the same classification as the device as discussed below. The software categories all diagnose, monitor, treat or alleviate disease. Software in the second scenario facilitates the manufacture of devices, but is not indicated for alleviating disease.
Which Classification for Medical Device Software?
The MDD 93/42/EEC, Annex IX makes provisions for software that functions as a medical device. Basically, it states that any software that drives a device or influences the use of a device falls automatically in the same classification.
Clearly, software may be viewed as a medical device or an accessory to a medical device or as a component and integral part of a medical device (automatically in the same class as the medical device and subject to the conformity assessment of the medical device).
The function of the software guides the classification of the software medical device. If the software is a medical device, it may be classified as Class I; however, if the software medical device is an integral component of a device as indicated above, it assumes the classification of the device. For example, software that is part of a Class III medical device is viewed as a Class III device.
Software Is Viewed as an Active Medical Device
This may be another concept that is difficult to reconcile and reasonably well explained by the NB-MED guidance, which states: "Operation of software requires electrical energy and software functions by converting this energy by means of interfaces and/or actuators, which are parts of the programmable electrical medical system." The NB-MED guidance document is interesting, because it attempted to delineate some of the inadequacies of the European regulations with regards to software. Fortunately, the proposed revisions to the Medical Device Directive and the Directive for Active Implantable Medical Devices (AIMD) attempt to resolve these omissions.
Software as Medical Devices With a Measuring Function
One last nuance that should be discussed briefly is that potential Class I medical device software may be subject to classification as a Class I medical device with a measuring function. And, if the software now is viewed as such, Notified Body involvement is required for CE Marking.
The Guidance MEDDEV 2.1.5, Medical Devices with a Measuring Function may be relevant to some software. Software with a measuring function must meet a few characteristics: measure quantitatively a physiological function or anatomical parameter; measurement displayed in legal units or other acceptable units as described within European Directive 80/181/EEC; and the intended purpose implies accuracy, and failing to comply with the "measurement" could result in a significant adverse effect on the patient's health and safety.
To determine the proper European route to compliance for your software, consider the following questions:
- What is the intended use of the software?
- Does the intended use of the software designate it as a medical device? (The software provides instructions for an instrument for the purpose of diagnosis, prevention, monitoring, treatment or alleviation of disease.)
- If yes, is the software a component of a medical device? (The software drives or influences the use of the device.) If yes, the software assumes the class of the device.
- Is the software an independent device or accessory? If yes, does the software have a measuring function? If yes, perhaps the device is Class I measuring.
Revision of European MDD and AIMD
It is widely accepted that software is either a pivotal medical device or a component of a medical device. The revisions to the Medical Device Directive and AIMD reflect the issues regarding software and provide explicit references and clarification.
In the revised Medical Device Directive, the preamble specifically describes software and acknowledges the "growing importance of software in the field of medical devices." It is proposed that software be referenced in the definition of the medical device and a statement included that software may be used with the medical device. The following sentence will be added to Annex IX: "Stand alone software is considered to be an active medical device."
In the AIMD, the Essential Requirement on software will be elaborated to discuss software validation and development lifecycle, risk management, validation and verification.
Additional Considerations
Many ancillary topics also deserve mention. Conformity Assessment procedures require consideration of the development lifecycle; procedures for document control and configuration management; and control of combinations between software versions and intended hardware. Published software medical device standards (not an exhaustive list) include IEC 62304 (2006), Medical Device Software-Software Life Cycle Processes, ISO/IEC 90003 (2004) and IEC 60601 series.
Software is a component of many complicated medical devices or is an independent medical device or accessory, and as such, it is important for manufacturers to appreciate that their software may require CE Marking.
June 2007
