The Useful Life of Medical Devices

In the regulatory landscape of medical devices, safety and performance are always at the forefront. In particular, manufacturers are required to establish the useful life of their device and ensure that safety and performance are guaranteed throughout the defined useful life.

But what exactly does useful life mean for a medical device, and why is it so crucial to define and manage it? This concept does not have a specific definition in Regulation (EU) 2017/745 (MDR); however, there are some references to it in various parts of the MDR, including:

• GSPR 6 (Annex I): The characteristics and performance of a device shall not be adversely affected to such a degree that the health or safety of the patient or the user and, where applicable, of other persons are compromised during the lifetime of the device indicated by the manufacturer, when the device is subjected to the stresses which can occur during normal conditions of use and has been properly maintained in accordance with the manufacturer’s instructions.
• GSPR 23.4 (Annex I): The instructions for use shall contain information on how to carry out calibrations and maintenance to ensure that the device functions properly and safely throughout its intended lifetime.
• Article 18: Among the information to be provided to a patient with an implant is also the expected lifetime of the implanted device.
• Articles 83 and 86: As part of post-market surveillance, relevant data on the device must be collected and analyzed throughout the expected lifetime of the device.
• Annex XIV, Part B: Post-market clinical follow-up (PMCF) is also an activity that must be carried out throughout the expected lifetime of the device.

It is therefore clear that adequately defining the useful life of a device is an obligation for the manufacturer and that it is necessary to take these legislative requirements into account when defining it.

What is the Useful Life of a Medical Device?

It is possible to find a definition of useful life and some guidance in various technical standards and guidelines (European and international):

• MDCG 2022-21 (PSUR): The lifetime of the device is the period specified by the manufacturer during which the device is expected to remain safe and effective for use.
• MDCG 2020-8 (PMCF): The expected useful life should be defined during the design input phase, also considering the state of the art for a specific intended use.
• IMDRF Essential Principles of Safety and Performance: The expected useful life is the period during which the device maintains safe and effective use, considering stability, maintenance, repairs, or upgrades.
• EN ISO 20417 (Information to be supplied by the manufacturer): The expected useful life is defined as the period during which the device remains safe and effective for use.
• EN 60601-1 (Medical electrical equipment – Part 1: General requirements for basic safety and essential performance): It is the period of time specified by the manufacturer during which the ME equipment or ME system is expected to remain safe for use (i.e., maintain basic safety and essential performance). It is also the period during which all risk control measures must remain effective to ensure that risks remain acceptable. In the accompanying documents, the manufacturer shall provide information that allows the responsible organization to assess when the ME equipment is approaching the end of its useful life. Such information shall include the expected service life as determined by the manufacturer (e.g., in terms of years of service or number of uses), but could also include tests to be performed as part of preventive maintenance or other criteria to allow the responsible organization to make an appropriate decision. The need for such information and the appropriate way to present it should be addressed as part of the risk management process.
• EN ISO 17664-1 (Processing of health care products — Information to be provided by the medical device manufacturer for the processing of medical devices — Part 1: Critical and semi-critical medical devices): Number of reprocessing cycles and/or lifetime to which a medical device can be subjected and remain suitable and safe for its intended use.

In summary, the useful life is the period established by the manufacturer during which the device maintains its safety and performance.

This implies that the risk control measures adopted must remain valid and effective, ensuring that the risks associated with the device remain acceptable. Furthermore, the manufacturer is required to provide the user with indications on the useful life (e.g., methods and tests to determine when the useful life has been reached) and on the activities to be performed (e.g., routine maintenance or repair activities) during this period of time. The useful life should be considered as design input, providing for adequate verification activities and tests to support it.

Useful Life: Practical Examples

The useful life and related considerations vary significantly depending on the type of device and its characteristics of performance and safety. It is therefore useful to look at some specific types of devices and the considerations that can be made to determine their useful life.

Active Devices

• The useful life is typically expressed in years or number of uses.
• The materials and components of the device are analyzed to identify those that could be subject to non-repairable failures and therefore determine the disposal of the device. The lifespan of these components must be estimated: the one with the shortest duration also determines the useful life of the device. For some components, technical data sheets may already provide useful information in this regard (e.g., mean time before failure, MTBF). It’s important to remember that the device must remain safe even in a single fault condition (cf. EN 60601-1).
• It is necessary to provide the user with a list of periodic maintenance activities and any functional and safety tests to be performed during the declared useful life. The time interval between maintenance or repair activities should not be confused with the useful life of the device, which ends with its disposal.

Software

• Software has no physical components that deteriorate, so it can be complex to define the useful life.
• One can therefore consider the estimated time between 2 major SW releases, which may be due to obsolescence of some SW components (including SOUPs, Software of Unknown Provenance), obsolescence of the HW on which the SW runs, compatibility with the operating system (considering the end of life declared by the manufacturer) or in reference to the state of the art of the technologies used (e.g., updates to more secure communication protocols).
• The user must be informed about how SW updates are managed and the estimated useful life.

Implantable Devices

• Safety must be considered for the entire implanted life of the device. Although a device may have a performance specification of ten years (i.e., it maintains its performance for the indicated period), safety must be considered for the entire duration of the implant, which may exceed the declared useful life. In fact, the removal of an implantable device at the end of its useful life is not always possible from a clinical safety perspective for the patient (considering the need for surgical intervention).
• The analyses and considerations that can be made include: the implantation time necessary to achieve the intended use (e.g., fracture consolidation), mechanical fatigue resistance (e.g., the number of stress cycles the device withstands), resistance to wear and corrosion, the duration of the energy source for active implantable devices (e.g., pacemaker battery), data derived from PMCF or equivalent devices in the state of the art and other clinical studies.
• The patient must have complete information on the useful life, including any necessary follow-ups during the implantation period.

Sterile and Single-Use Devices

• For single-use devices, the useful life ends with the use of the device itself.
• If the device is sold sterile, it is necessary to indicate the shelf life, i.e., the period of time within which the sterility of the packaged device is guaranteed when stored under the specified environmental conditions. The shelf life is determined through specific tests: in order to obtain useful data to initially determine (in first certification) the shelf life, it is possible to perform accelerated aging tests; however, real-time aging testing is still required to have more reliable and realistic data (see ISO 11607-1, ch. 8.3).
• The shelf life is declared through an expiration date that is reported on the sterile packaging of the device.

Reusable Devices after Reprocessing

• Reusable devices after reprocessing require the execution of several phases at the end of their use and before a new use, such as decontamination, cleaning, disinfection or sterilization. The typical example is reusable surgical instruments.
• The useful life of such devices is expressed in number of reuses; in fact, the use of the device and the reprocessing it undergoes involve wear and a progressive loss of functionality (e.g., the cutting ability for a scalpel).
• The manufacturer must therefore establish the maximum number of uses and possibly also tests or checks to be performed on the device to control its functionality and safety. Usually, a test is documented in which the device is subjected to the maximum number of reprocessing cycles established, verifying the effects in terms of wear and functionality each time up to the maximum number of cycles declared.
• The user must be informed of the maximum number of reprocessing cycles that can be performed on the device and any required tests and checks to be carried out periodically to monitor the performance and safety of the device.

Substance-based and Absorbable Devices

• These devices usually include biological materials or substances that can degrade over time or be absorbed by the human body.
• For substance-based devices, a shelf life is usually established for the packaged device and a maximum period of use once it is opened (e.g., a liquid solution for contact lenses must be consumed within a certain period of time after opening); to determine this period of time, stability tests are usually performed for the specific substance, verifying the maximum time for which it remains “functional” (i.e., does not degrade and lose its performance and safety).
• For invasive or implantable devices that are absorbable, the time required for reabsorption and the functional useful life are considered, i.e., the time necessary to achieve its intended use, as well as the mechanical strength and integrity until reabsorption (e.g., for absorbable sutures, the time during which adequate mechanical strength is guaranteed and the time needed to support tissue healing are considered).

Tests Supporting the Declared Useful Life

Declarations regarding the useful life must be supported by objective data and evidence. These can be pre-clinical and clinical data. Manufacturers must ensure that such data is collected throughout the declared lifetime of the device.

• Pre-clinical data: these are all data derived from type tests, analyses, and considerations before the device is actually used for its intended purpose; usually, these are the data used in the initial certification phase and before placing on the market and include: statistical analyses on the components and materials of the device (e.g., MTBF), data derived from mechanical, wear or corrosion tests, shelf life and stability tests, tests on reprocessing cycles, assessments on the obsolescence of components and technologies used, etc.
• Clinical data: these are data derived from clinical studies and clinical investigations conducted on the device or equivalent devices; they also include data that must be collected and evaluated through PMCF activities, to monitor the safety and performance of the device throughout its useful life. These data are of fundamental importance especially for implantable devices, in relation to the long-term effects due to implantation. Data derived from post-market activities (PMS) are also fundamental to confirm the initially estimated useful life (this implies that it may also be necessary to correct the estimate of the useful life based on such data).

Conclusions

Finally, we can summarize all the concepts seen above in the following points:

• Define the useful life: manufacturers must define the time period for the expected useful life in the technical documentation and make it available to the user through the instructions for use. The useful life is the period of time during which the device maintains its safety and performance; the useful life must be defined quantitatively (e.g., number of years, number of uses).
• Integrate into design: the useful life of the device must be considered as a design input, with test criteria and acceptance as design outputs and functional verification tests. This includes verifying each element of the device’s useful life with supporting tests.
• Use clinical data: clinical data, including PMS, PMCF, and PSUR, can be used as supporting evidence throughout the device’s lifetime. Performance and safety profile must be demonstrated for the entire expected useful life, ensuring that the positive risk-benefit profile is maintained.
• Monitor over time: manufacturers must collect and analyze relevant data through post-market activities to verify that the estimated useful life is consistent with the actual one.

The correct and adequate definition and management of the useful life of a medical device are therefore fundamental activities to ensure compliance with the legislative requirements of the MDR and, above all, to ensure the safety and effectiveness of the product for patients and users. In particular, it is essential to inform users clearly and unambiguously about the expected useful life and the maintenance and verification activities required during it.