Some terms are also encountered in the MDR, not very different from the MDD era. Among these, perhaps the most important issue could be considered as "Determining the lifetime of a medical device."
Annex I to the MDR (GSPR 6) states; "Safety and performance requirements should ensure that the device, as specified by the manufacturer, does not compromise the health or safety of the patient or user during normal use." We agree on that what is intended here is the determination of the lifetime of a medical device and the creation of the necessary verification evidence for this period. But when asked how to implement the MDR, we see a hazy path, which is one of the most important discussion topics in our training sessions.
There is actually a very valid reason for this.
"As a law, no single pathway that can address such a diverse range of medical device products."
Recently, the "Medical Device Lifetime" guidance was published by Team NB. I believe that this guide will be very helpful for the manufacturers when starting shelf life studies or reassessing shelf life for the MDR audits.
Firstly, the guidance emphasizes the unique characteristics of different types of devices in terms of how long they will stay safe and work properly. For example, each device has different safety needs compared to a device with moving parts or a software only device, or even to implantable devices that deal with both mechanical stress and our body's reactions.
Also, the fact that a device goes for service or maintenance does not mean its lifetime is over. Sometimes devices are repaired and still function strongly. But the key point is this: they should remain safe and function correctly until disposal, in compliance with the rules as stated in the EN ISO 14971 standard.
The main recommendations of the Team NB guidance are as follows:
- Manufacturers should define the lifetime of their devices, considering all details from production to the end of use, covering the entire lifetime. This should be in compliance with the regulations and guidelines.
- Devices cannot have an infinite lifetime. Specific time periods, such as years or usage, are crucial. Standards guide this. Tests conducted by the manufacturer at this stage should reflect real-world usage.
- Data obtained from various sources, such as post-market studies, should support the device's lifetime. The safety and performance should remain robust throughout its lifetime.
- When clinical data is lacking, other sources, such as existing studies or device features, come into play. For example, device usage stages such as reaction time, absorption, HALT/HASS testing, safety information, functional usage, and the risk/benefit ratio can be considered.
- Manufacturers justify the uniqueness of their devices or tests based on risks and standards.
These recommendations of the guidance cover all medical device manufacturers. However, there is a significant variation in how manufacturers of different devices work and what they consider when defining the lifetime of their devices. Manufacturers are advised to align their technical specifications with the risks and potential failures of their devices. The way to do this is through proper and detailed risk management.
When we talk about the lifetime of a device, it is not just the time from the first use to disposal. It also relates to how long it is beneficial for the person using it from the moment it is first manufactured until it is discarded. This includes everything from design and production to shelf life, real usage, and finally disposal.
Even large devices with replaceable parts need a certain lifetime. On the other hand, Software devices do not wear out physically, but they require updates, part replacements, and repairs to keep up with new technology and continue to be used safely.
Implantable devices come with their own challenges. Sometimes they can stay in the body longer than expected, especially if you are young. For example, a coronary stent with a presumed lifetime of 10 years can remain in a young person for much longer. This may mean we need more information to ensure it is safe, or it may need additional monitoring after being released to the market.
There are also devices that behave differently inside the body. Some can stay longer or be absorbed at different rates. These factors are important when calculating how long they will remain effective and safe.
For previously used devices, the manufacturer may already have information on how they will perform after a certain period of use.
Let's take a closer look at these devices.
Active Devices:
Active devices have a specific lifetime, and manufacturers must perform various checks to ensure the safe and effective operation of the device. These checks include factors such as material quality, shelf life, risk of breakage, and maintenance frequency. Additionally, manufacturers must calculate the probability of failure of a part of the device, plan repairs, and conduct tests to ensure ease and safety of use. These measures are necessary to ensure the long-term reliability of the devices and provide protection against unexpected uses.
Software:
Medical software needs a planned continuity and security plan. Users should be aware of how long the software will last and the possible risks. Solutions should be found if the software changes or the systems it operates on become obsolete. Plans should be made for parts that are not updated or come from unknown sources. Software security, compatibility, and suitability for new technologies, especially intelligent technologies like artificial intelligence, should be ensured. Manufacturers must keep up with the latest technology and make efforts to keep the software up to date. After all these measures, it is important not to forget the software once it is produced and to keep it continuously updated.
Implantable Devices:
The safety of implantable devices should be considered not only for a specific performance period but throughout the entire duration they are within the body. While medical devices may typically have a performance target of around ten years, they can remain in the body for much longer. Manufacturers must control factors such as materials, quality, duration of stay in the body, and power source to ensure that these devices are safe and effective. Additionally, they should track data to confirm whether the device meets the user's needs and remains safe even in the real-world scenarios. These measures are crucial to ensure the long-term reliability of implanted devices.
Biological Devices:
Biological devices are specialized devices containing drugs or substances that can affect bodily functions. The performance of these devices differs from typical devices because they can have an effect on the body for a certain period. The durability of biological devices is generally related to interactions with the body and changes over time rather than a specific number of years. Manufacturers should ensure the safety and effectiveness of the device by controlling factors such as materials used, duration of stay in the body, and mode of interaction with the body. They should conduct necessary checks to ensure that these devices do not harm the body and do not pose unacceptable risks while performing their functions. It is important to monitor the effects of these devices on the body and any changes after they are released into the market due to their close interaction with the human body.
How should they be monitored after entering the market? (Clinical Data)
Medical device manufacturers should regularly review the performance of the devices they manufacture after they are released into the market. While this monitoring process may be less for common and reliable devices, it requires more careful monitoring for complex or new devices. Special plans should be created for long-term performance monitoring, especially for implants or advanced devices, and this is often referred to as the PMCF (Post Market Surveillance Follow-up) plan. This plan aims to identify new issues that may arise due to the long-term use of the device. Data obtained from PMCF studies are included in periodic safety update reports that regularly update the status of the devices. MDCG 2022-21 provides requirements for periodic safety update reports. Among these requirements, device lifetime, clinical evaluation plans, and reports are considered fundamental data.
Statistical Data
Statistical methods used to monitor the durability and reliability of a device are commonly used to examine post-market surveillance data. These methods typically include techniques such as Weibull, HALT, or HASS. Manufacturers can use data from similar devices in addition to their own to analyze trends. However, when using these statistical methods, manufacturers should ensure that these methods are reasonable and appropriate for the device. They should consider factors such as the reliability of the test methods, including both numerical and other factors, and the significance of the failure rate for the type of device. All of these evaluations should be consistent with the risks and expected service life of the device. However, it is important to remember that the absence of evidence of something going wrong does not mean that there is no possibility of it happening. Therefore, manufacturers should always be cautious and continuously monitor their devices.
