Choosing the Perfect Term: A Comprehensive Guide to Shelf Life, Estimated Lifespan, and Device Lifecycle in Medical Devices & IVD

In the world of medical devices and in-vitro diagnostics (IVD), precision and clarity are paramount. Yet, navigating the terminologies associated with product longevity can be a maze of uncertainty. This guide aims to shine a spotlight on the crucial distinctions between 'Shelf Life,' 'Estimated Lifespan,' and 'Device Lifecycle.' We'll journey through the regulatory landscapes and unveil when and how these terms should be judiciously employed, ensuring compliance with rigorous medical device regulations. Buckle up as we embark on an illuminating exploration of these concepts, demystifying the complex realm of product longevity in the ever-evolving domain of medical devices and IVD. 

Shelf life is the recommendation of time that products can be stored, during which the defined quality of a specified proportion of the goods remains acceptable under expected (or specified) conditions of distribution, storage and display.

Shelf life depends on the product's ingredients, packaging, and storage conditions. For example, a properly sealed and stored reagent can last a certain amount of time without degrading in quality.

Expiry date is based on the shelf life. For example, an opened reagent can last a certain amount of time before it needs to be disposed of.

Shelf life is the period from manufacturing date to expired date.

• Lifetime is first date of use until the product stops working (due to age, wear & tear, etc.).
• Lifecycle is Shelf life + Lifetime.
• Expiration Date is the date the product stops working.

Expected Device Lifetime

It is a period during which the device is intended to perform its function per the risk and benefit profile of a medical device, and maintain its benefits without adding an incremental risk to the patient.” Overall, the expected medical device lifetime may fall within the intended use as specified in the cases listed below;

• Case - 1: The lifetime of devices that are intended to be used only for a specific period (i.e. catheters to deploy a stent) is defined based on their use duration.
• Case - 2: The lifetime of devices that are intended to fully replace a body function (i.e. a joint in the human body) would be ideal for the rest of the patient’s lifetime. It is acknowledged that state-of-the-art devices for the intended use may have a finite service life and may need to be removed/replaced based on physician follow-up and evaluation.
• Case - 3: The lifetime of devices that are intended to function in the body for a limited time (i.e. absorbable implants) is defined by their therapeutic lifetime, their function plus the remaining time to absorption dwelling in the human body.
• Case - 4: The lifetime of devices that have a temporary function in the human body (i.e. implants for bone healing or non-absorbable sutures), is defined by their function in the human body up until the point of removal.

It is essential to understand that the lifetime of a medical device may or may not be based on a single element. Instead, it is a combination of multiple characteristics to carefully identify the safety duration.

Factors Helps to Determine the Device Life

1. Reliability/Durability Testing

Reliability testing is a critical component that directly resonates in defining device lifetime. Reliability testing is the time duration during which a device is tested to several cycles or periods of use of the medical device, based on real-life testing of the medical device. Review bench test verification and durability testing conducted based on relevant standard(s) to evaluate the performance of the respective medical device to assure the product/system design will conform to user needs, given the use environment (in-vitro data).

Fatigue testing is performed as a reliability and durability measure. It is the process of applying cyclic loading progressively leading to a permanent structural change occurring in a material subjected to relevant conditions that produce fluctuating stresses and strains at some points and may affect the product after a sufficient number of cycles/fluctuations. It isn’t necessary to have an infinite number of cycles to cause the structural damage, instead it will be based on the standards recommended for the type of classification and usage of the device.

2. Clinical Performance

The clinical performance attributes define the clinical significance of the device and provide clinical results confirming the findings from the bench test. It includes confirmation to support the performance attributes of the device., patient outcome, etc. Depending upon the device classification, clinical performance validates the bench testing and asserts the expected medical device lifetime.

Evaluate the performance and safety of the device through clinical literature, investigations, pre-clinical assessments, ongoing studies, etc., for the intended clinical use of the device.

3. Residual Risk

The risk management process involves the evaluation of residual risk over the life of the product. The benefits are compared to the residual risks to ensure risk acceptability is justified. Refer to details on the risk assessment and benefit/risk acceptability conclusion for this product.

When determining the appropriate expected device lifetime, it is important to consider whether certain risks are introduced for certain phases of the potential product lifetime—and whether those risks are acceptable or appropriate to discontinue use of the product to avoid the risks. The risk considerations pertinent to the expected device lifetime for this product are described below.

Example: This product has been tested for reliability performance out to five years. Beyond five years, the potential for increased residual risk due to product failures has been considered; however, this risk is deemed acceptable due to the product performance monitoring and associated corrective actions process, which may be used to address unexpected increases in patient risk.

Clinical evaluation: The decision to use a medical device in the context of a clinical procedure requires the residual risks to be balanced against the anticipated benefits of the procedure. Explain the device's clinical performance and benefits, the circumstances of use, and why it outweighs the risks. Evaluate the medical device performance attributes affirm its integrity; utilize clinical studies to supplement the justification.

Also, evaluate if any characteristics related to degradation of the clinical performance of a medical device can result in unacceptable risk to essential performance.

Post-market surveillance: If applicable and available, utilize post-market surveillance information to support how the observed performance is within the predicted performance defined in the risk management plan/report. If any indicators observed during the commercial history of the product or any significant or critical risk currently present in the field, provide an in-depth evaluation of why the risk is acceptable over the expected device lifetime.

4. Shelf Life/Expiry Date Of The Medical Device

The shelf life ends with the first use of a device, for example, when its packaging is opened (e.g., dental filling materials for several portions across multiple uses). The shelf life is particularly important for sterile devices that must remain sterile until first use, including during transport and storage. In this case, the manufacturer specifies for how long sterility is assured under specified conditions.

The term “stability” is generally used to describe a device characteristic. The manufacturer must provide evidence of stability for both the shelf life and the lifetime. Since a medical device's safety and performance can also be impaired after the device's first use, from this point until the end of the device's lifetime, we use the term in-use stability (e.g., for dental filling materials). A device's lifetime starts at the time of production and, therefore, includes the shelf life;

• Lifetime (or service life): Total period of time from production to the end of a device's life during which the device is safe and performs as intended
• Shelf life: Maximum period of time between production and commissioning/use during which the device is still safe and performs as intended
• Stability: Device property indicating that the device remains safe and performs as intended throughout the device’s life cycle
• In-use stability: Time between commissioning/opening of packaging and end of life

Additional factors to be considered for shelf-life determination;

Material degradation: An expiration date is the termination of shelf life, after which a medical device may no longer function as intended. Degradation or anticipated degradation is the established timeline after which the product or component is expected to decline in quality or effectiveness. To determine if a device requires an expiration date, several different parameters must be considered. The device must be analyzed to determine if it is susceptible to degradation that would lead to functional failure and the level of risk that the failure would present. Assess if the medical device in scope depends on certain component characteristics or expiry date; this assessment is used to determine the overall expected medical device lifetime.

Packaging stability: The stability of packaging material is the extent to which a product within it retains as is, within specified limits, and throughout its period of storage and use. It is the established period that the product has been validated to meet all predetermined design, quality, and effectiveness requirements.

Sterility assurance: Sterility assurance is a crucial component in determining the safety of a medical device. Sterility should be maintained during the entire period of transportation, storage, and use. The level of cleaning and disinfection needed depends on the use of the device. All reusable devices need to be able to clean at some level, and that level depends on the risk of the device. Single-use devices must maintain the sterility level for the expected lifetime of the device. Depending on the device's usage, the device's sterility could impact the expected safe use of the device, thus defining the lifetime.

Cleaning and disinfection: Cleaning and disinfection are factors that are frequently overlooked when determining the product lifetime. Use of the product may involve cleaning and disinfection. The cumulative effect of heating or drying procedures and chemical residues from such procedures can affect the product’s performance and should be assessed in terms of the effects on the product lifetime.

Different sterilization methods (steam sterilization, ethylene oxide sterilization, radio sterilization, etc.) and packaging methods can also have different effects on the product lifetime. Therefore, for example, the effects of the sterilization procedure (methods and parameters) on the product lifetime should be considered.

Examples

• An implant may have a lifetime of 15 years (including time in the human body), but a shelf life of only 2 years in terms of stability in its original packaging
• A substance-based medical device may be stored in its original packaging for three years (shelf life) but have to be used within 12 months of being opened (in-use stability)

Ways of extending the lifetime

For each component, the materials and operating principles must support the required lifetime. If this is not possible, the following options can guarantee the component lifetime and minimize risks:

• Maintenance: Manufacturers can allow for preventive replacement of components. In this case, the corresponding maintenance intervals must be included in the instructions for use (IFU).
• Test function: Alternatively (or additionally), manufacturers can implement a test function on the product that reliably detects component failure (or other safety and performance limitations). This is always an option if the test function makes the product safer. However, it also means that this option is not effective in the case of life-sustaining/life-support systems. If their performance is limited or they malfunction and the test function is triggered, it is already too late.

Regulatory requirements for the lifetime of medical devices

Within the intricate web of medical device regulations, the concept of a device's 'lifetime' occupies a pivotal position. However, it's a terrain where clarity often eludes due to the absence of comprehensive, overarching legal regulations. Rather, the regulatory framework involves the meticulous oversight of individual facets that collectively shape the journey of a medical device. These include:

• Full refurbishment and effect on lifetime: Rather than focusing solely on how refurbishment affects a device's "Shelf Life," regulatory considerations now extend to how it influences the "Estimated Lifespan." Understanding the implications of refurbishment processes on a device's functionality, safety, and longevity becomes paramount. Regulations may stipulate guidelines for refurbishment procedures, ensuring that they align with the expected Estimated Lifespan.
• Labeling of lifetime: "Labeling" is essential for conveying information about a medical device's safe and effective use over time. Manufacturers must provide clear information on a device's Estimated Lifespan, rather than the traditional "Shelf Life" duration. Proper labeling educates healthcare professionals, patients, and users about how long they can rely on the device before considering replacement or servicing.
• Quality management system and lifetime: Robust Quality Management Systems (QMS) are fundamental in preserving a device's quality and longevity. Compliance with QMS standards now directly influences the Estimated Lifespan of a device. Manufacturers adhere to comprehensive processes encompassing design, production, and continuous monitoring, ensuring the device's sustained performance throughout its Estimated Lifespan.
• Communication of the lifetime: Effective communication within the healthcare industry pertains to the Estimated Lifespan of medical devices, rather than the traditional concept of "Shelf Life." Clear and accurate information in product documentation, labeling, and marketing materials ensures that healthcare professionals, regulatory authorities, and users comprehend how long a device can be safely and effectively utilized.
• Active medical devices and lifetime: Some medical devices fall into the category of "active" devices, relying on power sources or electronic components for functionality. For these devices, the Estimated Lifespan considers factors such as battery life, component durability, and software updates. Managing the Estimated Lifespan of active devices is crucial to uphold patient safety and device efficacy.

While regulations often mandate the inclusion of 'Shelf Life' and 'Expiry Date' for medical devices, it's crucial to recognize that these terms may not be universally applicable. Certain medical devices, by their very nature or intended use, may not conform to the traditional concept of 'Shelf Life.' In such cases, the term 'Estimated Lifespan' emerges as a more fitting and accurate alternative.
The term 'Estimated Lifespan' transcends the constraints of traditional shelf life definitions and aligns with the unique requirements and characteristics of these specialized devices. It serves as a reminder that not all medical devices adhere to standard expiration parameters and underscores the need for a tailored approach to define their operational longevity.

Conclusion

The safety and performance of a medical device are assured only within the boundaries of its specified lifetime. It's essential to consider all factors that influence risk when determining this critical parameter. However, the realm of medical devices is not immune to certain misconceptions and misinterpretations surrounding these terms. Some manufacturers and operators, at times, exploit the inherent vagueness in these definitions to their economic advantage.

Terms such as "lifetime," "shelf life," "end of service," "operating time," and "end of life" are not interchangeable synonyms. Each term holds distinct significance within the regulatory framework. To navigate this complex landscape effectively and ensure compliance with stringent regulatory requirements, it's imperative to grasp the precise meanings and implications of these terms. A nuanced understanding is the key to upholding the highest standards of safety, performance, and ethics within the realm of medical devices.