Expected lifespan of medical devices at a glance
The life expectancy of medical devices is currently a hot topic in the industry, given the requirement of the European Medical Device Regulation, EU MDR 2017/745, Article 18 1 (c). Article 83 Post-market surveillance, Article 86 Periodic safety update report, Annex XIV part B – Post-market clinical monitoring is also linked to the expected lifespan of the device. Manufacturers are required to provide a defined expected life for certification of their product under the new European medical device regulations. There has been a lot of discussion about how best to define the expected lifespan of the device and what to consider when defining it.
Define the “expected lifespan” of a medical device
Let’s take a look at the definition of expected device life. “This is a period during which the device is intended to perform its function in accordance with the risk and benefit profile of a medical device, and to maintain its benefits without adding additional risk to the patient. Overall, the expected life of the medical device can match the intended use, as specified in the considerations listed below (MedTech Europe Paper).
Consideration 1: The lifespan of devices intended to be used only for a specific period (i.e. catheters for deploying a stent) is defined by their duration of use.
Consideration 2: The lifespan of devices intended to entirely replace a bodily function (i.e. a joint in the human body) would be ideal for the remainder of the patient’s life. It is recognized that advanced devices for the intended use may have a limited lifespan and may need to be removed / replaced depending on physician monitoring and evaluation.
Consideration 3: The lifespan of devices intended to function in the body for a limited period of time (i.e. absorbable implants) is defined by their therapeutic lifespan, their function plus the time remaining until absorption. in the human body.
Consideration 4: The lifespan of devices which have a temporary function in the human body (i.e. implants for bone healing or nonabsorbable sutures), is defined by their function in the human body up to the point of withdrawal.
Each consideration listed above could include many elements, which are explained in this article. It is essential to understand that the lifespan of a medical device may or may not be based on a single element. Instead, it is a combination of several characteristics to carefully identify the safe duration. Items include patient outcomes, product design, clinical utility, observed product performance, benefits and risks including positive / negative impact on clinical outcome, patient quality of life , diagnostic outcomes and the positive / negative implications of diagnostic devices on clinical outcomes. There are external factors that could contribute such as patient anatomy, disease progression. Depending on the extent of the external factors, there may not be a specific duration based on bench testing; therefore, for advanced medical devices, manufacturers must consider the actual factors and provide the necessary instructions afterwards to establish safe performance.
First, it is imperative to understand the medical device within its scope, which will dictate which elements will apply and align the result accordingly. To begin with, it is necessary to first identify the primary element, which defines at a high level the overall function of the device in the body, followed by secondary supporting elements such as residual risk. Not all items apply to the affected device type. Let’s dive a little deeper into each of these and understand the correlation with device life.
- Reliability / durability tests:
Reliability testing is an essential element that resonates directly in defining the lifespan of devices. Reliability testing is the length of time a device is tested over multiple cycles or periods of use of the medical device, based on actual testing of the medical device. Review bench testing verification and durability tests performed against the relevant standards to assess the performance of the respective medical device to ensure that the design of the product / system will meet the user’s needs, taking into account the environment of use (in vitro data).
Fatigue tests are performed as a measure of reliability and durability. It is the process of gradual application of a cyclic loading leading to a permanent structural change occurring in a material subjected to relevant conditions which produce fluctuating stresses and strains at certain points and can affect the product after a sufficient number cycles / fluctuations. It is not necessary to have an infinite number of cycles to cause structural damage, on the contrary, it will be based on the recommended standards for the type of classification and use of the device.
- Clinical performance:
The clinical performance attributes define the clinical significance of the device and provide clinical results confirming the bench test results. It includes confirmation of support for device performance attributes, patient outcomes, etc. Depending on the classification of the device, the clinical performance validates the bench tests and confirms the expected lifespan of the medical device.
To assess the performance and safety of the device through clinical literature, investigations, preclinical evaluations, ongoing studies, etc., for the intended clinical use of the device.
- Residual risk:
(Note: for implantable devices, the residual risk that results from the entire period of residence of the device inside the patient’s body):
The risk management process involves the assessment of residual risk over the life of the product. The benefits are compared to the residual risks to ensure that the acceptability of the risk is justified. Refer to details on risk assessment and conclusion of acceptability of benefit / risk for this product.
When determining the appropriate expected life of the device, it is important to determine whether certain hazards are introduced for certain phases of the potential life of the product and whether those hazards are acceptable or appropriate to discontinue use. of the product in order to avoid risks. The risk considerations for the expected life of the device for this product are described below.
Example: This product has been tested for reliability performance over five years. Beyond five years, the potential for increased residual risk due to product failures has been taken into account; however, this risk is considered acceptable due to the monitoring of product performance and the associated corrective action process, which can be used to deal with unexpected increases in patient risk.
Clinical evaluation: The decision to use a medical device as part of a clinical procedure requires weighing the residual risks against the expected benefits of the procedure. Explain the clinical performance and benefits of the device, when to use it and why it outweighs the risks. Evaluate the performance attributes of the medical device assert its integrity; use clinical studies to supplement the rationale.
Also assess whether characteristics related to the degradation of clinical performance of a medical device may cause unacceptable risk to essential performance.
Post-market surveillance: If applicable and available, use post-market surveillance information to document how observed performance falls within expected performance defined in the risk management plan / report. If any indicators have been observed during the product’s commercial history or any significant or critical risk currently present in the field, provide a thorough assessment of why the risk is acceptable over the expected life of the device.
- Shelf life / expiration date of the medical device:
Shelf life is typically used to define the expected lifespan of a single-use device. Shelf life is the length or established period of time that a product remains fit for its intended use, as demonstrated by objective evidence. Product shelf life dictates how long you can expect a product to maintain expected safety and performance, measured from the date of manufacture to a validated end point. This duration varies depending on the type of product, its use and storage. Depending on the use of the device, the shelf life may represent the expected life of a medical device or provide the life of a device to function as intended. Additional information is provided below for consideration of the shelf life determination.
Note: The shelf life / expiration date refers to the expiration date. If the device includes an implant, the life of the implant should not be confused with the expiration date of the entire device.
Material degradation: An expiration date is the end of the shelf life, after which a medical device may no longer perform as expected. Degradation or anticipated degradation is the established time period 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 need to be considered. The device should be analyzed to determine whether it is susceptible to degradation that would result in functional failure and the level of risk the failure would present. Evaluate whether the medical device concerned depends on certain characteristics of the component or on the expiration date; this assessment is used to determine the overall expected lifespan of the medical device.
Package stability: The stability of packaging material is the extent to which a product it contains remains as is, within specified limits, and throughout its period of storage and use. This is the established period during which the product has been validated to meet all predetermined requirements for design, quality and effectiveness.
Guarantee of sterility: The assurance of sterility is a crucial element in determining the safety of a medical device. Sterility must be maintained throughout the period of transport, storage and use. The level of cleaning and disinfection required depends on the use of the device. All reusable devices must be able to clean to a certain level, and this level depends on the risk of the device. Single-use devices must maintain the level of sterility for the expected life of the device. Depending on the use of the device, the sterility of the device could impact the expected safe use of the device, thus defining the shelf life.