Whilst the Medical Device Directive (MDD) had a few mentions of the word “usability”, it was not back in 1993 when it was written, a commonly used term. More often, it was the term “ergonomic” that was used, and this word did make a few appearances in the Essential Requirements (Annex I) of the 1993 Medical Device Directive. The new Medical Device Regulation released recently now appears to have more of a focus on “usability” and “ergonomics”, in the context of risk management, which reflects the existing trend towards more effective, human-focused, comprehensible, safe and easy to use medical devices.
In this blog, I shall review the new Essential Requirements of Annex I of the Medical Device Regulation and discuss points specific to “usability”, “human factors” and “ergonomics” so that there is a clearer understanding that adherence to these new regulations means performing an element of usability engineering and human factors. In addition, since there are a number of areas to cover, this article is in two parts.
Chapter I – General Requirements
“Devices shall achieve the performance intended by their manufacturer and shall be designed and manufactured in such a way that, during normal conditions of use, they are suitable for their intended purpose. They shall be safe and effective and shall not compromise the clinical condition or the safety of patients, or the safety and health of users or, where applicable, other persons, provided that any risks which may be associated with their use constitute acceptable risks when weighed against the benefits to the patient and are compatible with a high level of protection of health and safety, taking into account the generally acknowledged state of the art.”
This requirement discusses ensuring the performance intended for the medical device covers the “safety of patient, or the safety and health of users or, where applicable, other persons”. This is an interesting phrase as it expands from just the “user” to “patients” – recipients of the performances of medical devices, but also “other persons”. This we interpret as other people who interact with the medical device – an example would be a prescriber (consultant) or biomedical engineer or cleaner (interact, maintain, but do not use the medical device). This means that defining between “users” and “other persons” should be defined during the medical device development in theory, then evaluated in practice during later development and post-launch to ensure the theory was correct in the first place. The usability engineering standard IEC 62366-1:2015 asks this to be performed in a Use Specification. Knowing who will use and who will interact with the medical device constrains the limits for design, development and testing, and so can guide the development to focus on the users, patients and other persons – critical for when evaluating for use safety.
“In carrying out risk management, manufacturers shall: c) estimate and evaluate the risks associated with, and occurring during, the intended use and during reasonably foreseeable misuse.”
This requirement focuses on usability risk assessment “during the intended use and during reasonable foreseeable misuse”. Here, the manufacturer is asked to assess use-based risks. On the surface this is a straight-forward activity, based upon compliance to ISO 14971:2012 – a usability risk assessment should be the output. But where compliance to the usability engineering standard IEC 62366-1:2015 is required, then a more in-depth understanding of hazard related use scenarios is required. To understand use error, and then to risk assess it, the manufacturer needs to understand the situation that the use error arises within, and is seen within. By doing this, the manufacturer can determine root causes as to why the use error arises in the first place – did it occur due to a perceptive error, a cognitive error or an action-based error. This is called “PCA” analysis and is commonly used nowadays. By understanding what part of the body is interacting with the medical device and creating the use error, the mitigation can be more tailored to minimise it occurring in the future.
“In eliminating or reducing risks related to use error, the manufacturer shall: a) reduce as far as possible the risks related to the ergonomic features of the deice and the environment in which the device is intended to be used (design for patient safety), and b) give consideration to the technical knowledge, experience, education, training and use environment, where applicable, and the medical and physical conditions of intended users (design for lay, professional, disabled or other users).”
This requirement is very “human factors” focused. It is specifically stating that the manufacturer shall reduce risk due to “ergonomic features” and to give consideration to human factors such as “technical knowledge, experience, education, training, the use environment and the medical and physical conditions of the intended users” – be they professional, lay, disabled or other users”. This again, is part of the usability engineering standard IEC 62366-1:2015, and included in the US FDA Human factors guidance in requirement. It is the definition of the intended users and interactors – the Use Specification of a device. The purpose is to ensure that the human factors surrounding the users are defined and understood – the influencers of how, why, when, what and where the interactions take place.
This requirement also serves a purpose in ensuring the medical device is designed with the users understood – especially their capabilities and limitations, both mentally and physically. For example, designing a device for older people with dexterity (aging) issues, may need an understanding of what could limit them from using it safely. How many of the population are likely to have aged-related diseases and conditions (Alzheimer’s, Arthritis, Cancer etc.), and how would this affect the intended use of the device. Does it mean the concept or design has to change to enable safe use?
Often to understand and to determine these considerations, user research is performed. The most frequent method of gaining this understanding is to talk to people – interview them, interact with them; and if this is not enough, perform ethnographic studies and contextual enquiry to observe them in action. Additional user research includes using the internet, reading books or magazines, reviewing scientific literature or historical data (customer complaints, adverse incident data etc.).
“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, as 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.“
This requirement details ensuring that the medical device does not adversely affect the “health or safety of the patient of the user and, where applicable, of other persons”, and also “during the lifetime of the device”. This is common-sense, but is less straight-forward to prove during development, and a lot easier post-launch (although not for a while in some cases!). One good method of assessing this requirement is to perform usability evaluation – in a usability study. Within this study, the lifetime of the use and interaction of the device can be simulated – and therefore assessed in a theoretical manner at least, before launch. It is not just about compliance though to the Medical Device Regulation – we at THAY Medical recommend that usability evaluations generate confidence in the abilities of the medical device to be safe for its users and interactions. In this context, to know how intended users are likely to use the device near the end of its life, or in a specific situation, and to know it is still safe is valuable data to have. This requirement also is about recording the risk in the usability risk assessment in its intended use.
“Devices delivered in a sterile state shall be designed, manufactured and packaged in accordance with appropriate procedures, to ensure they are sterile when placed upon the market and that, unless the packaging which is intended to maintain their sterile condition is damaged, they remain sterile, under the transport and storage conditions specified by the manufacturer, until that packaging is opened at the point of use. It shall be ensured that the integrity of that packaging is clearly evident to the final user.”
This requirement discusses the design, manufacture and packaging of sterile medical devices, and in particular, the integrity of the sterility during transport and storage conditions. It states very specifically that “it shall be ensured that the integrity of the packaging is clearly evident to the final user”. This means that there must be a way the user can determine the sterility of the device when they come to interact with it. This is frequently done by labelling, but should be proven through usability evaluation if possible – again data is more powerful in risk management than theory. Evaluation of the risk of compromised sterility in a sterile device and in packaging can be assessed in usability testing.
Part 2 to follow next week…
If you have any questions, please do not hesitate to contact THAY Medical. We would love to hear from you.
The staff at THAY Medical