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Human factors and usability are becoming more and more prevalent in the design and development process. So much so, that many organisations are placing a focus on the human factors element of their product development. But, is it a necessary inclusion or simply an added benefit?

At eg technology, we live and breathe integrated end-to-end development. So, for us, the answer is simple. Human Factors and usability engineering cannot be shoehorned or retrofitted into a design programme, they are an integral process and drive insight-led, effective product development. But what is the difference between human factors and usability?


They are essentially the same thing. The FDA tend to use the term human factors, whereas usability is more prevalent in European programmes. However, the actual definition from BS EN 62366 is “Characteristic of the user interface that establishes effectiveness, efficiency, ease of user learning and user satisfaction”. Usability is about gaining a deep understanding of how the product is used and the context in which the user interacts with the product across its life cycle. This means gaining full insight on the users, user tasks, the user interface, use scenarios and use environment early on in your development. Considerations need to be made around what factors may impact the user interaction with the product; for example, if your product UI relies on red and green images, then it will be prohibitive for someone who is colour blind or if the screen is highly reflective, then bright lights in a surgical environment may cause glare, making the screen difficult to use. It is therefore key to ensure you utilise your user testing to challenge your design assumptions.


Humans are fallible and poorly designed UI can lead to error and potential harm. An example of this was the UI of a blood glucose monitor, on which the decimal point, separating numbers, was difficult to decipher. The consequence of this was at home patients misreading their blood glucose levels as 22mmol/L as opposed to 2.2mmol/L and therefore administering a much larger dose of insulin than was required, leading to diabetic coma. This shows how a small usability oversight can have catastrophic consequences.

Problems such as these are actually becoming increasingly problematic, as at home devices become more prevalent, increasingly complex and operated by unskilled users. Clinicians are also having to deal with an increasing number of devices with complex or conflicting user interfaces. This is why it is critical to engage users as early into the development process as possible. The sooner any issues are identified, the sooner the risks can be mitigated and changes incorporated. The benefits of this are not only from a safety point of view, but also commercial. A demonstrably safe, intuitive and effective product that has been developed with the user, will be less likely to receive negative client reviews, fewer recalls and have fewer associated training costs.


Early user input will force you to challenge assumptions. By considering all potential use scenarios, you can then factor them into your development and design out any potential errors, early. User expectations have shifted with the prevalence of wearable devices, especially as many now have the appearance of being ‘medical’ – such as health trackers. Users, therefore, have an expectation as to how the UI should look, feel and operate, as well as how the device itself looks, how it charges and how it fits into their daily lives. This expectation is obviously dependent on the situation in which the device is used, and by whom, but as consumer devices evolve, medical UIs are expected to assimilate.

User studies should therefore allow you to manage expectations and challenge assumptions within your development. When we were working with CFT, the general assumption was that the device should be entirely handheld and portable, but with user insight, we soon realised that in an A&E environment, that handheld wasn’t the best option. Without user and situational feedback, we would have continued with a development that would have yielded a product that was not suitable and would therefore have caused costly redesigns. This consultation process not only mitigates financial impacts but can actually provide a competitive edge within the market, as your device will be something that users need and want! Check out the full CFT case study here to look at the full development process.


IEC 62366 is the recognised standard for managing use risks. With the recently implemented MDR and the forthcoming IVDR in May 2022, more emphasis has been placed on usability. The process for each is similar, with the overarching requirement being that you demonstrate your device is both safe and effective for use, in the intended situation, by the intended user group.

Considerations need to be made regarding the device’s potential for harm, whether it will be used by laypeople and whether the UI is complex or novel to the user. The scale of development work, therefore, needs to be relevant to the scale of risk. By demonstrating you have not only planned but also implemented the integration of human factors or usability studies into your development, you are on your way to achieving compliance. Of course, with usability spanning the entire development, traceability is key and being able to provide the required documentation and ensuring usability feeds into your final engineering file, you should be on track for developing a final product that is not only safe and effective to use but also market-ready and compliant to the required usability standards and regulations.

In part two of Human Factors and Usability Engineering – a “must” or a “good to have”, we will be looking at the key stages within the usability process and where it sits in your overall product engineering design and development roadmap. Click here to subscribe to our blog and receive this content directly to your inbox.

For further information on how eg technology can support the Human Factors integration of your product development, please get in touch.

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