How to improve the design of medical device IFUs

Instructions for Use (IFUs) can be a fundamental asset to the safe and effective use of a medical device. Central to this is that instructions are usable for the intended user and that it provides the user with information to use the device as it was intended within the intended environment. EU Regulation 2017/746 states that ‘instructions for use shall be appropriate to the particular device, its intended purpose and the technical knowledge, experience, education or training of the intended user(s)’ and that ‘instructions for use shall be written in terms readily understood by the intended user’.

However, what does this mean in practice and what insights can be drawn from usability studies on medical devices?

Through our experience of conducting usability studies here at THAY Medical, we found that some elements that contribute to the design of IFUs have an impact on their usability. Therefore, to help answer this question, it is useful to identify a few of these elements:

·        Language used

·        Content

·        Layout

·        Use of diagrams

·        Format of text

·        Sequencing of tasks

The next step is to understand how these design elements impact on user behaviour. Here are just a few of our insights here at THAY:

Language used – Not surprisingly, the terminology and language used in IFUs need to be representative of the language and terminology used by intended users. It is worth listening to how users reword instructions in IFUs and the language they use when discussing tasks. For example, we found that ‘the hand that you write with’ were more understandable for younger users than ‘your non-dominant hand’.

Content – Information in the IFU needs to be accurate. We found that if there are inconsistencies between the information on the IFU and device components several use errors can be traced back to these.  It is interesting how easily this aspect of an IFU design can be overlooked. The following aspects are worth noting:

·        The list of components on the IFU needs to be the same as the physical components of the device that the user will interact with.

·        Consistency in the wording of the IFU is important. For example, names of components in the IFU should stay consistent throughout to reduce use errors.

·        The diagrams used in the IFU to represent the device components need to be an accurate representation of that of the device.

Layout – How information is presented had an impact on successful task completion. Here are some insights related to layout:

·        In our studies, we found that a significant number of participants tend to start reading instructions at the point where instructions related to the operation of the device start on the IFU. They therefore skipped over preparatory information and instructions. This means that information and instructions can easily be missed. It is suggested that any relevant tasks are added to the task instructions rather than placed into a preparatory section on the IFU.

·        Similarly, studies have highlighted that images and pictograms in an IFU direct users attention. Users frequently miss steps because they follow the sequence of the images. It is suggested that important information should be paired with an image.

·        Another interesting insight is that if an instruction contained more than one task, even if the task is related, a number of participants would not complete the second task and report that they did not see it. Therefore, ideally, each step in the instructions should only relate to one task.

·        Further, numbering instructions tend to improve task completion versus, for instance, using bullet points.  

Format of text - If text sizes are too small, it impacts on the willingness of participants to read the instructions. We found that some participants would skip reading the instructions if the text were too small and instead just look at the diagrams for guidance on how to perform tasks.

Sequencing of tasks - The sequence of the tasks to be performed is important in the usability of the IFU. For instance, in some studies use errors were a result of users juggling multiple different components at the sample time. In this case, a simple reordering of tasks would have averted the problem.

You might ask, how do I ensure I fulfil all these areas when designing my IFU? Here is a list of initial questions that are useful to ask when looking at the design of an IFU:

·        Is the terminology used in the IFU understandable for the intended user?

·        Is the list of medical device components in the IFU the same as the physical components?

·        Are the diagrams an accurate representation of the device or components of a device/kit?

·        Is there only one task per instruction?

·        Are the tasks numbered on a step-by-step basis?

·        Are important tasks part of the step-by-step instructions section on the IFU?

·        Is the text size easily readable by a range of the intended users?

·        Are the tasks logically sequenced?

·        Are tasks sequenced in a way that means that users do not need to perform several tasks at the same time?

Guidance and regulations related to the information above:

EU Regulation 2017/746 and 745

FDA – Applying Human Factors and Usability Engineering to Medical Devices