Determining a device’s potential use errors, a mini-series. Part 1: Understanding the intended user

PUBLISHED 12th February 2018

Medical Device Usability has decided to post a mini-series in relation to understanding different areas of research that feed in to the ‘risk management file’ or the usability failure modes and effects analysis (uFMEA). In part 1 of this mini-series, we will discuss the intended user and how they relate to determining use errors.

The intended users for a medical device are known soon after the device itself has been established as a viable concept, however our experience is that formative testing can uncover new users that were unanticipated by the manufacturer. The more components included in normal use of a medical device or the more intricate the system of use the more likely there will be secondary (or tertiary) users that may only interact with small elements of the system, but nevertheless they are essential for safe use.

Early formative testing with the known users is the best opportunity to uncover the true breadth of user groups. For example – it may be assumed that a physician would prepare a site on a patient’s body prior to some device being implanted, however it may actually be a nurse. The five physicians you recruited may all say ‘no difficulties preparing the site’ when actually five nurses would tell a very different story. ISO standard technical report 62366-2 outlines that all distinct user groups need to be represented in a validation study, it is most cost effective to understand who these groups are early. Some study designs that can be utilized to investigate who the intended users are include;

Expert review – The HF consultant who is a part of the design process may have experience with similar devices and therefore be able to provide insight into the nuances of the tasks involved with use of a device and peripheral components.

One-to-one interviews – Given the right style of questioning and design of a study to incorporate all aspects of use (regardless of the existence of a task list at the point of interviewing) a moderator may be able to gather data on the true users of particular peripheral items or processes.

Once the intended users have been established, user profiles need to be created. A user profile in the context of design is not the same as a user profile in the context of usability. FDA guidance UCM259760 provides this list of example characteristics that need to be considered;

  • Physical size, strength and stamina
  • Physical dexterity, flexibility and coordination
  • Sensory abilities (i.e. vision, hearing, tactile sensitivity)
  • Cognitive abilities, including memory
  • Medical condition for which the device is being used
  • Comorbidities (i.e. multiple conditions or diseases)
  • Literacy and language skills
  • General health status
  • Mental and emotional state
  • Level of education and health literacy relative to the medical condition involved
  • General knowledge of similar types of devices
  • Knowledge of and experience with the particular device
  • Ability to learn and adapt to a new device, and
  • Willingness and motivation to learn to use a new device

The user profile will be a key component in determining potential use errors relating to the user. Outlining the intention to investigate the user early in the design process and regularly as the device is developed will allow for the user profile to contribute to design characteristics.

For more information, please don’t hesitate to contact us! The next installment will be titled; ‘Considering the intended use environment’.



  1. International Electrotechnical commission Technical Report 62366-2:2016, Medical devices – Part 2: Guidance on the application of usability engineering to medical devices
  2. Food and Drug Administration, Center for Devices and Radiological Health UCM259760, Applying Human Factors and Usability Engineering to Medical Devices.