Sep 29, 2020

Several amendments to the text of the international standard IEC 62366-1: Application of usability engineering to medical devices have been published in June 2020. This standard drives much of the usability engineering work done by Emergo by UL’s Human Factors Research & Design (HFR&D) team. There are a large number of changes, some small and some more significant. The key changes that will affect usability engineering (UE) methods are as follows:

Key changes to IEC 62366

Reference to risk management: Updating of the reference to ISO 14971 with the standard’s 2019 version. So in effect, this means that manufacturers should follow the 2019 version of ISO 14971.

Definition 3.22: Use scenario: Introduction of the term “critical task” as one for which a use error could lead to significant harm (i.e., aligning with US FDA use of the term “critical task”). Note that this term has not been included in IEC 62366’s formal list of definitions. But, it is an important inclusion nonetheless.

Definition 3.25: User group: The definition has been rewritten to emphasize that user groups are subsets of users who are differentiated by “factors that are likely to influence their interactions with the medical device.” Although the standard does not provide any examples, we know from our experience that factors such as professional status (e.g. lay user versus healthcare professional), age (e.g. child versus adult), and disease type (e.g. asthma versus COPD) are likely to define distinct user groups.

Types of use: Types of use are mapped, and the corresponding scope of ISO 14971 and IEC 62366 are overlaid to illustrate how both standards should be applied according to the type of use. The following types of use are mapped:

  • Reasonably foreseeable use – normal and abnormal. Normal use is further divided into correct use and use error, whilst abnormal use is depicted as “outside of scope” for 62366
  • Not reasonably foreseeable use.

The new text re-confirms that abnormal use is outside the scope of IEC 62366 but within the scope of ISO 14971, a useful distinction.

Risk control measures (section 4.1.2): Training has been introduced as a third priority control measure, alongside information for safety.

Summative evaluation (section 5.7.3): This introduces a number of new requirements concerning summative evaluation to:

  • Explicitly state how the participants in the summative evaluation are representative of the intended user profiles. This underlines the importance of involving representative users in the evaluation.
  • Describe how the test environment and conditions of use are adequately representative of the intended use environment.
  • Define correct use for each hazard-related use scenario ( we think this is an important addition because it should be used to define success and failure for each task that is evaluated).
  • Describe how data will be collected during the test.

Summative evaluation acceptance criteria (subclause 5.7.3 Summative evaluation planning): This has been removed and in its place is a clarification that the purpose of the summative evaluation is to gather objective evidence that the residual use-related risk is acceptable. With the added requirement for defining correct use for each use scenario evaluated, this means that the ”success” or “failure’ of summative evaluation is directly measured by the extent to which use-related risk is avoided.

Action errors: The previous version of IEC 62366 used the term “action error” to describe a use error caused by some aspect of the physical limitations involved in performing a task; in the new version the term has been replaced by “physical mismatch.” Note that this is slightly different from FDA’s term “physical actions,” and encourages us to think about any mismatch between the capabilities required to perform a task and the physical capabilities of the user.


In summary, the 2020 amendment to IEC 62366 includes several changes that impact various UE activities, as well as an updated linkage to the newest version of ISO 14971.

Richard Featherstone is Research Director and Natalie Shortt is Senior Human Factors Specialist at Emergo by UL’s HFR&D division.

Additional IEC 62366 and human factors engineering (HFE) resources:

  • HFE user research support for medical devices, IVDs and combination products
  • Human factors analysis for medical devices
  • Webinar: Meeting US FDA expectations for HFE activities
  • Whitepaper: Residual risk analysis of user interaction problems


  • Richard Featherstone and Natalie Shortt