Human factors (HF) professionals, particularly in the medical device industry, are familiar with the international standard IEC 62366. It covers the “Application of usability engineering to medical devices” and as such specifies usability requirements for the development of medical devices as it relates to safety. The usability engineering process as described in the standard allows the manufacturer to assess and mitigate risks that are associated with correct use and use errors.

IEC 62366:2007 covers usability requirements.

IEC 62366:2007 is a harmonized standard, which means it is a European standard developed by one of the European standardization organizations at the request of the European Commission. Harmonized standards can be used by manufacturers to demonstrate that their products and processes comply with relevant EU legislation. International standards adopted by an international standardization organization can also be harmonized under a mandate. As a harmonized international standard, IEC 62366:2007 can be used as a benchmark to comply with regulatory requirements in both the European Union and the United States.

The most recent usability engineering standard, IEC 62366-1:2015 has not yet been harmonized; however, the Medical Device Regulation (MDR) stated that manufacturers should take in to account the “generally acknowledged state of the art,” which suggests that IEC 62366-1:2015 should be utilized. In June 2020, an amendment to IEC 62366-1:2015 was published. This article identifies the changes made to the standard as well as their potential impact.

Wording Changes

Since its publication in 2015, experts had identified 22 issues that were addressed in the amendment without making fundamental changes to the usability engineering process. As a result, most changes are small wording changes, such as the word functionality being replaced by the word performance, intentional becoming deliberate, and benefits now being called advantages.

Definition Changes

Other modifications include changes in the definition of terms. For example, Unacceptable Risk used to be defined as a use error leading to exposure to direct physical hazards. Now, these hazards are no longer limited to direct physical hazards. Several of these changes are due to the fact that the amendment is aimed at making the standard more compatible with “ISO 14971:2019 Medical devices — Application of risk management to medical devices.”

Selecting Hazard-Related Use Scenarios

One of the most salient changes is how manufacturers are instructed to select hazard-related use scenarios for their summative evaluation. Manufacturers used to be able to make a choice to test either all hazard-related use scenarios, or a subset of hazard-related use scenarios based on the severity of the potential harm that could be caused by use error. Now device manufacturers get a third choice, which is selecting a subset of hazard-related use scenarios based on the severity of the potential harm and based on other circumstances specific to the medical device and the manufacturer.

This new option leaves the manufacturer with a lot of room for interpretation as it is phrased very vaguely. It is unclear what “other circumstances specific to the medical device and the manufacturer” could mean and whether this would add hazard-related use scenarios to the summative evaluation or allow the manufacturer to avoid including certain hazard-related use scenarios even if they otherwise had to be included based on their severity.

Use Difficulty

Additionally, the new amendment includes a definition for Use Difficulty and prescribes the manufacturer to identify not only all use errors, but also use difficulties. The term includes close calls, but also situations in which problems in use have been observed by the moderator or expressed by the participant, but no use error is committed. However, the term is not included in the list of the terms and definitions in Chapter 3 of the standard.

User Interfaces of Unknown Provenance

The amended standard was released with a red-lined version, which enables the reader to quickly see the changes. Interestingly, a change in Annex C was not marked as such. Annex C covers User Interfaces of Unknown Provenance (UOUP). This section references parts of Section 5 that are still applicable to UOUP and in contrary to IEC 62366-1:2015, the 2020 amendment references sections 5.1–5.9 while IEC 62366-1:2015 references 5.1–5.8.

The reason this is interesting is that it seems like a simple typo, but upon further inspection, it turns out to be a loophole closure. Section 5.9, which Annex C in IEC 62366-1:2015 did not include in its reference, is a clause about performing a Summative Evaluation. Therefore, manufacturers trying to get a UOUP approved and referring to IEC 62366-1:2015 may not have thought a summative evaluation (or justification for a lack of a summative evaluation) was necessary. Now, the standard clearly states that a summative evaluation is needed in order to get a UOUP approved.


In summary, it can be confirmed that no fundamental changes to the usability engineering process as defined in IEC 62366-1:2015 have been made. However, it is clear that readers have to pay close attention to the amended version in order to identify unmarked changes such as the ones to the UOUP process. It will also be interesting to see how regulatory bodies such as FDA will interpret the updated instructions for the selection of hazard-related use scenarios for summative evaluations.

This article was written by Sarah Daniels, Human Factors Engineer for Farm, a Flex company, Hollis, NH. For more information, visit here .