IEC 62366-1:2015 new information on the usability standard

The standard on the usability engineering process, IEC 62366-1:2015, has been amended several times since it was published in 2015. Corrections were made in 2016 in the form of the corrigendum. With 2020 amendment (AMD1:2020) resulted in significant changes that manufacturers of medical devices now need to familiarize themselves with.

The following article

• lists all of the important changes to IEC 62366-1:2015 and explains them,
• provides information about the status of harmonization.

1. Background and objective of IEC 62366-1:2015

The usability engineering process described by IEC 62366-1:2015 aims to ensure that risks that may arise when using medical devices are minimized. The target audience for the standard is manufacturers of medical devices and also technical committees that are responsible for the creation of specific standards for medical devices.

IEC 62366-1:2015 is the successor to 62366:2007. To clean up the normative part, the new version of IEC 62366 is made up of two parts:

• the standard itself (IEC 62366-1) and
• the informative technical report (IEC 62366-2).

2. The significant changes introduced by AMD1:2020

Since IEC 62366-1:2015 was published, experts have identified a total of 22 problems. These have now been remedied by the corrections.

In summary, the significant changes are as follows:

• Editorial changes
  Many of the changes to IEC 62366-1:2015 are merely editorial in nature; e.g. references and years have been updated and passages of text have been reformulated.
• Scope of application
  The scope of application of the standard has changed. It now no longer comprises merely physical hazards, but also dangers of any type (including psychological hazards).
• Definitions 
  The definitions of “accompanying documentation” and “use environment” have been expanded and the definition of the term “user profile” has been changed.
• New terms
  There have been changes to the wording of the standard, including the introduction of new terms. Among other things, the terms “user group” and “critical task” have been introduced, and “close call” is now mentioned.
• New requirements
  There are new requirements for the planning of usability tests within the scope of the summative evaluation and the recording of use difficulties. In addition to the use errors, these must now be recorded in the summative evaluation.
• Risk management and documentation obligation 
  Risk control now also includes training sessions and the documentation obligation for amendments to the usability engineering effort has been lifted.

 Links to the standard texts

• IEC 62366-1:2015 is now available as what is known as a consolidated “redline version”(IEC 62366-1:2015+AMD1:2020 CSV) into which the amendment has been integrated and the changes marked.
• Furthermore, a national version has now also been published (DIN EN 62366-1:2021-08; VDE 0750-241-1:2021-08).
• Amendment AMD1:2020 itself is also available as a single document.

An overview of the topic of the usability of medical devices can be found in our overview article Usability & IEC 62366.

3. The changes in detail

a) Clause 1: All types of hazards are included

• According to note 1 in the first clause, hazards in general are no longer limited to physical hazards. “Direct physical hazards” has been removed from the current version of the standard, so hazards of all types are now included.
• This is also highlighted by the change in Table B.1 in Annex B, which shows examples of possible hazardous situations. Here, the word “physical” in connection with hazards has been removed, too, so now theoretically subsequent psychological harm can also be included that occurs as a result of use errors.

b) Clause 3: New terms and definitions 

Clause 3 of IEC 62366-1:2015 sets out terms and definitions. Here, too, there have been some updates.

Expansion of the definition of accompanying documentation

The definition of “supporting documentation” from Clause 3.2 has been expanded such that it now covers materials containing information about the decommissioning and disposal in addition to those relating to the installation, use, and maintenance of a medical device. 

Change to the definition of use environment conditions

• In Clause 3.20, the use environment continues to be defined as “actual conditions and setting in which users interact with the medical device”. 
• The definition of the “conditions” that make up the use environment, though, has changed. Note 1 to entry clearly states that social features of the use environment such as team work vs. individual use, chaos vs. calm and the stress level play a role in this.

Focus on the individual properties of the user

• The definition of the user profile from 3.29 has changed. The second half of the sentence relating to the user no longer links the characteristics of the user to the requirements of the job or the working conditions, but rather to attributes such as knowledge, skills, and abilities that may have an impact on design decisions (relating to the user interface (UI)).
  The properties therefore now specifically relate to the individual user.

“knowledge, skills, and abilities, which can have a bearing on design decisions”

• The rationales on Clause 3 from Annex A that are not normative but merely informative in nature are also worth noting. Here, the changes relate to the definition of the primary operating function (3.11) and the use scenario (3.22).

Primary operating functions do not need to be determined

In the rationale of the primary operating functions in Annex A, it is predominantly the handling of the primary operating functions that has changed. The rationale of Clause 3.11 now clearly states that these do not have to be determined according to IEC 62366-1:2015. Instead, hazard-based use scenarios shall be identified, described, and evaluated. 
There are, however, exceptions to this:

• In deviation from this, the primary operating functions must be taken into account if they are listed in other product-specific standards and are therefore relevant to the usability engineering process.
• The determination of the primary operating functions is therefore not necessary according to IEC 62366-1:2015, but may under certain circumstances be required in connection with other standards.

Introduction of the term “critical task”

In the rationale of the use scenario (3.22) in Annex A, the term “critical task” was also introduced. 

This describes a task in a hazard-related use scenario in which a use error could lead to significant damage when the task is completed.

c) Clause 4: New information relating to the general principles 

Training of users as a risk control measure

In Clause 4.1.2, which relates to risk management in connection with the design of the user interface, in addition to the existing risk management options [a) “safe design and production”, b) “protective measures”] the option “training of users” has been added in c) in addition to “information on safety”. 

Point c) now says: 

“Information for safety and, where appropriate, training of users“.

Change in usability engineering effort no longer in the UE file

According to Clause 4.3, changes to the usability engineering effort no longer need to be documented in the user engineering (UE) file. This is not an essential requirement in the sense of the standard.

d) Clause 5: Changes to the usability engineering process 

There have also been some changes in Clause 5 on the usability engineering process.

Introduction of the term “user group”

When creating a plan for the user interface evaluation (5.7.1 General), the terminology has changed. If usability tests are part of the plan (formative and summative evaluation), it is necessary to document which user groups are included in the test.

• This Clause used to state “user” and “user profile”. These have now been exchanged by “user group”, which must be documented accordingly. This is rather more of a formal change that will be reflected accordingly when the UE file is created.
• There has also been a corresponding change in Clause 5.7.3 e), which addresses in greater detail what needs to be taken into account when planning usability tests as part of the summative evaluation in terms of user groups.

New requirements for summative usability tests, including recording use difficulties

Clause 5.7.3 relates to the planning of the summative evaluation. The requirements for implementing summative usability tests have changed. The requirement is now for

• the representative nature of the test participants to be ensured,
• there to be an rationale of why the user groups have been selected in this way,
• the correct use to be defined, and
• not just use errors to be recorded, but also use difficulties. 

Use difficulties and close calls

The rationale of 5.7.3 in Annex A addresses the term “use difficulty” in greater detail. 

• Use error
  According to this, a use difficulty occurs typically only temporarily during the use of the medical device and is overcome by the user. If the use difficulty continues, this can become a use error or failure if the user is not able to complete the task as a result. Searching for a function (as a use difficulty) could represent a use error (failure) in the case of time-critical tasks.
• Close call
  A use difficulty where a user almost commits a use error while performing a task, but is able to prevent this is sometimes called a “Close Call”.
  The formulation therefore suggests that Close Calls can also be caused by use difficulties.

Recording of use difficulties in the summative evaluation

Use difficulties are also more important when carrying out the summative evaluation (5.9). The results of the summative evaluation not only need to be analyzed in terms of use errors, but it is also necessary to analyze whether there were any use difficulties. This was not as explicitly mentioned in the previous version of the standard.

Note 1 on this is also important on this, the wording of which is identical to the close call already mentioned from Annex A:

“A use difficulty where a user almost commits a use error while performing a task, but recovers in time to avoid making the use error is sometimes called a ‘close call’.“ 

Source: IEC 62366-1:2015+AMD1:2020

e) Changes in the explanatory graphics in Annex A

Rationale of the connection between IEC 62366-1 and ISO 14971 for the types of use

A new graphic A.4 was introduced in the informative (informative) Annex A, which explains the relationship between the “type of use” in IEC 62366-1 and the concept of “reasonably foreseeable misuse” in ISO 14971. To some extent this is an expansion of the graphic in the Clause “Terms 3.1 – abnormal use”.

The graphic introduces two updates:

1. Firstly, a distinction is made between reasonably foreseeable and not reasonably foreseeable use. The former means the normal (intended) use and the abnormal use. Correct use, in other words error-free, and the "incorrect use" (use error) are still classified as normal use.
2. What really is new is that use errors in normal/intended use and the so-called “abnormal use” are now attributed to “reasonably foreseeable misuse” (from ISO 14971). 

What does that mean for users of this standard?

This is a little unclear. Where is the difference to be set between abnormal use and use with errors? Does the user/manufacturer now need to predict potential abnormal use and check for in usability tests. Certainly not. The fact that abnormal use should now be reasonably foreseeable in addition to possible use errors (or maybe not foreseeable) results in a lack of clarity.

Relationship between risk management and usability engineering strengthened

Graphic A.5 has also been changed, albeit only minimally. It clarifies the processes and links between risk management and usability engineering steps. There is a new focus on mutual exchange. When identifying hazards, scenarios, and user interface (UI) features relevant to safety, it is sensible to collaborate.

• Exchange between risk management and usability engineering
  It has been recognized that there must be increased mutual exchange of information between risk management and usability engineering and not merely one-sided communication to risk management. Arrows towards the usability process have therefore been added. This relates to the activities such as “identify safety-related (UI) characteristics and features” and the determination of known and foreseeable hazards and hazardous situations.
• Risk management and summative evaluation
  A new link between assessment of the risk of hazards in risk management as an input for the determination and description of hazard-related scenarios for the summative evaluation has also been added on the usability side. The reason for this is that the assessment of risks by risk management can be important particularly when selecting scenarios (keyword: criticality).

Changes to hazard-based use scenarios, risk control measures and user interface evaluation

Also in connection with Graphic A.5, we emphasize that the hazard-related use scenarios, risk management measures and the user interface evaluation should be adapted and improved on a continuous (iterative) basis using the results of the formative evaluation.

4. Current information on endeavors to harmonize the IEC 62366-1:2015

The most important  things first:

Unfortunately, harmonization has come to a halt since quite some time. This applies both to this standard and to other standards that were already harmonized with the MDD and need to be harmonized again.

EN ISO 14971 should be harmonized first to pave the way for other standards on the harmonization list. The current IEC 62366-1 is closely linked to this standard. Efforts are underway for other standards such as IEC 60601. As yet, however, all harmonization efforts have failed due to continuous content-related differences with the European Commission in terms of compatibility with the requirements of the MDR – despite all of the efforts to generate formulations compatible with the MDR in additional annexes.

Unfortunately, the way forward remains unclear, although a start has been made with other standards (as of September 2021). However, the validity and applicability of IEC 62366-1 is not affected by the harmonization process.

More information is available in the updated article Harmonized standards: evidence for medical device manufacturers and in the Regulatory Radar.

5. Conclusion

Amendment AMD1:2020 in particular introduced numerous changes into IEC 62366-1:2015 that must be taken into account in the usability engineering process. Most of these changes provide helpful clarifications and improvements. Some, such as the changes to Graphic A.4 in Annex A, raise more questions than they answer. The process of harmonizing the usability standard, which is urgently needed, continues to be delayed.