Usability Engineering Process


Before we begin, we need to clarify the definition of usabilty, and we are not talking about its dictionary definition.

The standard IEC 62366-1: 2015 defines usability engineering as below.

Article 3.17
Definition: application of knowledge about human behaviour, abilities, limitations, and other characteristics to the design of medical devices (including software), systems and tasks to achieve adequate usabilitiy.

Article 3.16
characteristic of the user interface that facilitates use and thereby establishes effectiveness, efficiency and user satisfaction in the intended use environment.

So, usability engineering process is a process of establishing effectiveness, efficiency and user satisfaction by applying knowledge about human behaviour, abilities, limitations, and other characteristics to the design of medical devices (including software), systems and tasks.

Application to manual medical devices

The IEC 62366 standards was establihsed only in 2007.
Medical devices have been used by us for thousands and thousands of years.
So, basically, the standard is asking us to prove that the medical devices that we manufacture have adequate usability. Eventhough, some of them are in very much the same shape and design as they were hundreds of years ago.
In case of electrical and electronic medical devices, manufacturers had to comply with the usability requirements set out in IEC 60601-1-6 since 2004. So, it seems these manufacturer are aware of and ready for usability engineering process.
In case of manual medical devices, manufacturers, especially manufacturers of medical devices with long history, such as syringe and needle, surgical knife, sutures, etc., are in chaos.

When IEC 62366 was first establihsed, its scope had intent to covered not just electronic medical devices but also manual medical devices by not indicating specifically that the standard shall be applied to manual medical devices but just saying “it’s applicable to usabilty engineering of medial devices.”

However, maybe because it was issued by IEC (International Electronical committee), its application to manual medical devices felt almost not mandatory before artilce 7.3.3 of ISO 13485: 2016 required to consider usability as an input to design and development process.

User-interface Of Unknow Provenance (UOUP)

One of the special features of IEC 62366-1: 2015 is that it distinguishes medical devices designed before and after Oct. 2007. Medical devices designed before Oct. 2007 must now follow usability engineering process of User-interface Of Unknown Provenance (UOUP), which its specific process are described in Annex C.

Medical device deisnged after Oct. 2007, shall go through whole usability engineering process described in the articl 5 of the standard.

One thing you want to keep in mind is that the test plan and report for usability does not constitute a full set of usability engineering file. There are considerable numbers of medial device that might not need such test.

The structure and contents of Usability Engineering File is as below.

5.1 Use specificaiton
Intended user, intended use, use environment, requirements, etc.
5.2 User interface characteristics related to safety and potential use errors
The manufacturer shall identify user interface characteristics that could be related to safety as part of a risk analysis performed according to ISO 14971:2007, 4.2.
5.3 Identify known or foreseeable hazards and hazardous situations
The manufacturer shall identify known or foreseeable hazards and hazardous situations, which could affect patients, users or others, related to use of the medical device. This identification shall be conducted as part of a risk analysis performed according to ISO 14971:2007, 4.3 and the first paragraph of ISO 14971:2007, 4.4.
5.4 Identify and describe hazard-related use scenarios
The manufacturer shall identify and describe the reasonably foreseeable hazard-related use scenarios associated with the identified hazards and hazardous situations.
5.5 총Select the hazard-related use scenarios for summative evaluation
The manufacturer shall select the hazard-related use scenarios to be included in the summative evaluation.
5.6 Establish user interface specification
The manufacturer shall establish and maintain a user interface specification.
5.7 Establish user interface evaluation plan
The manufactuerR shall establish and maintain a user interface evaluation plan for the user interface specification.
Formative evaluation
Summative evaluaiton
Usabiltiy test (Decision of whether or not to implement usability test shall be based on the risk and complexity associated to the user interface of the device.)
5.8 Perform user interface design, implementation and formative evaluation
The manufacturer shall design and implement the user interface, including the accompanying documentation if needed, and training capability, if needed, as described in the user interface specification
5.9 Perform summative evaluation of the usability of the user interface
Upon completion of the design and implementation of the user interface, the manufacturer shall perform a summative evaluation of each hazard-related use scenario selected in 5.5 on the final or production equivalent user interface according to the user interface evaluation plan

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