IEC 60601-1 3rd edition requires that manufacturers must address the risk of poor usability, including those associated with identification, marking and documents. This is accomplished by performing a usability engineering process that complies with IEC 62366 ‘Application of usability engineering to medical devices’.

Safety and competitiveness through increased usability

A report in 1999 by the Institute of Medicine titled, ‘To Err is Human: Building A Safer Health System’ stated that at least 44,000 people, and perhaps as many as 98,000 people, die in US hospitals each year as a result of medical errors that could have been prevented. The report concluded that the majority of medical errors were not a result of individual recklessness, instead the report warned that errors were due to faulty systems, processes and conditions that lead people to make mistakes or fail to prevent them.

Today, both the MDD and FDA require that human factors and risk of use errors be accounted for in the development of medical devices. International standards, such as IEC 60601-1 Ed3 and specifically IEC 60601-1-6, address usability engineering and aim to minimize risks caused by poor usability. In any situation where medical devices are used there is a responsibility to ensure only well-designed, ergonomic products make it to market. The easier a product is for the user, the safer it is for the patient, and consequently the product can increase its competitiveness in the market place.

IEC 62366 guidance and implementation

IEC 62366 provides extensive guidance on how to implement usability engineering to minimize risks. The standard, a 100-page document, defines the user interface design cycle in medical context as shown below:

                               Usability engineering as a cycle of steps

To more clearly understand how the steps of the design cycle relate to IEC 62366, the following table illustrates the usability engineering process:

Design cycle elementSubclause of IEC 62366Methods
User research / Conceptual design

5.1        Application specification

5.2        Frequently used functions

5.3        Identification of characteristics related  to Safety

    5.3.1    Identification of known or foreseeable Hazards and Hazardous Situations

User logbooks
Workflow analysis
Use cases
Requirement and criteria development

5.4         Primary Operating Functions

5.5         Usability Specification

5.6         Usability Validation Plan

Functional requirements

Usability requirements:

  • Efficiency
  • Freedom from errors
  • Time to learn
Detailed design and specifications 5.7         User Interface Design and Implementation

Design procedures
Style guides


5.8        Usability Verification

5.9        Usability Validation

    5.3.1     Identification of known or foreseeable Hazards and Hazardous Situations

Expert analysis
Heuristic evaluation
Cognitive evaluation
User tests: pair and group tests

 Bringing all products up-to-date

The design of many products that are already in use did not explicitly require usability engineering in their design. To address this problem, proposal 62A/799/DC exists to initiate a fast-track amendment to the IEC 62366 standard. The proposed amendment defines User Interface Of Unknown Provenance (UOUP). To evaluate UOUPs, a new Annex K is to enforce the usability engineering process to legacy devices, minor changes to legacy devices or to off-the-shelf components incorporated in medical devices.

Conclusion – ‘How to design good usability?’

It is not possible to add good usability into a product as an afterthought. To meet the requirements of IEC 62366, usability engineering has to be incorporated into planning from day zero and the process needs to be recorded all the time. Regulations have made usability engineering a must, but at the same time good usability is a great distinguisher and part of a competitive advantage.

“There is a learning curve and there is a bad design. In many cases they are the same thing.”

It is invaluable to ask and observe the actual users with regards to how they use competing equipment or rough early prototypes. If a user doesn’t need to ask instructions, or develop workarounds to accomplish what he/she intends to do, you are on the right track with your product. If you have, at the same time, crafted an aesthetically pleasant piece of equipment or software, you are about to create a winner!