IEC 62366-1:2015

Usability Engineering and Its Impact on IFU Translation

IEC 62366-1:2015 and the Translation of Instructions for Use

IEC 62366-1:2015 establishes a systematic process by which manufacturers are to ensure the usability of their medical devices. What many manufacturers overlook: the standard considers the Instructions for Use as an integral part of the user interface. This means usability requirements apply not only to the physical product but explicitly also to the accompanying documentation – in every language version.

Instructions for Use as a User Interface

IEC 62366-1 defines the user interface as "all means by which a user and a medical device interact with each other". This explicitly includes the accompanying documentation. The Instructions for Use are therefore not a secondary supplementary document but a safety-critical element of the user interface. Errors in translation can directly lead to use errors and thus to hazards.

Usability Engineering Process and Translation

The usability engineering process described in the standard comprises several phases relevant to translation:

1. **Use specification**: Identification of the intended users, their capabilities and limitations. For translation, it is particularly relevant whether the users are healthcare professionals or lay persons, as this determines the linguistic complexity of the translation.

2. **Analysis of use-related hazards**: Identification of use scenarios in which incorrect or incomprehensible information could lead to hazards. Translation errors fall directly into this category.

3. **User interface specification**: Determination of how information should be presented. This includes decisions on symbols, font sizes, warning formats, and structuring, all of which have implications for translation.

4. **Summative evaluation**: The final demonstration that the user interface can be used safely. The question of whether translated versions must also undergo summative evaluation is debated in the industry. However, there is consensus that at least a professional review by native-speaking experts should be conducted.

Symbols as a Cross-Language Communication Tool

The use of harmonised symbols per ISO 15223-1 and IEC 60417 can reduce language barriers. However, IEC 62366-1 emphasises that the comprehensibility of symbols must be empirically demonstrated. This also applies to symbols that are widely recognised in one cultural context – they may be interpreted differently in other regions. Manufacturers should be aware that cultural differences in symbol interpretation can exist even for ISO-standardised symbols.

Layout Requirements and Text Expansion

A frequently underestimated problem with multilingual Instructions for Use is text expansion: texts in different languages require different amounts of space. Finnish text, for example, is on average 30–40% longer than English text, while Chinese text is often shorter. IEC 62366-1 requires legible and clear presentation – a requirement that can only be met if the layout is designed for internationalisation from the outset.

ManualWorks supports manufacturers in creating internationalisation-ready layouts and provides preview functions for all target languages, so that layout issues can be identified and resolved early.

Conclusion

IEC 62366-1:2015 makes clear that the translation of Instructions for Use is not an isolated process but an integral part of the usability of a medical device. Manufacturers must ensure that their translation processes guarantee the comprehensibility, legibility, and safety of the Instructions for Use in every target language.

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