In the medical device sector, usability is not a mere “optional” aimed at enhancing user experience—it is a critical requirement directly linked to patient safety.
Even the most technologically advanced device can pose significant risks if its use is not intuitive, clear, and free from ambiguity.
User error is among the leading causes of adverse events, treatment delays, and irreversible harm to both patients and healthcare professionals.
A poorly designed user interface or a procedure requiring overly complex steps can turn a life-saving innovation into a potential hazard.
To address this issue systematically, the international standard IEC 62366-1 serves as the primary reference for applying usability engineering to medical devices.
Its goal is to implement a structured and documented process to identify and mitigate risks arising from inadequate usability.
Compliance with this standard is a key step in meeting regulatory requirements, such as those outlined in the European Medical Device Regulation (MDR).
Usability and patient safety: an inseparable link
In this context, usability goes beyond user satisfaction.
It focuses on the interaction between the operator and the device to prevent errors that could lead to harm.
Poor design can result in various risk scenarios, such as:
- Operational errors: A complex interface demands excessive cognitive effort, increasing the likelihood of mistakes—especially in emergency situations
- Failure to activate safety functions: a hard-to-locate alarm button may delay a critical response
- Foreseeable misuse: usability engineering considers not only correct use but also reasonably foreseeable misuse.
For example, a clinician might attempt to clean a sensor improperly, causing a malfunction that should be anticipated and prevented by design
In all these cases, human error is not the root cause of harm—it is the consequence of a design that fails to account for the user’s real capabilities and limitations.
The systematic approach of IEC 62366-1 was developed to overcome these shortcomings by integrating the user’s perspective from the earliest stages of development.
IEC 62366-1: a systematic framework
The standard IEC 62366-1:2015 – Application of Usability Engineering to Medical Devices defines a structured and documented Usability Engineering process, without prescribing a specific evaluation method.
This process must be an integral part of the manufacturer’s risk management system, as required by ISO 14971.
Its primary objective is to identify, analyze, assess, and mitigate safety risks resulting from poor usability.
The process is iterative and consists of several phases that guide the manufacturer from planning to final validation.
Unlike a simple end-product test, the standard emphasizes the need to test and refine the user interface throughout the entire product lifecycle.
Key phases include:
- Usability Engineering planning
- Identification of User Interface Characteristics and Hazards
- User Interface Specification
- Formative Evaluation
- Summative Evaluation
- Documentation and reporting
Phases of the Usability Engineering process
Usability Engineering planning: the first step involves drafting a Usability Engineering Plan that defines the scope and activities of the process.
This document must specify user identification, environment, use cases—including critical tasks—and describe the evaluation strategy, methods, and acceptance criteria (e.g., maximum error rate).Hazard identification and analysis: this phase links IEC 62366-1 with risk management under ISO 14971.
The manufacturer must identify hazards and hazardous situations related to usability.User Interface design and development: based on identified requirements and hazards, the user interface is designed following user-centered design principles.
The goal is to translate safety requirements into concrete solutions that minimize the risk of user error.Formative Evaluation Conducted during device development, this iterative phase aims to identify and resolve usability issues early (e.g., through prototype testing).
Formative evaluation is essential for saving time and resources, as it is more cost-effective to address issues during prototyping.Summative Evaluation: this is the final validation of the usability engineering process, confirming the device’s safety.
It is performed on a product version representative of the final one, using users, tasks, and environments that closely reflect real-world conditions.
The goal is to demonstrate that usability-related risks have been reduced to an acceptable level and that the user interface is safe and effective.
The results of this evaluation determine whether the device is ready for market launch.
The entire process must be documented in a Usability File, which forms part of the device’s technical documentation.
The interconnection between IEC 62366-1 and ISO 14971 is fundamental:
Usability engineering identifies and mitigates risks related to the user interface, while general risk analysis evaluates them.
The Usability File provides objective evidence that risk control measures are effective.
Usability evaluation: a flexible approach for every Medical Device
The IEC 62366-1 standard applies to all medical devices, regardless of their complexity.
The process is flexible, but hazards and design solutions vary significantly depending on the product. Let’s look at a few examples.
Case 1: Substance-Based Medical Device For substance-based devices (e.g., gels, sprays), usability concerns the user experience related to administration, dosage, and storage, rather than buttons or software.
Risks may include:
Incorrect dosage due to unclear delivery mechanisms
Contamination caused by poorly designed containers
Misuse resulting from confusing instructions
The usability analysis is planned by considering specific users and their environment.
During development, prototypes of the delivery mechanism and instructions for use are tested to identify usability issues.
A formal test (summative evaluation) is conducted to demonstrate that users can administer the correct dose and follow the procedure without critical errors.
Case 2: Simple Medical Device (e.g., a patch)
Even a “simple” patch requires usability evaluation to prevent risks.
Here, the user interface includes the packaging and the method of removing the protective layer. Potential hazards include, wound contamination if the user touches the sterile area, incorrect application due to poor design, difficulty opening the packaging.
User analysis considers a wide range of individuals and emergency home-use scenarios.
Formative testing focuses on packaging design (e.g., easy-open tabs).
A summative evaluation is conducted to demonstrate that the packaging and design enable sterile and effective application for most users, minimizing contamination risks.
Conclusion
The IEC 62366-1 standard provides a systematic and adaptable framework for every type of medical device.
Its goal is to apply usability engineering to prevent errors that could compromise the safety and effectiveness of the product.
Adopting this approach is a strategic choice for developing safer, more reliable devices that truly meet users’ needs.
