The first article provides an overview of the guidance document dedicated to the human factors and the way they should be considered when developing user interfaces for medical devices. 



The Food and Drug Administration (FDA or the Agency), the US regulating authority in the sphere of healthcare products, has published a guidance document dedicated to applying human factors and usability engineering to medical devices. The document is intended to provide additional clarifications regarding the applicable regulatory requirements and the way corresponding legislation should be interpreted, as well as recommendations to be considered by medical device manufacturers and other parties involved. At the same time, the authority explicitly mentions that provisions of the guidance are non-binding. Moreover, an alternative approach could be applied, provided such an approach is in line with the existing regulatory framework and has been agreed with the authority in advance. The document is intended to assist industry representatives in achieving and sustaining compliance with the applicable regulatory requirements, and also ensuring the safety and effectiveness of medical devices produced. 


Regulatory Background 

As described by the FDA the guidance recommends that manufacturers follow human factors or usability engineering processes during the development of new medical devices, focusing specifically on the user interface, where the user interface includes all points of interaction between the product and the user(s) including elements such as displays, controls, packaging, product labels, instructions for use, etc. However, the authority is mostly focused on ensuring that any medical devices allowed to be marketed and used in the US meet the applicable requirements in terms of safety, quality, and effectiveness, while any issues that could result in exposing patients to additional risks are duly identified and eliminated at the early development stage. Hence, medical device manufacturers are responsible for conducting a rigorous risk analysis and implementing measures based on its results. In this regard, the authority refers to the applicable standard ANSI/AAMI/ISO 14971, Medical Devices – Application of risk management to medical devices which defines risk as to the combination of the probability of occurrence of harm and the severity of the potential harm. At the same time, the authority acknowledges that in case of use errors it is quite difficult to evaluate properly since certain issues could not even be identified unless the device will be used for its intended purpose. Should upon completion of a risk assessment the manufacturer identify the risks that could potentially result in severe harm caused to patients, the appropriate human factors or usability engineering processes should be applied as described by the FDA. The same approach should be applied in case of additional actions taken by the manufacturers in case the issues were identified after the device became available on the market. 

As further explained by the FDA, human testing stands for evaluating the device from the perspective of use errors which may occur when the device is used in a wrong way (the actions are incorrectly taken by the users, or not taken at all). If due to the nature of the device such use could result in the harm caused to the user or patient, the appropriate information about such an assessment should be included in a premarket submission. Thus, the necessity of submitting the details on human testing depends on the type of medical device in question and its specific features. 


To ensure correct interpretation of clarifications and recommendations contained in the guidance, the Agency also provides definitions of the most important terms and concepts used in the context of the document including, inter alia, the following ones:

Abnormal use – an intentional act or intentional omission of an act that reflects violative or reckless use or sabotage beyond reasonable means of risk mitigation or control through the design of the user interface. 

Critical task – user task which, if performed incorrectly or not performed at all, would or could cause serious harm to the patient or user, where harm is defined to include compromised medical care. 

Human factor engineering – the application of knowledge about human behavior, abilities, limitations, and other characteristics of medical device users to the design of medical devices including mechanical and software-driven user interfaces, systems, tasks, user documentation, and user training to enhance and demonstrate safe and effective use. 

Apart from the ones listed hereinabove, the guidance also provides the definitions of such terms as “Formative evaluation”, “Hazard”, “Hazardous situation”, “Human factors validation testing”, “Task”, “Use error”, “Use safety”, “User”, and “User interface”. The latter stands for all points of interaction between the user and the device and covers all interfaces. 


Main Principles 

According to the guidance, understanding how people interact with technology and studying how user interface design affects the interactions people have with technology is the focus of human factors engineering (HFE) and usability engineering (UE). Concerning the above, a manufacturer should consider the three key components, namely:

  1. Users of a medical device;
  2. The environment in which a device is intended to be used; and
  3. Device User Interface. 

All the above mentioned factors impact significantly whether the device would be used correctly, or user errors would result in additional issues related to the safety and effectiveness of the device. Consequently, it is vitally important for a medical device manufacturer to take all the measures to eliminate the design-related issues or at least to reduce them to the lowest extent possible (to an acceptable level). 

As further explained by the FDA, the hazards associated with the use of a medical device could be divided into the following categories: 

  • Physical hazards (e.g., sharp corners or edges),
  • Mechanical hazards (e.g., kinetic or potential energy from a moving object),
  • Thermal hazards (e.g., high-temperature components),
  • Electrical hazards (e.g., electrical current, electromagnetic interference (EMI)),
  • Chemical hazards (e.g., toxic chemicals),
  • Radiation hazards (e.g., ionizing and non-ionizing), and
  • Biological hazards (e.g., allergens, bio-incompatible agents, and infectious agents).

At the same time, the factors listed hereinabove are related to the device itself, and not to the way it is used. Thus, the authority finds it necessary to distinguish use-related hazards as a separate category. According to the guidance, such hazards appear in situations when the device is used in a wrong way due to the issues related to the user interface design resulting in incorrect interpretation of the information or situation. 

For example, use-related hazards can take place in case: 

  • The abilities needed to operate the device correctly actually exceed the ones a user has;
  • There is no consistency in operations of the device;
  • The environment in which the product is used impacts its operations, but this impact could not be properly identified by a user;
  • The environment impacts the ability of a user to receive and analyze information;
  • The device is used in a wrong way, and such use could be reasonably foreseen by the manufacturer, hence, the appropriate measures should be taken to mitigate the risks associated with such use. 

In summary, the present FDA guidance highlights the key points related to the way the human factors should be considered to ensure the safety and effectiveness of a medical device. The authority outlines the most important aspects and provides recommendations regarding the approach to be applied. 


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