Human factors principles have long been applied in high-hazard industries such as aerospace, nuclear, petrochemical, energy and transport in an effort to minimize potential risks. Increasingly, human factors in the life science industry have become recognized as an important topic. While human factors engineering was previously only accepted as necessary for electro-medical devices with complex user interfaces, it has evolved to become a mandatory design input requirement for the development of the majority of medical products throughout the globe.
Human Factors: Why does it Matter for Patient Safety?
A large number of medical devices are used for critical patient monitoring and errors in use, leading to patient harm, have progressively become a main cause for concern for manufacturers and patients alike. The cause of such errors can often be due to poorly designed device user interfaces, particularly where a complex user system is involved.
Infusion pumps, ventilators, automatic electronic defibrillators and drug-device combination products (e.g. auto-injectors) are recognized as potentially having user interface-related issues that can result in severe hazards such as overdoses and dangerous delays or difficulties in delivering medication.
Medical devices have become more and more diverse in their capabilities and are used with increased frequency in busy environments with new distractions and requirements for specialized training. As patient care evolves and is transferred to private homes or public environments, less skilled or even unskilled users including patients and caretakers must be enabled to safely use of these complex devices.
|Human Factors Considerations||Users||Use Environment||Device-User Experience|
Figure 1: Human Factors Affect Outcomes of Using Medical Devices (Obtained from: FDA’s Applying Human Factors and Usability Engineering to Medical Devices, FDA 2016)
Usability Engineering within Regulatory Frameworks
The U.S. Food & Drug Administration (FDA) receives about 100,000 medical device incident reports every year. More than one third of these reports are assumed to be attributed primarily to user error. This number correlates with published FDA trending data analysis on Medical Device Recalls between FY2003 to FY2012 .
Figure 2: U.S. FDA Recalls, by Category (FY2003 – FY2012)
The cited report concludes that while design-related failures have been the leading cause of medical device recalls, a review of trends over the last three (3) years shows that the percentage of device design recalls has remained stable.
Evaluating the Most Common Cause of Recall – Software Design Failures
Medical device software may be in the device itself or may be used to manufacture a medical device. Medical products increasingly rely on software and seemingly, minor changes to software can have important implications for device functionality and clinical performance. Failure to implement software design controls testing procedures for increased environmental user complexities, where appropriate (with increased connectivity and interoperability) can lead to software anomalies often requiring a correction or removal.
As a consequence of these trends, the FDA released several new guidance documents to emphasize the need for human factors engineering in design and development of medical devices and systems, including:
|Applying Human Factors and Usability Engineering to Medical Devices||February 2016|
|List of Highest Priorities Devices for Human Factor Review (draft guidance)||February 2016|
|Guidance for the Content of Pre-Mmarket Submissions for Software Contained in Medical Devices||May 2005
The incoming international Quality Management System Standard “ISO 13485:2016, Medical devices – Quality management systems – Requirements for regulatory purposes,” was recently revised, and among other new requirements, emphasizes the need for usability engineering as a mandatory design input. Other related sections refer to the output of usability requirements such as required user training to ensure specified performance and safe use of the medical device in its intended environment.
Human factors design and usability engineering requirements for medical device design and development are explicitly implemented into current and forthcoming EU regulatory directive frameworks as well.
In 2010, Directive 2007/47/EC  amended the Medical Device Directive (MDD) and Recital 18 provided the background to the introduction of more specific human factors (i.e. ergonomics requirements into the MDD):
“As design for patient safety initiatives play an increasing role in public health policy, it is necessary to expressly set out the need to consider ergonomic design in the essential requirements. In addition, the level of training and knowledge of the user, such as in the case of a lay user, should be further emphasized within the essential requirements.
The manufacturer should place particular emphasis on the consequences of potential misuse of the product and its adverse effects on the human body.”
(Note: the term ‘misuse’ in the directive is best interpreted as ‘user error’ in this document, as distinct difference from ‘abnormal use’ as defined above.)
The essential requirements (ER) in Annex I of the MDD  include specific requirements for human factors, which are highlighted below. These essential requirements are also relevant to device components of drug-device combination products that are regulated as medicines (see MDD: M5 Article 1.3):
ER 1: The devices must be designed and manufactured in such a way that, when used under the conditions and for the purposes intended, they will not compromise the clinical condition or the safety of patients, or the safety and health of users or, where applicable, other persons provided that any risks which may be associated with their intended use constitute acceptable risks when weighed against the benefits to the patient and are compatible with a high level of protection of health and safety.
This shall include:
1) reducing, as far as possible, the risk of user error due to the ergonomic features of the device and the environment in which the device is intended to be used (design for patient safety); and
2) consideration of the technical knowledge, experience, education and training and where applicable, the medical and physical conditions of intended users (design for lay, professional, disabled or other users).
- ER 9.2: the risk of injury, in connection with their physical features, including the volume/pressure ratio, dimensional and where appropriate ergonomic features;
- ER 10.2: the measurement, monitoring and display scale must be designed in line with ergonomic principles, taking account of the intended purpose of the device;
- ER 13.1: Each device must be accompanied by the information needed to use it safely and properly, taking account of the training and knowledge of the potential users, and to identify the manufacturer; and
- Other ERs that may be indirectly affected by human factors design include 2, 3, 6, 12.8. and 12.9.
The new EU-Medical Device Regulations MDR/2017/745  further mandate the need for human factors/usability engineering. Annex 1, General Requirements for safety and performance requirements, states in section 5:
In eliminating or reducing risks related to use error, the manufacturer shall:
- reduce as far as possible the risks related to the ergonomic features of the device and the environment in which the device is intended to be used (design for patient safety), and
- give consideration to the technical knowledge, experience, education, training and use environment, where applicable, and the medical and physical conditions of intended users (design for lay, professional, disabled or other users).
MDR Article 1(12)
Devices that are considered to be machinery within the meaning of point (a) of the second paragraph of Article 2 of Directive 2006/42/EC  shall, where a hazard relevant under that Directive exists, also meet the essential health and safety requirements set out in Annex I. This is to be done to the extent to which those requirements are more specific than the general safety and performance requirements set out in Chapter II of Annex I to this Regulation.
2006/42/EC (Machinery Directive) Annex 1 
Under the intended conditions of use, the discomfort, fatigue and physical and psychological stress faced by the operator must be reduced to the minimum possible, taking into account ergonomic principles such as:
- allowing for the variability of the operator’s physical dimensions, strength and stamina,
- providing enough space for movements of the parts of the operator’s body,
- avoiding a machine-determined work rate,
- avoiding monitoring that requires lengthy concentration, and
- adapting the man/machinery interface to the foreseeable characteristics of the operators.
Product Life Cycle and Continuous Improvement
To meet current and future stringent regulatory requirements, usability engineering must be planned, implemented and verified into the product design and development from the concept phase to the final validation of the device and even within the post-market phase. (Post-market surveillance (PMS) is defined as part of continual benefit-risk profiling of all medical devices/IVDs and combinations of medical devices used with medicines.)
Considering the wide range of medical devices and drug-device combination products, a flexible approach to regulatory requirements is necessary, depending on the type of device, intended use and known user errors of similar devices. However, the approach taken should be risk-based, justified and appropriately documented throughout the product life cycle.
The MDR outlines the concept of continual improvement in Article 83 post-market surveillance system of the manufacturer. Section 3 f) requires explicitly that PMS data should be used “for the identification of options to improve the usability, performance and safety of the device.”
The best industry practice is to continually improve the user interface throughout the life cycle of a product. A robust change management process is required throughout the product life cycle to efficiently address user interface changes, whether derived from pivotal trial data, feedback from post-market surveillance, or information obtained as a result of component supply issues.
Figure 3 below represents the principle concept of product usability life cycle development:
Figure 3: Human Factors as Part of Benefit-Risk Management Throughout the Product Life Cycle (Adapted from MHRA’s Human Factors and Usability Engineering: Guidance for Medical Devices Including Drug-Device Combination Products, Sept. 2017)
Optimal clinical outcomes are often delivered through summative testing/design validation, risk management and post-market vigilance. This includes human factors considerations such as post-market surveillance of own and similar devices, device/user interface, customer insights, ethnographic research, healthcare provider training, and incident analysis and reporting. Device manufacturers can also benefit from conducting MD/IVD benefit-risk profiling that includes identification of use, user environment(s), risk assessment of use and user error, prioritization of tasks and user interface related to safety, and conducting formative testing and design iteration.
Conclusion: What does this all Mean?
Regulatory requirements for safe and effective medical devices are ever-changing, however the majority of new and emerging frameworks mandate stronger and deeper considerations of human factors/usability engineering to ensure patient safety and clinical performance prior to market access and beyond.
Increasingly, it will be of more importance to carefully discuss and evaluate usability design input factors of potential user groups and a device’s intended use throughout all product development stages (pre-clinical testing, clinical investigation, market access and post-production) with documented justification of the approach taken.
Poor device usability can no longer be ignored or neglected in developing medical devices for market access and continued commercial acceptance.
How can NAMSA Help?
NAMSA’s quality experts welcome the opportunity to discuss strategic options related to human factors and usability engineering. Contact us at firstname.lastname@example.org, or visit our ISO compliance and quality systems consulting webpage here to learn how we can assist your medical device organization in achieving end-user safety.
References and Additional Resources:
 Applying Human Factors and Usability Engineering to Medical Devices Guidance for Industry and Food & Drug Administration Staff (February 3, 2016)