Human Factors Engineering Notes

Introduction to Human Factors Engineering (HFE)

• Human Factors Engineering (HFE), also known as human factors and ergonomics, is a multidisciplinary field focused on understanding interactions between humans and system elements.
• It studies factors influencing human performance: cognitive abilities, physical capabilities, perceptual processes, social dynamics, and environmental conditions.
• HFE applies principles from psychology, engineering, physiology, anthropology, and other disciplines.
• The goal is to design systems that are intuitive, efficient, and safe for human use.
• In the medical device industry, HFE ensures devices are safe, effective, and user-friendly.

Role of Human Factors in Medical Devices

• Human factors are crucial for the safety and efficacy of medical devices.
• Professionals identify potential risks and develop mitigation plans by understanding human-device interface dynamics.
• Intuitive interfaces, ergonomic features, and clear instructions promote correct device use.
• Optimized design enhances user experience, device safety, and effectiveness.
• User-friendly interfaces and streamlined workflows minimize physical and cognitive load.
• Investment in HFE yields cost savings through reduced use errors and decreased training needs.

Usability Engineering (UE) vs. HFE

• Usability Engineering (UE) finds applications across various industries.
• HFE is focused on optimizing human-device interactions during design and development.
• UE applies HFE principles to validate usability.
• HFE begins early, addressing user needs, risks, and ergonomics.
• UE emphasizes testing and validation to meet user requirements and regulatory standards.
• Together, HFE and UE enhance device safety and effectiveness.

Regulatory Requirements for HFE

• Regulatory bodies require HFE to ensure device design prioritizes user safety and effectiveness.
• Studies identify potential use errors and design flaws by understanding user interactions with devices and labeling.
• The goal is to eliminate or reduce use errors that could cause harm or degrade medical treatment.
• Final assessments justify in regulatory submissions that the device can be used safely and effectively.

Device Use-related Safety

• HFE focuses on designing intuitive, user-friendly, and error-resistant UIs.
• Understanding user capabilities in specific use environments helps identify challenges in use/design flaws.
• Designers need to be informed about human factors studies' findings to develop effective mitigation plans.
• Diverse user populations (lay users with limited medical knowledge or compromised capabilities) create design and evaluation challenges, requiring more manufacturer oversight.

Risk Management

• Human factors studies provide data and insights for risk management.
• It helps identify, understand, and mitigate potential use failures and determine risk acceptability.

Regulatory Compliance for Premarket Submission

• Regulatory bodies (FDA, EMA, NBs in the EU) require human factors data/studies for medical device approval.
• Compliance is crucial for obtaining premarket clearance/approval.
• Ensures devices meet regulatory requirements for safety and effectiveness.

Postmarket Surveillance

• Postmarket surveillance identifies use-related risks not recognized in premarket evaluations.
• Regulatory affairs professionals monitor device performance and report adverse events.
• HFE is incorporated to enable strategic decisions regarding response actions for usability issues.

Key Human Factors Activities and Deliverables

Human Factors Activities

• ISO 13485 standard describes design and development phases for medical devices, each involving HFE activities.
• The objective is to oversee safety work and ensure use-related risks are controlled throughout the product lifecycle.
• Required human factors work varies depending on risk levels from use error/failure.
• Risk level factors: type of medical device, scale of UI change, intended user groups, and use environment.
• Manufacturers may have their own specific standards of process.

Table 11-1: Recommended Human Factors Work for Design Control Phases

HFE Deliverables

• UI Requirement Specifications: Defines how product should be designed to meet user needs and UI requirements, including: device features, UI, operational principles, functions, and performance.

  • Specific need statements written by human factors professionals, considering user capability/expectation in designated use environment.
  • Translated into UI design requirements/technical specifications with the engineering team.

• Human Factors Engineering Plan: Documents all human factors activities to be completed for medical device development, including evaluation scope, strategy, and final human factors deliverables.

  • Team members fully understand the medical device design or change scale; discuss with other functions (research/ development/regulatory affairs) to propose relevant human factors work.

• Task Analysis: Documents workflow, user interactions, and potential points of use error/difficulty.

  • Analyzes how each task is accomplished, including a detailed description of break-down activities.
  • Factors: task/ element durations, task frequency, task allocation, task complexity, environmental conditions, necessary clothing/equipment, and other unique factors involved.

• Use-related Risk Analysis (URRA): Built upon task analysis; a risk management tool supporting entire human factors engineering.

  • Lists use-related hazards, potential harms/ severity levels, mitigations, and risks after mitigations.
  • Identifies critical tasks; helps product developers understand risks in use process and tasks with higher risks that require mandatory evaluation/mitigations.
  • Task analysis and URRA can be integrated into one deliverable.
  • URRA is a living document updated throughout the development process based on cross-functional works, including human factors.
  • Upon completion of a human factors validation study, URRA needs to be reviewed and finalized to determine the acceptability of residual risks.

• Critical Task: User task which, if performed incorrectly or not performed at all, would/could cause serious harm to the patient or user (CDRH definition).

  • For combination products, CDER's definition refers to all tasks that may potentially result in any level of harm or injury.
  • Refer to FDA guidance for details.

• Human Factors Formative Study Protocol(s) and Report(s): Deliverables associated with human factors formative studies conducted during device development.

  • Studies the UI or user interactions to identify UI design strengths/weaknesses and potential use errors.
  • Objectives:
    • Exploring and identifying unforeseen use errors and risks, then update the URRA.
    • Informing design team about any improvement/adjustment needed to further mitigate use-related risks.
    • Confirming the success of design outputs (UI's, labeling, training material, etc.) that meets design input requirements.
  • Early performance of formative studies can benefit the entire device lifecycle by identifying and addressing issues early avoiding higher costs for modifications at later stages.

• Human Factors Summative/Validation Study Protocol and Report: Deliverables associated with the human factors summative/validation study.

  • Final evaluation of UI before premarket application submission.
  • Evaluates users’ performance on all critical tasks related to device use and labeling.
  • Referencing task analysis and URRA, this study is conducted with representative participants of the intended user group, typically via simulated use.
  • Task performance data demonstrates all use-related risks have been mitigated and residual risks are acceptable.
  • Ideally, the report concludes that use-related risk management measures are effective and residual risks are acceptable.
  • A key part of design validation.
  • In situations where simulated-use testing is not possible or necessary, clinical testing/engineering bench testing can be used alternatively.

• Human Factors Engineering/Usability Engineering Report: Commonly used final human factors report for the FDA in the US summarizing all human factors activities (user research, formative evaluations, known use problems, etc.).

  • If residual risks are unacceptable, a risk-benefit analysis may be used to demonstrate benefits outweigh risks; otherwise, redesign/further mitigation is needed.

• Usability Engineering File: Collection of documents/records created during the usability engineering process for medical devices; serves as design and development control process.

• Medical device manufacturers have different responsibility allocations in their organization.

• Deliverables might not be named the same way across different organizations. Marketing might oversee collecting user needs at the early stage of product development.

• Input from human factors subject matter experts should be sought when preparing the content and documentation.

Scenarios Where Human Factors Work are Required

• Human factors data are required by regulatory bodies if incorrect use results in serious harm.
• Common for regulatory bodies to require HFE and/or usability testing for most lay-person devices, software-controlled devices, or ones that have software interface(s).
• For the European market, there is no change in intended users, use tasks, UI's, or use environment from previous versions/models of devices, applicants can submit an Evaluation of User Interface of Unknown Provenance (UOUP) report instead (IEC 62366-1 Appendix C.11).
• Manufacturers are required to mitigate the use-related risks of new medical devices, where there is no other similar device(s) on the market.
• For existing medical devices, where there are design changes (UI, intended users, use environment, use tasks, training, and labeling, etc.), human factors evaluations and data may be required to investigate and assess their impact and the use-related risk profile.

Requirement of Human Factors in Different Geographic Areas

• Regulatory requirements vary across regions but emphasize ensuring devices are safe and effective.
• Primary regions: North America, Europe, and Asia.
• Requirements aim to minimize usage errors, enhance usability, and improve patient safety.
• Compliance is vital for regulatory approval or clearance to market devices.

Human Factors Requirements in North America

• US (FDA): Requires HFE integration into design and development processes.
  • FDA guidance document: Applying Human Factors and Usability Engineering to Medical Devices.
  • Usability tests with representative users to identify and rectify use errors and safety hazards.
  • High regulatory system maturity, robust HFE enforcement, thorough review and feedback.
• Canada (Health Canada): Requires manufacturers to address human factors and usability engineering
  • Guidance on Clinical Evidence Requirements for Medical Devices: Clinical Data and Evaluation.
  • Usability testing with representative users to assess safety and effectiveness.
  • Moderate regulatory maturity with enforcement, review and feedback levels.

Human Factors Requirements in Europe

• European Union (EU): Compliance with the Medical Device Regulation (EU MDR) or the In Vitro Diagnostic Medical Device Regulation (EU IVDR) is mandatory for medical device manufacturers, depending on the device type.
  • EU MDR and EU IVDR underscore the importance of human factors in ensuring device safety and performance (for instance, Annex I of the EU's General Safety Performance Requirements).
  • Manufacturers must consider users, environments, and potential risks.
  • Standards (CENELEC EN 62366-1 originally from IEC) provide guidelines.
  • Moderate regulatory maturity, high HFE review and feedback from NBs, reflecting increased regulatory focus due to heightened HFE requirements under EU MDR compared to the EU's regulatory laws as covered by the Medical Device Directive (MDD).
• United Kingdom (UK): Requires compliance with Guidance on Applying Human Factors and Usability Engineering to Medical Devices Including Drug-Device Combination Products in Great Britain.
  • Regulatory maturity and enforcement by MHRA expected to be similar to the EU.

Human Factors Requirements in Asia

• China and Japan: Regulatory requirements exist but vary depending on regulations and standards.
• Manufacturers marketing devices in multiple regions must ensure compliance with the regulatory requirements of each target market.
• Relatively low regulatory maturity, with minimal HFE enforcement and review and feedback on submissions.
• Increasing expectation to include local HFE data in submissions or provide justification from the National Medical Product Administration (NMPA) in China.

International and National Organizations for Human Factors

• International Organizations:
  • ISO, IEC, and WHO.
  • IEC and WHO also consider HFE.
• In the US:
  • FDA's CDRH: responsible for assuring that patients and providers have timely and continued access to safe, effective, and high-quality medical devices and safe radiation-emitting products. CDRH reviews human factors engineering data as part of its evaluation of the safety and effectiveness of medical devices.
  • FDA's CDER: responsible for regulating the safety and efficacy of prescription and over-the-counter drugs. It reviews human factors work for drug products, including the evaluation on factors such as medication labeling, packaging, and administration devices.
  • Advancement of Medical Instrumentation (AAMI): serves as one of the primary sources of consensus standards for the medical device industry. It provides training courses on human factors for medical devices every year and joins the standards consensus work in harmonization with other international standards committees for human factors.
• In the EU:
  • The European Medicines Agency (EMA) plays a key role in regulating medicines for human use in the European Union (EU), with a focus on the centralized procedure.
  • A NB is an organization designated by an EU Member State that is responsible to provide the conformity assessment of medical devices before they are placed on the market or put into service.
• Health Canada, MHRA in the UK, and NMPA in China have specific requirements for human factors work in medical devices, which can be found on their official websites.
• The aforementioned organizations do not constitute an exhaustive list; they are the most common organizations or regulatory bodies that have HFE considerations as part of their regulatory requirements.

Human Factors-related Standards and Guidance

• Varying requirements across regions.
• Table 11-2 outlines general requirements for specific types of medical devices.
• Regulatory bodies, international standards committees and working groups also published many other standards that serve as guidelines for specific areas in human factors work for medical device development (e.g., labeling, instructions for use development, etc.).

Table 11-2: Human Factors Related Standards and Guidance

Conclusion

• HFE and usability are essential to medical device regulatory requirements.
• The work envisions integrating safety, effectiveness, usability, and innovation, addressing user needs and enhancing healthcare outcomes through medical devices.
• Embedding HFE principles throughout a device's lifecycle minimizes risks, improves user experience, and supports healthcare demands.
• Global standards and regulations emphasize HFE’s importance as its integration ensures device safety and effectiveness.
• Beyond compliance, HFE fosters innovation and better healthcare delivery, making it a cornerstone of medical device development.