Human Factors Engineering

« Back to Glossary Index

What it is

Human Factors Engineering (HFE)—also called usability engineering—is the disciplined process of designing devices and IVDs around users, use environments, and use scenarios to reduce use error and improve safety and performance. It aligns with IEC 62366-1:2015+A1:2020 and ISO 14971:2019, with legal hooks in MDR Annex I (e.g., Ch. I §5; Ch. II §14) and FDA design validation (21 CFR 820.30; QMSR). Results feed labeling, training, and risk controls.

Usability engineeringReduce use errorSafety & performance

Regulatory framework

  • EU (MDR/IVDR): General Safety and Performance Requirements require design that minimizes use error and supports intended use (MDR Annex I Ch. I §5; Ch. II §14; IVDR Annex I). Usability evidence belongs in technical documentation (Annex II–III) and informs PMS/PMCF.
  • US (FDA): Design validation must ensure devices meet user needs and intended uses (21 CFR 820.30(g), QMSR). FDA’s human factors guidance expects a risk-based HFE/UE process with summative validation for critical tasks.
  • Standards & guidance: IEC 62366-1 (process), IEC/TR 62366-2 (practical guidance), ISO 14971 (risk linkage), and IEC 60601-1-6/IEC 62366-1 for electromechanical usability.

Key elements

  • User groups and use environments defined (primary, lay, professional, home care, lab).
  • Use scenarios and tasks mapped; critical tasks identified from risk analysis.
  • User interface specification (UI spec) covering hardware, software, alarms, labeling, and training.
  • Formative evaluations to explore and refine design; summative validation to confirm safe use.
  • Traceability between hazards, tasks, UI design, risk controls, and evidence.

Process — how it works

  • Plan: Define HFE plan, users, environments, and success criteria; align with risk policy (ISO 14971; IEC 62366-1 §5).
  • Analyze: Identify use errors and critical tasks from hazards and workflows; then draft UI requirements.
  • Design & iterate: Build prototypes; run formative tests; fix usability issues and update risk files.
  • Validate (summative): Test representative users on final or near-final UI; show critical tasks can be done safely and effectively.
  • Document: Compile the Usability Engineering File (UEF) and feed results into labeling, training, and PMS.

Common pitfalls

  • Skipping real users or using non-representative samples in validation.
  • Focusing on aesthetics over risk-based critical tasks.
  • Testing too late, so key issues require costly redesign.
  • Poor traceability from hazards to tasks to design controls.
  • Assuming training can replace safe UI design.

Quick checks

  • Are critical tasks defined and tested with representative users and environments?
  • Do UI changes trigger updated risk analysis and new testing?
  • Does the UEF show clear links among hazards, tasks, controls, and evidence?
  • Do labeling and training reflect validated use, not untested workarounds?

FAQ

Is HFE mandatory?

Yes in effect. EU MDR/IVDR require design that minimizes use error (MDR Annex I Ch. I §5; Ch. II §14). In the U.S., FDA expects human factors in design validation (21 CFR 820.30) and often requires summative validation for critical tasks.

What counts as a “critical task”?

A task which, if performed incorrectly or omitted, could cause harm or lead to unacceptable risk; identify these from the ISO 14971 risk analysis and verify them in validation.

How many users are needed for summative testing?

It depends on risk and use diversity; however, regulators typically expect enough representative users to robustly cover all critical tasks and user groups described in the plan.

Do software-only devices need HFE?

Yes. SaMD/UIs must undergo the same risk-based usability process; align with IEC 62366-1 and software standards (e.g., IEC 62304) where relevant.

When should HFE start?

Early. Begin during requirements and concept work, run iterative formative studies, and complete summative validation before final design freeze and submission.