IEC 62366 use-error severity

FAQ

What is a use error under IEC 62366-1?

IEC 62366-1 defines a use error as a user action or lack of action that was different from that intended by the manufacturer and that caused a different result. Use errors are analyzed in the usability engineering process and fed into the risk management file; they are not the same as abnormal use (intentional misuse outside the indicated use).

How does IEC 62366-1 connect to ISO 14971?

IEC 62366-1 usability engineering identifies use-related hazards, hazardous situations and use errors. The severity and probability of the resulting harm are evaluated and controlled under ISO 14971. Risk controls may include inherently safe design, protective measures, and information for safety / training, in that priority order.

When does a use scenario need summative human-factors validation?

Scenarios that can lead to serious injury or death, or that involve critical tasks where users cannot detect or recover from the error, typically need summative (validation) usability testing with defined success criteria, not formative interviews alone. FDA’s human-factors guidance for medical devices expects residual use-related risk to be acceptable after those controls and tests.

Why do detection and recovery matter in the score?

If the user or system cannot detect the error in time, harm can accumulate silently. If they cannot recover without specialized intervention, a single error may proceed to harm. Both factors increase residual risk and usually drive design or alarm changes before you argue that information for safety is enough.

Is delay to therapy a clinical harm?

It can be. When the indication is time-sensitive, delay to therapy or diagnosis is often treated as a clinical harm in the ISO 14971 file even if no immediate tissue injury occurs. Document the clinical rationale rather than filing delay as a pure nuisance.

Does this helper replace a usability engineering file?

No. IEC 62366-1 expects a usability engineering file covering the use specification, user interface characteristics, known use-related hazards, formative evaluations, and summative validation where required. This page scores a single hazardous use scenario for triage.