Page 238 - Safety Risk Management for Medical Devices

Relationship Between ISO 14971 and Other Standards 217

Given the risk acceptance criteria and P2 numbers, the maximum probability of
the Hazard and thereby probability of use-failure (P) can be derived. Additionally,
there can be a “Company” policy that R, the probability of detecting a use-failure in
a summative test must be e.g., $ 90%. With these two pieces of information, the
number of participants can be derived. For example: Let’s say max tolerable P is 10%,
and R, per “Company” policy is 90%. The number of participants, n computes to 22.
You can also use table K.1 in Ref. [34] for the same purpose.
Another input from Risk Management to Usability Engineering is the indication of
areas of the UI that are not safety related, thereby enabling Usability Engineering to use
expert reviews, rather than conduct new summative tests, for minor changes to those areas.
The contribution of Usability Engineering to Risk Management is both in the
identification of use-failures which could result in Hazards, and in the performance of
summative studies which can serve as verification of effectiveness of Risk Controls.

29.4 INTERACTION WITH ISO 14155

ISO 14155 [33] is about clinical investigation of medical devices in human subjects.
ISO 14155 [33] makes a normative reference to ISO 14971 [3,7] and requires that
prior to the conduct of clinical investigations, the risks associated with the use of
medical devices in clinical investigations be estimated according to ISO 14971 [3,7].
ISO 14155 [33] states that the terms: clinical investigation, clinical trial, and clini-
cal study are synonymous. As such, these terms are used interchangeably herein.
In a clinical investigation, risks can be viewed over two horizons: prestudy and
poststudy. Before the study, risk management per ISO 14971 [3,7] serves to identify
the Hazards to the study participants, estimate the risks, control the risks, and do
benefit risk analysis. In this capacity, risk management behaves as a predictive
engineering tool. After the study has begun, risk management is reactive to Adverse
Events and attempts to minimize any Harms to the study participants.
There is a bidirectional flow of information between risk management and clinical
investigations. In fact, clinical investigations are a part of the risk management process.
Flow of information from risk management (ISO 14971) to clinical investigations
(ISO 14155):
• Identification of Hazards; estimation of risks; control of risks
• Identification of potential Harms, their nature, severity, probability, and
duration
• Information-for-safety, warnings, cautions
• Acceptability of benefit risk profile
• Any special risk areas on which the clinical study should focus
• The risk management report