Page 179 - Safety Risk Management for Medical Devices

158 Safety Risk Management for Medical Devices

Qualitative severity
Negligible Moderate Significant

High
Qualitative probability Medium

Low

Figure 17.1 Example 3 3 3 qualitative risk matrix.

Table 17.1 Example three-level definitions for severity
Term Definition
Significant Death or permanent impairment/injury
Moderate Reversible or minor injury
Negligible Discomfort or inconvenience

Table 17.2 Example three-level definitions for probability
Term Definition
High Likely to happen | often | frequent
Medium Can happen, but not frequently
Low Unlikely to happen | rare | remote

Each Hazard would have an estimated risk based on the available data for the
probability of occurrence of Harm, and the estimated severity of that Harm.
ISO 14971 [3,7] offers a 5 3 5 example for ranking severity and probability. These
examples are cited in Tables 17.3 and 17.4.

Table 17.3 Example five-level definitions for severity
Rank Term Definition
5 Catastrophic Death
4 Critical Permanent impairment or life-threatening injury
3 Serious Injury or impairment requiring professional medical intervention
2 Minor Temporary injury or impairment not requiring professional medical
intervention
1 Negligible Discomfort or inconvenience or no harm