Page 209 - Safety Risk Management for Medical Devices

188 Safety Risk Management for Medical Devices

Benefits of a device are presumed under the condition that the device works reli-
ably, as intended. Risks and benefits are not the same for everyone. The same medical
device could provide varying degrees of benefit to different patients and pose different
levels of risks. Many factors are responsible for this, e.g., variability of the physiology
and circumstances of a patient, environmental variability, and variability in
manufacturing the medical device itself.

The FDA has published three guidance documents to help with the determination
of benefit risk balance for medical devices:

2 Factors to Consider When Making Benefit-Risk Determinations in Medical
Device Premarket Approval and De Novo Classifications [29]
2 Benefit-Risk Factors to Consider When Determining Substantial
Equivalence in Premarket Notifications [510(k)] with Different
Technological Characteristics [30]
2 Factors to Consider When Making Benefit-Risk Determinations for Medical
Device Investigational Device Exemptions (IDEs) [31]
In general, the FDA expects the manufacturer to provide a “reasonable assurance
of safety and effectiveness” by “weighing any probable benefit to health from the use
of the device against any probable risk of injury or illness from such use.”
Establishment of benefits is typically done by clinical evaluations. These are formal,
well-planned investigations with defined end-points to show with statistical validity,
the benefits of a medical device. See Annex X of the MDD [4] for further guidance
on Clinical Evaluations. Sometimes nonclinical evaluations can be used to establish
benefit. For example, animal- and cell-based testing, usability testing, and computer
modeling and simulations.
Factors that are considered to evaluate the benefits of a device include:

• Type of benefit—Medical devices provide a variety of benefits. For example:
• improving quality of life
• reducing the probability of death
• aiding improvement of patient function
• reducing the probability of loss of function
• providing relief from symptoms
• Magnitude of the benefit—This is typically measured against a scale according to
specific criteria. For example, for Parkinson’s disease the patients are asked to
walk for 6 minutes. The longer the distance walked, the higher the magnitude
of the benefit.
• Probability of the benefit—Not all patients receive the intended benefit.
Sometimes it is possible to predict which patients are more likely to benefit
from a given therapy. For example, a cancer therapy may be more effective if