Page 210 - Safety Risk Management for Medical Devices

Benefit Risk Analysis 189

the disease is diagnosed earlier in the course of the disease. It may be that the
benefit is experienced by only a small subset of patients in the target popula-
tion. Or conversely the benefit may be experienced by a large population.
• Duration of the benefit—Some treatments are curatives, while others may be only
short term. The longer the benefit persists, the more the benefit would be val-
ued when balancing the benefit against risk.

Patients are an important source of input on the determination of benefit risk
balance. They have an intimate and personal understanding of what it is like to live
with a disease and how a device would impact their daily life. Ultimately, it is the
patient who takes the risk for the promise of the benefit of a device.
The estimation of residual risks of a medical device is the domain of risk manage-
ment, which is covered in detail in this book. Residual risk estimation can be quanti-
tative or qualitative. Both clinical and nonclinical methods can be used to confirm
estimations of risks, and the effectiveness of implemented Risk Controls.
When risk estimation is subjective and qualitative, the following factors are
considered:
• Severity, type, likelihood, and duration of Harms—These are Harms that are caused
by the use of the device. Risk management estimates the severity and likeli-
hood of the Harms. Some Harms last a short while, such as a skin cut. But
other Harms may last a long while. For example, brain damage would last a
lifetime.
• Procedure-related Harms—Some Harms are not caused by the device, but are
incidental. For example, implanting a medical device requires surgery, and sur-
gery always presents risks of Harm.
When judging the risk versus the benefits of a device, additional factors that are
considered by the FDA are:
• Quality of the clinical data—Poorly designed and executed clinical investigations
could render the results of the investigation unreliable and weaken the argu-
ment of the dominance of benefit over risks.
• The disease characteristics—Factors considered are: whether the disease is degen-
erative and untreated worsens over time, or, is it stable, or does it get better
over time; these make a difference in the judgment of the benefit risk
balance.
• Patient risk tolerance—The degree of risk tolerance varies greatly among patients
and for different diseases. Patients with very severe diseases where the risk of
dying is imminent may tolerate higher risks. For chronic diseases where
patients learn to adapt to the presence and management of the disease, risk tol-
erance may be lower.