Medical devices play an increasingly prominent role in modern health care delivery. Medical devices that potentially pose an unreasonable risk of illness or injury (Class III devices) are currently approved by the US Food and Drug Administration (FDA) via 2 major regulatory pathways. Low- to medium-risk devices require evidence of substantial equivalence to a predicate device, as determined by the 510(k) process. High-risk devices require a confirmatory study to support a premarket approval (PMA) application based on valid scientific evidence that there is reasonable assurance that the device is safe and effective.