Final answer:
A major difference between an HDE and a PMA application is that an HDE does not require the demonstration of effectiveness like a PMA does, due to the small population targeted by the device.
Step-by-step explanation:
The major difference between an HDE (Humanitarian Device Exemption) and a PMA (Premarket Approval) application lies in effectiveness requirements. An HDE is intended for devices that treat or diagnose diseases or conditions that affect fewer than 8,000 individuals in the United States per year.
Since these devices are meant for use in small populations where gathering clinical evidence would be difficult due to the rarity of the condition, the FDA does not require the demonstration of effectiveness that would be required for a PMA.
Instead, the device must demonstrate safety and probable benefit. In contrast, a PMA is the most stringent type of device marketing application required by the FDA, and it requires a manufacturer to prove reasonable assurance of both the safety and effectiveness of a device before it can be sold.