Can an IVD device qualify for HUD designation if the affected patient population is fewer than 4,000 per year but each patient may need to be tested multiple times?

IVD devices qualify for an HUD designation when the number of persons tested
with the device is fewer than 4,000 per year. FDA recognizes that the number of
tests with the device may exceed one per patient. A device that involves multiple
patient uses may still qualify for HUD designation as long as the IVD device is
designed for diagnosis or treatment of a total of fewer than 4,000 patients per year
in the US.
If a device is being developed to diagnose or to help diagnose a disease or
condition with an incidence of fewer than 4,000 patients per year, but there are
more than 4,000 patients a year “at risk” who would be subject to testing using the
device, then the device may not qualify as a HUD. 21 CFR 814.102(a)(5).