Predicate Device

What makes a device a valid predicate?

A predicate must be legally marketed: cleared through a 510(k), granted through De Novo, or grandfathered pre-amendments. A device removed from the market because it was misbranded or adulterated cannot serve. Applicants find candidates through the FDA's 510(k) database and the classification regulation for their product code.

What is substantial equivalence?

A new device is substantially equivalent when it has the same intended use as the predicate and either the same technological characteristics, or different characteristics that raise no different questions of safety and effectiveness — supported by performance data showing the device is at least as safe and effective. Substantial equivalence is a comparative standard, which is precisely what makes predicate selection strategic: the choice fixes the intended-use frame and the testing expectations for the entire submission.

Can multiple predicates be used?

Yes, with care. A primary predicate establishes intended use; reference devices can support specific technological characteristics. What the FDA discourages is "split predicates" — combining one device's intended use with another's technology to bridge a gap neither could close alone.

What are the risks of a weak predicate choice?

A predicate with an outdated technology baseline can force testing against expectations that no longer fit, and a strained equivalence argument can end in a not-substantially-equivalent decision — after which the realistic options are a De Novo request or a redesign of the submission strategy. Predicate strategy is where most United States 510(k) programs are actually won or lost, usually before any testing begins.