What is a predicate device?

A predicate is the legally-marketed device that a new 510(k) submission claims substantial equivalence to. Almost always, the predicate is itself a previously-cleared 510(k) device. A submission without a valid predicate cannot clear via the 510(k) pathway.

Can any cleared device be used as a predicate?

No. The predicate must (1) be legally marketed, (2) share the same intended use as the new device, and (3) either share the same technological characteristics or have different characteristics that do not raise new questions of safety and effectiveness. A predicate that has been withdrawn for safety reasons cannot be used.

What is a predicate chain?

The backward lineage of predicates. Device A is cleared because of predicate B, which was cleared because of predicate C, and so on — eventually tracing to devices legally marketed before the 1976 Medical Device Amendments that created the 510(k) pathway. Every cleared device sits at the end of such a chain.

What is a reference device, and how is it different from a predicate?

A reference device is a legally-marketed device used to support specific performance claims in a 510(k) submission, but it is not the basis of substantial equivalence. The predicate establishes SE; reference devices support individual technology or safety arguments within the submission.

Are predicate devices listed in FDA databases?

Only sometimes. FDA does not publish a structured predicate field in openFDA. Predicates are disclosed in the 510(k) Summary PDF (when the applicant chose summary over statement), but many recent summaries are image-only scans and older records may have no published summary at all. Reconstructing a full predicate chain often requires manual PDF review.

Understanding Predicate Devices

A predicate device is the legally marketed device that a new 510(k) submission claims to be substantially equivalent to. Every cleared device has at least one. Most have exactly one. Some have several.

If you are researching a specific K-number and want to know what it was predicated on, the information lives in the public 510(k) summary for that clearance — sometimes as a single K-number citation, sometimes a list, sometimes narrative prose. FDA does not expose predicate relationships as structured fields in the openFDA API; you read them out of the summary document. A browsable predicate chain is on the roadmap for this site.

Why predicates matter

The entire substantial-equivalence argument rests on them. When an applicant files a 510(k), the case they have to make is:

Same intended use as the predicate.
Same technological characteristics, or different characteristics that do not raise new questions of safety and effectiveness — supported by performance data.

If either prong breaks, the predicate is unusable. The applicant either picks a different one or exits the 510(k) pathway altogether.

How predicates are chosen

Good predicate selection is a regulatory craft. The common patterns:

Same manufacturer, previous generation. Easy SE argument, because the technologies are often nearly identical. Common for line extensions and minor design updates.
Same product code, major competitor. Forces a more detailed differences analysis. Often picked when the applicant has no prior K-number in the space.
Multiple predicates for different feature sets. One predicate supports the intended-use argument. A second supports a specific technological element (a new sensor, a different algorithm, a new material).

FDA allows multiple predicates. The 2014 guidance document The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications is the authoritative walkthrough. It is still the reference most RA professionals cite.

Predicate chains

This is where things get interesting. Device A is cleared based on predicate B. B was cleared based on predicate C. C was cleared based on D. Keep going back, and eventually you hit a preamendments device — one legally marketed before the 1976 Medical Device Amendments that created the 510(k) pathway.

The chain can be long. A modern pulse oximeter cleared in 2026 might trace back through eight or ten intermediate predicates to an analog oximeter legally marketed in 1975.

This is a double-edged legal feature:

It lets innovation build incrementally. Manufacturers don't re-run safety testing from scratch each generation.
Each generation can drift. Small changes compound. By generation eight, you can have a substantively different device still "equivalent" to something from the disco era.

FDA has acknowledged the drift problem publicly. The Medical Device Safety Action Plan put predicate age under closer scrutiny. The practical effect inside industry: reviewers push back harder on long chains where the newest device is materially different from its earliest ancestor.

Reference devices are not predicates

A reference device is cited in a 510(k) for a different purpose: not to establish substantial equivalence, but to support specific performance data.

Example. A new sleep-apnea monitor has a pulse-oximeter module. The predicate is another sleep-apnea monitor. The reference device is a standalone pulse oximeter whose performance data the applicant cites for that module. FDA expects the two to be clearly distinguished in the submission. Mixing them up is one of the more common documentation errors.

Working backward from a device

If you are on a device detail page on this site and want the predicate story, for now the flow is manual:

Click through to the openFDA record for that K-number (linked at the bottom of every page).
Open the 510(k) summary URL from the statement_or_summary field, when populated.
Find the predicate citation in the narrative.

It is a slog. The predicate chain browser on the roadmap will close that loop: click a K-number, see the full ancestry and descendants as a navigable tree.

Frequently asked questions

What is a predicate device?: A predicate is the legally-marketed device that a new 510(k) submission claims substantial equivalence to. Almost always, the predicate is itself a previously-cleared 510(k) device. A submission without a valid predicate cannot clear via the 510(k) pathway.
Can any cleared device be used as a predicate?: No. The predicate must (1) be legally marketed, (2) share the same intended use as the new device, and (3) either share the same technological characteristics or have different characteristics that do not raise new questions of safety and effectiveness. A predicate that has been withdrawn for safety reasons cannot be used.
What is a predicate chain?: The backward lineage of predicates. Device A is cleared because of predicate B, which was cleared because of predicate C, and so on — eventually tracing to devices legally marketed before the 1976 Medical Device Amendments that created the 510(k) pathway. Every cleared device sits at the end of such a chain.
What is a reference device, and how is it different from a predicate?: A reference device is a legally-marketed device used to support specific performance claims in a 510(k) submission, but it is not the basis of substantial equivalence. The predicate establishes SE; reference devices support individual technology or safety arguments within the submission.
Are predicate devices listed in FDA databases?: Only sometimes. FDA does not publish a structured predicate field in openFDA. Predicates are disclosed in the 510(k) Summary PDF (when the applicant chose summary over statement), but many recent summaries are image-only scans and older records may have no published summary at all. Reconstructing a full predicate chain often requires manual PDF review.

Last updated 2026-04-23.