What Is a Predicate Device — and What Happens When You Don't Have One?

A predicate device is the legally marketed device you compare your own device against in a 510(k). Everything in a premarket notification hangs off it. Pick the right one and the submission writes itself. Pick a convenient one and you will spend months answering questions you created.

What substantial equivalence actually requires

FDA finds a device substantially equivalent when it has the same intended use as the predicate and either the same technological characteristics, or different technological characteristics that do not raise different questions of safety and effectiveness — with performance data showing the device is at least as safe and effective as the predicate.

Read that carefully, because two words do most of the work.

Same intended use is stricter than same clinical area. A device that measures the same physiological parameter but makes a diagnostic claim where the predicate made a monitoring claim does not have the same intended use. Teams lose here constantly.

Different questions of safety and effectiveness is the technology test. You are allowed different technology. You are not allowed technology whose differences introduce risks the predicate's testing never addressed without data that answers them.

The predicate must also be legally marketed: a device cleared through 510(k), a device granted through De Novo, a preamendments device, or one reclassified into Class I or II. A device withdrawn for safety reasons is not a valid predicate.

Searching properly

Start in the FDA product classification database and find the regulation and product code for your device type. Then search the 510(k) database by product code, not by company name or by keyword from your pitch deck.

Open the actual 510(k) summaries. They tell you the indications for use language FDA accepted, the technological comparison the sponsor made, and the performance testing that supported it. That is your template. A predicate you have not read the summary for is not a predicate; it is a hope.

Two useful filters as you go: how recent the clearance is, and whether the device type has an FDA guidance document setting out expected testing. Recent clearances in a guidance-covered product code are the easiest submissions to build.

Split predicates, reference devices, and where teams go wrong

You may cite more than one device, but only in specific ways.

A primary predicate carries the intended use comparison. Additional predicates can support the technological comparison where your device combines features from more than one cleared product — as long as the intended use remains consistent.

What you may not do is a split predicate: taking the intended use from one device and the technology from another with a different intended use. FDA rejects this.

A reference device is different again. It is a legally marketed device cited to support scientific methodology or performance testing — not to establish equivalence. Used correctly it strengthens a submission. Used as a substitute for a real predicate it gets you a not-substantially-equivalent decision.

Two traps worth naming

Predicate creep. Each generation of device is cleared against the last, and over several cycles the product drifts a long way from the original predicate. Each step looked defensible; the cumulative distance is not. If your predicate was itself cleared against a predicate that was cleared against another, trace the chain and check the original intended use still matches yours.

Recalled or withdrawn predicates. Check the recall and safety-communication history of any device you intend to cite. Building an argument on a device with a Class I recall for the very failure mode you share is a predictable problem, and FDA will raise it.

When there is no predicate

If the search is honest and nothing fits, you have four options.

De Novo classification. For low to moderate risk devices with no predicate, this is the intended route. FDA creates a new classification with special controls, and your device becomes the predicate for everyone who follows. It usually needs more clinical or validation evidence than a 510(k) and takes longer, but it is far cheaper than a PMA and it hands you a defensible market position. Our pathway selection article covers when this is the right call.

Reclassification. If an existing device type is classified more restrictively than current evidence supports, a reclassification petition can move the type — a long play, occasionally worth it for a category leader.

Redesign to fit. Sometimes the cleanest answer is narrowing the intended use so an existing regulation and predicate apply, launching, and expanding claims later with data you collected on the market. Unglamorous and frequently the fastest route to revenue.

PMA. If risk cannot be managed with special controls, the absence of a predicate is not the problem — the class is. See our 510(k) versus PMA comparison for what that route costs.

Before choosing, use FDA's Q-Submission programme to put the question to the review division directly. A pre-submission meeting costs a few months and can save a year of building the wrong file.

Three things to do this month

Write your indications for use statement in one sentence, then search the 510(k) database for clearances whose accepted language matches it. If nothing matches, you have your answer about the pathway.

Read three full 510(k) summaries in your product code and list the performance testing each one relied on. That list is your test plan.

Check the recall history of every candidate predicate before it enters a slide.

If you are planning launches beyond the US, run the same exercise against the EU MDR and UKCA requirements — the classification logic differs and a predicate has no meaning there. MedTech Compass scores regulatory route and payment route side by side across 25+ markets, and DevicePath is our open-source starting point for regulatory triage.

Sources

1. FDA — The 510(k) Program: Evaluating Substantial Equivalence in Premarket Notifications (final guidance): https://www.fda.gov/media/82395/download 2. FDA — Premarket Notification 510(k): https://www.fda.gov/medical-devices/premarket-submissions-selecting-and-preparing-correct-submission/premarket-notification-510k 3. FDA — 510(k) Premarket Notification database: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/pmn.cfm 4. FDA — De Novo classification database: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpmn/denovo.cfm 5. FDA — Product Classification database: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfpcd/classification.cfm 6. FDA — De Novo Classification Request: https://www.fda.gov/medical-devices/premarket-submissions-selecting-and-preparing-correct-submission/de-novo-classification-request

This article summarises publicly available FDA guidance and databases. It is not legal or regulatory advice.