Predicate Devices: Find the Right One for Your 510(k) — and Avoid a Hold Letter

2026-08-23 · Caduvo Team

What a predicate device is and how to search the FDA 510(k) database to find one. A practical workflow for ranking candidates, matching intended use, and avoiding the split-predicate trap that triggers hold letters.

You can’t submit a 510(k) without naming a predicate device. Whether you pick one device or three, the choice determines your testing requirements, your review clock, and the scope of your clearance. Get it wrong and FDA issues an Additional Information request that resets the clock. Get it really wrong and you get a Not Substantially Equivalent letter.

The phrase what is a predicate device is often answered with a textbook definition. This post answers it with a workflow. Here’s how to find candidates, rank them, and avoid the split-predicate trap.

What Is a Predicate Device?

A predicate device is a legally marketed device to which you claim substantial equivalence in a 510k submission. It doesn’t need to be identical to your device. It needs to have the same intended use and technological characteristics that don’t raise new questions of safety and effectiveness. Differences are acceptable if you can show — usually through bench testing, biocompatibility, or animal data — that they don’t alter the device’s safety and effectiveness profile.

Key point: FDA only considers devices that were cleared through a 510(k) clearance or were legally marketed before May 28, 1976 (preamendments devices). Devices cleared via the De Novo pathway can also serve as predicates for subsequent 510(k)s, but PMA-approved devices cannot.

A strong predicate shares your device’s:

A weak predicate forces you to document and close more gaps, adding weeks or months to your submission timeline.

How to Search FDA Databases for Predicate Candidates

Don’t start with a broad Google search. Start inside the FDA 510(k) database, which contains all cleared premarket notifications since 1976. The workflow takes about 90 minutes for a thorough first pass.

  1. Identify the right product code. FDA groups devices by regulation number, and each regulation maps to a three-letter FDA product code. Search the Product Classification Database at accessdata.fda.gov with keywords that describe your device’s clinical function. Pull the regulation number and product code for every match.
  1. Open the 510(k) Premarket Notification database. Filter by the product code(s) you identified. Sort by decision date descending. You’re looking for devices cleared in the last 5-7 years — older predicates can work, but they often rely on outdated test standards and may trigger reviewer questions about whether current science supports the comparison.
  1. Download the 510(k) summary for each candidate. FDA requires every 510(k) holder to post a summary statement that describes the device and the predicate used. Those summaries are gold: they state the intended use, comparison tables, and testing performed. Read at least 10 summaries for your target product code. You’ll notice patterns — which tests are standard, which differences FDA accepted, and which predicates appear repeatedly.
  1. Check labeling. Look for the cleared device’s IFU, operator manual, or promotional materials online. Compare their stated indications to yours. A one-sentence difference in intended use can shift your device into a different product code — or require a clinical study.

Criteria for Ranking Predicate Candidates

Once you have a list of 5-10 candidates, rank them on these five factors. Weight the first two highest.

Intended use overlap. Your intended use should be a subset of the predicate’s cleared indication, not an expansion. If the predicate is cleared for “fixation of fractures in long bones” and your device is for “fixation of fractures in the radius and ulna,” that’s a clean match. If your device adds a new anatomical site, you’re looking at a split predicate or additional testing.

Technological similarity. Map every design input to the predicate’s design. Same material? Same power source? Same software architecture? For each difference, list the specific standard (ISO, ASTM, IEC) or test method you’ll use to bridge it.

Clearance date. Predicates cleared since 2020 give you a more predictable path. FDA reviewers are familiar with recent submissions and the testing standards they reference. Older predicates increase the chance that an examiner will ask for modernized test data.

Testing burden visible in the summary. A good predicate’s 510(k) summary lists testing you can replicate: biocompatibility per ISO 10993, sterilization validation, electrical safety per IEC 60601, software documentation per IEC 62304. Count the test categories. If your device requires substantially more testing than the predicate did, it’s a signal that your changes might not qualify as SE.

Single-predicate vs. split-predicate path. A single predicate that covers your intended use and most of your technology is always the best-case scenario. A split predicate — using one device for intended use and a different device for a technological feature — is technically allowed but adds complexity. FDA must agree that the combination of references supports SE without raising new questions. If you can avoid a split, avoid it.

The Risks of a Weak or Split Predicate

Choosing a predicate with a different intended use or a fundamentally different energy source is the fastest way to a drawn-out review. The reviewer will issue a hold letter requesting additional performance data — often animal studies or clinical data — to demonstrate that the differences don’t affect safety and effectiveness. That hold letter stops the 90-day review clock.

A split predicate multiplies this risk. You now have to establish that combining features from two legally marketed devices doesn’t create new risks. FDA’s 2014 guidance on the 510(k) Program (still current) explicitly states that split predicates “may raise significant concerns” if the combination produces a device that’s meaningfully different from either predicate alone.

Companies sometimes reach for a split predicate when their device introduces a novel feature — a new coating, a wireless communication protocol, an AI-driven alarm — and no single cleared device includes it. The better move is to find a single predicate that matches 80-90% of your device’s design, then use that predicate to frame the novel feature as a minor modification demonstrated through bench testing. If that doesn’t work, you may need to consider whether the De Novo pathway is a better fit than a 510(k).

Also watch for predicates that were cleared with “indications for use” statements written broadly enough to cover a wide range of devices but not specific enough to match yours. A broad IFU on a 510(k) summary doesn’t mean FDA will accept any application that cites it. Reviewers will look at the actual device description, testing, and labeling precedent.

One practical check: before locking in a predicate, call your lead reviewer (once a submission is assigned) or use a Pre-Submission meeting to confirm your predicate selection and testing plan. FDA’s feedback at that stage—even a 15-minute teleconference—can save resubmission rounds.

Summary: What to Do Next

Caduvo’s platform flags predicate candidates tied to your device classification, maps product codes, and pulls relevant 510(k) summaries into one search interface. This shortens the 90-minute manual workflow to minutes. But the principles above apply whether you run the search yourself or use a tool to accelerate it.

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