Why do so many 510(k)s face friction in review?

In short: Industry estimates vary by definition: roughly 10–15% of 510(k)s face final rejection, while broader figures — counting any Additional Information request or hold at any point — run as high as 64–69% by some industry estimates. Predicate mismatch and documentation gaps are the most common causes, and both are preventable before submission.

Why the numbers spread so widely

The range you'll see cited across the industry depends entirely on what's being counted. A narrower measure — devices that never clear at all — sits in the 10–15% range by most estimates. A broader measure — any submission that receives at least one Additional Information request, hold, or refuse-to-accept notice at any point during review, even if it eventually clears — runs much higher: roughly 64%, per The FDA Group's analysis of 510(k) submission outcomes, a life sciences regulatory consultancy that tracks FDA premarket submission patterns, with other industry sources citing figures as high as 69%. Both numbers are describing real, different things; neither is wrong, but citing either without the definition — and a source you can actually check — attached is misleading. It helps to keep three distinct events apart: a Refuse-to-Accept notice is a completeness screen before substantive review starts, an Additional Information request is a substantive hold during review, and a final not-substantially-equivalent decision is an actual rejection — the broad "any friction" figures blend all three.

The broad industry range is consistent with FDA's own published data: FDA's MDUFA performance reporting shows the agency issued a first-review-cycle Additional Information request for 63–68% of 510(k)s submitted in FY2018–FY2022. One caveat still worth flagging directly: those cohorts pre-date FDA's mandatory eSTAR submission template and tighter acceptance screening, which industry commentary credits with materially reducing Refuse-to-Accept rates from historical levels — so treat the 64–69% range as a prompt to check FDA's latest MDUFA performance report or FDA-TRACK dashboard before leaning on it for anything decision-critical, not as settled current truth.

What actually causes friction, regardless of which number you use

Two causes account for most of it. A shaky equivalence argument — FDA isn't convinced your comparison device actually shares your intended use or technological characteristics closely enough — generates the most substantive Additional Information requests, since the agency has to ask you to justify a comparison that doesn't hold up on its own. Documentation gaps — missing or incomplete software V&V evidence, cybersecurity documentation, or testing data — generate the most administrative holds, the kind that are entirely preventable with a more complete initial submission.

What friction actually costs, and what avoids it

An Additional Information hold pauses FDA's review clock until you respond, typically adding weeks to several months depending on how substantive the request is — a real cost, but rarely a permanent no. A Pre-Submission meeting before you file is the most reliable way to surface predicate or testing gaps while they're still cheap to fix, converting guesswork into documented FDA feedback before your formal clock even starts. "Submission-ready before you submit" is the practical framing worth adopting.

Where next: Why Most 510(k)s Get an Information Request · What is an FDA Pre-Submission (Q-Sub), and should I do one?

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