Of the 56,683 Premarket Approval (PMA) records FDA has issued for high-risk medical devices, only 1,470 — 2.6% — are original approvals. The other 97.4%, more than 55,000 filings, are supplements: incremental changes to devices already on the market. In the most recent full year in 2024, the ratio was even more lopsided — 33 original approvals against 2,197 supplements, a 67-to-1 supplement-to-original rate. This is not a rounding error in FDA's filing system. It is the operating model of the implantable-device industry.
Why the ratio looks like this
A PMA supplement exists because 21 CFR 814.39 lets a device sponsor amend an approved device — a new material, a firmware update, a manufacturing-site change, a labeling tweak — without re-running the full premarket approval process that the original device required. Three supplement tracks dominate the PMA record: 30-Day Notice (27,592 filings, for manufacturing/method changes that don't affect safety/effectiveness), Normal 180-Day Track (9,907, for design or labeling changes), and Real-Time Process (7,157, for minor changes reviewed while the sponsor is on-site). A 30-day notice can clear in a month; an original PMA typically takes a multi-year clinical program to support it. Once a device platform is approved, the economically rational move for a manufacturer is to keep that platform alive through supplements rather than fund a new original PMA from scratch — each supplement is cheaper, faster, and reuses the safety/effectiveness base already on file.
The single most-supplemented record illustrates the pattern at the extreme: P980016, Medtronic's implantable cardioverter-defibrillator (ICD) platform, has accumulated 926 supplements across 29 years (1998–2026) — more filings than the entire population of original PMAs approved in most individual years of our dataset. Medtronic devices account for seven of the ten most-supplemented PMA numbers in the index: five cardiac rhythm management products (ICDs, CRT-Ds, a pacemaker pulse generator, and leads) and two neurostimulators, including P840001, the Itrel spinal cord stimulator, with 606 supplements since 1984. This concentration matches a peer-reviewed finding: a study of cardiac implantable electronic devices approved 1979–2012 found FDA approved 77 original PMAs versus 5,829 supplement PMAs for this device category — a median of 50 supplements per original approval (Rome et al., JAMA, 2014).
What this data does not tell us
FDA's public PMA database (56,683 records) and does not capture 510(k) clearances, which cover the large majority of moderate-risk devices through an entirely separate pathway — so this analysis is scoped to the highest-risk device class only. Supplement_type is missing or blank for 3,355 records (5.9%), and decision-date coverage is thin before 1979, reflecting FDA's own historical digitization gaps rather than actual approval activity. We also cannot distinguish, from structured fields alone, a safety-driven supplement from a purely commercial line-extension — that requires reading the supplement_reason text field record by record.
Why this matters
The supplement pathway is why mature device categories — ICDs, spinal stimulators, orthopedic implants — consolidate around a small number of long-lived platforms rather than fragmenting into many one-off approvals. For device-maker R&D economics, it means the payoff to winning an original PMA compounds for decades: each subsequent iteration is a fraction of the cost of the first. For competitors and new entrants, it means the real barrier isn't the initial approval bar, it's the multi-decade supplement runway an incumbent can ride once they clear it.