Effective patent time left: A reproducible legal-status metric for U.S. medical devices

The nominal patent term does not reveal how much patent protection remains when a regulated medical device receives U.S. marketing authorisation. Patent term adjustment, terminal disclaimers and, for eligible products, patent term extension alter that endpoint; the starting event differs among 510(k) clearance, De Novo classification and premarket approval. This article introduces Effective Patent Time Left (EPTL), an auditable legal-status metric joining the pathway-specific U.S. Food and Drug Administration authorisation date to the expiry of a matched utility patent. The EPTL inputs are public FDA and U.S. Patent and Trademark Office records, processed under an explicit source hierarchy and coding rules. A hand-checked core of 38 device products within the medical-device branch of 35 U.S.C. § 156(g)(3) demonstrates the metric; RECELL is reported separately because FDA treated it as a human biological device under § 156(g)(1)(B). In the core, the signed pre-extension balance averages 7.65 years and ranges from −0.49 to 13.49 years; after extension, the mean is 10.19 years. Five certificates reach the five-year extension cap, and eight post-extension endpoints reach the fourteen-year post-approval ceiling. Active FDA review days are distinguished from total calendar decision time, the data route is updated to the USPTO’s May 2026 patent-term-extension files, and maintenance-fee histories are audited. Every ordinary fee due date reached by authorisation showed payment, precluding estimation of a correlation in this selected series. EPTL converts heterogeneous FDA and patent records into a reproducible field for patent search, portfolio valuation and competitive intelligence, without treating earlier development or commercial activity as wasted.