510(k) predicate daisy-chaining lets devices drift from safety data

The FDA's 510(k) clearance pathway allows new medical devices to claim "substantial equivalence" to a predicate device, which itself may reference an older predicate, forming a chain that can stretch back decades. This means a device cleared in 2025 may ultimately trace its safety justification to a device from 1985 that was never clinically tested, because pre-1976 devices were grandfathered in. Patients end up implanted with devices whose real-world safety profile is extrapolated across 5+ generations of design changes, none of which individually triggered a full clinical trial. This persists because overhauling the 510(k) system would require congressional action, and the device industry lobby (AdvaMed) consistently fights reform since faster clearance timelines are a competitive advantage worth billions annually.