Predicate Device

The new device must share the same intended use as the predicate. The FDA evaluates this through the Intended Use Statement and Indications for Use, comparing the clinical purpose, patient population, anatomical site, and disease condition. Any expansion of the intended use—such as diagnosing a new condition or targeting a different anatomical region—breaks substantial equivalence and may require a De Novo Classification Request.

• Compare general intended use (e.g., diagnostic, therapeutic, monitoring)
• Match specific indications including patient demographics and clinical context
• A new intended use invalidates the predicate comparison entirely
• Differences in technological characteristics are acceptable if they do not affect safety or effectiveness

The FDA requires a detailed side-by-side comparison of technological characteristics between the new device and the predicate. Differences are permissible only if they do not raise new questions of safety or effectiveness. For SaMD, this includes comparing algorithm architecture, input data types, output formats, and software platform dependencies. Performance testing must demonstrate that any technological differences do not adversely impact diagnostic accuracy.

• Document design features, materials, and operating principles
• For SaMD: compare algorithm class, input modalities, and output specifications
• Any new technological feature must be validated through bench testing or analytical validation
• Significant technological differences may require clinical data to support equivalence

A single predicate device is the preferred and most straightforward path for establishing substantial equivalence. However, the FDA permits a split predicate approach when the new device combines features from multiple legally marketed devices. In a split predicate, the intended use must match the primary predicate, while technological characteristics may reference a secondary predicate. This approach requires careful justification to demonstrate that combining features does not introduce new risks.

• Single predicate: one device serves as the complete reference
• Split predicate: intended use from one device, technology from another
• Split predicates require additional rationale for feature combination
• The FDA scrutinizes split predicates more closely for potential interaction effects

The 510(k) submission must provide clear traceability to the predicate device, including its 510(k) number, trade name, and manufacturer. The Substantial Equivalence (SE) comparison table is the central document mapping each feature of the new device to the predicate. For SaMD, this includes software version history, algorithm change logs, and Verification and Validation (V&V) evidence demonstrating equivalent performance.

• Include the predicate's 510(k) number and clearance date
• Provide a line-by-line comparison table of indications, technology, and performance
• Reference the predicate's Design History File (DHF) structure where applicable
• Maintain a regulatory rationale document justifying predicate selection

The core legal standard of the 510(k) pathway. A new device is substantially equivalent if it has the same intended use and the same technological characteristics as the predicate, or any different technological characteristics do not raise new questions of safety and effectiveness. Demonstrating SE typically requires side-by-side bench testing, analytical validation, and sometimes clinical data comparing the new device's performance to the predicate's established profile.

A formal declaration that anchors the entire predicate comparison. The intended use defines the general purpose of the device, including the disease or condition it diagnoses, treats, or prevents. A new device must share the same intended use as its predicate. Key elements include:

• The medical purpose (e.g., detection, diagnosis, monitoring)
• The target condition or disease state
• The patient population
• The anatomical site or specimen type

A precise, granular description of the clinical context for device use, distinct from the broader intended use. The indications for use specify the exact patient demographics, anatomical regions, and clinical scenarios where the device is validated. When selecting a predicate, the new device's indications for use must fall within the predicate's cleared indications. Expanding indications beyond the predicate typically requires a different regulatory pathway.

The regulatory submission vehicle through which a manufacturer demonstrates substantial equivalence to a predicate device. A complete 510(k) package includes:

• Identification of the predicate device with its 510(k) number
• A detailed comparison table of technological characteristics
• Performance testing data (bench, analytical, and clinical as needed)
• Biocompatibility and sterilization documentation where applicable
• Proposed labeling mirroring the predicate's format

The regulatory pathway for novel devices of low to moderate risk that lack a legally marketed predicate. When no suitable predicate exists, manufacturers cannot use the 510(k) route and must instead submit a De Novo request. If granted, the device becomes a new classification regulation and can serve as a future predicate for subsequent 510(k) submissions. This pathway is increasingly relevant for AI-driven diagnostic tools with no clear predecessor.

The FDA's most stringent review process, required for Class III high-risk devices that cannot use the 510(k) or De Novo pathways. Unlike the comparative 510(k) framework, PMA demands independent demonstration of safety and effectiveness through extensive clinical investigations. If a predicate device was cleared via PMA, any new device claiming substantial equivalence must meet the same rigorous evidentiary standard, making PMA predicates significantly harder to leverage.