Substantial Equivalence Documentation: How to Select the Comparison Device

1. Key takeaways

Substantial equivalence (SE) in Korea is an element-by-element comparison exercise, with 6 comparison elements: intended use, mechanism of action (MoA), raw materials, performance, testing specifications, and instructions for use. The eligibility of the comparison device is a hard condition – it must be a product that has already obtained an item licence, item certification or item notification in Korea; an overseas registration certificate does not create comparison eligibility in Korea.

• Where all 6 elements hold, the product is treated as an equivalent device in the same category and may be exempt from parts of the technical documentation; where any element shows a significant difference, the product falls into the improved device or the new device category, and the documentation requirements rise accordingly. For in vitro diagnostic devices the comparison elements are 4: testing specifications and instructions for use do not apply.
• A failed comparison is not the end of the application. GRZAN handles failed comparisons through 3 remedial routes: replacing the comparison device, switching to the full technical documentation pathway, or supplementing performance data for the differing elements individually.

2. Legal basis

The instruments below set out the SE judgment criteria, the classification of new, improved and equivalent devices, and the IVD pathway that departs from the device rules. Regulatory information verified as of October 29, 2026.

Scope of application of the 6 comparison elements. The table shows which elements apply to medical devices and to IVDs respectively, and where comparisons most often lose points.

3. Expert insights

Comparison device eligibility means obtained in Korea, not marketed overseas. Holding an NMPA registration certificate, an EU CE certificate or a US 510(k) clearance does not create comparison device eligibility in Korea. The comparison device must be a product that has already completed one of the three acts in Korea – item licence, item certification or item notification. The first task GRZAN performs at project initiation is to search Korean public information for usable comparison devices and build a candidate list, rather than writing the comparison table first and searching for a subject afterwards. The candidate list should name at least 2 to 3 products: the primary comparison device is used for the application, and the backup comparison device allows an immediate switch if the primary comparison fails.

Among the 6 elements, the first to collapse is usually not raw materials but instructions for use. Differences in raw materials are easy to identify and companies prepare explanations proactively. The instructions-for-use element tends to fail at the last moment: when the usage, frequency and applicable population wording in the Chinese leaflet is translated literally into Korean, it no longer matches the labeling scope of the comparison device, and a previously sound equivalence fails on the final element. The GRZAN approach is to finalize the instructions for use and the labeling texts before the comparison table.

IVDs carry only 4 elements; copying the device table of 6 creates two pieces of wasted work. The IVD comparison does not apply to testing specifications and instructions for use, because the analytical performance and clinical performance of IVDs are governed by separate requirements, see Article 29: Independent pathway for IVD devices and clinical performance studies. Applying the 6-element device table directly to an IVD forces comparability arguments on two inapplicable elements, which itself invites a deficiency request.

The three remedial routes after a failed comparison – the order of choice determines the cost. The first route is replacing the comparison device: find a closer model within the same item group, or narrow the scope of the application to align with the comparison device. The second is switching to the full technical documentation pathway: complete the dossier against the 7 elements described in Article 21: Technical Document structure and its correspondence with IMDRF STED. The third is supplementing performance data for the differing elements individually (practical estimate: whether the data suffice to bridge the difference must be confirmed with the accepting authority in advance). The cost of the three routes rises in that order, but the order of choice depends on where the difference lies: where the difference is in intended use or mechanism of action, replace the comparison device first; where it is in raw materials, complete the technical documentation first; where it is only in performance, attempt the single-element bridge first. GRZAN recommends exhausting the first route before moving on.

4. Practical recommendations

• Build the candidate list before writing the comparison table. Search Korean public information for similar products that already hold a licence, certification or notification in Korea, assemble 2 to 3 candidate comparison devices, and pre-score them against the 6 elements before fixing the primary comparison device.
• Give the mechanism of action its own section, supported by data. The MoA element must describe the action pathway clearly and cite verifiable literature or proprietary test data; a bare conclusion is not acceptable.
• Manage the comparison table as a controlled document. Bring the comparison table version number under the master technical documentation versioning, so it can be reused directly at change filings and item updates.
• Align the comparison scope with the item group scope. The models covered by the comparison table must match the item group division, and models across groups each need independent justification. If the comparison conclusion covers only part of the models in the group, the remaining models must still be compared individually in later applications.
• File the comparison conclusion together with the pathway determination. Whether the product is an equivalent device, an improved device or a new device directly determines the review pathway; complete the self-assessment before filing, see Article 20: Pre-market pathway selection decision tree.

5. Verification checklist

• □ Comparison device eligibility: search Korean item licence, certification and notification records; one of the three already obtained in Korea and verifiable.
• □ All 6 elements complete: verify element by element (4 elements for IVDs); all 6 (4 for IVDs) carry a conclusion, none left blank.
• □ Intended use consistency: compare the use wording word for word with the comparison device; not broader than the comparison device scope.
• □ Mechanism of action argument: check the mechanism description and supporting data; supported by literature or proprietary data, not a purely textual conclusion.
• □ Raw material comparability: check material grades and suppliers; differences explained and without impact on safety and effectiveness.
• □ Testing specification basis: query whether the item has a Korean standard specification; direct mapping where one exists, documented justification where none exists.
• □ Instructions for use consistency: compare against the finalized Korean instructions for use; consistent with the labeling scope of the comparison device.
• □ Classification conclusion: self-assess against the three classification criteria; conclusion clear and consistent with the intended pathway.

How GRZAN can help. GRZAN provides medical device and IVD registration, quality system, Korean licence holder and local testing support for the Republic of Korea. Our team prepares MFDS-compliant technical dossiers, coordinates KGMP documentation, and supports post-market vigilance obligations. Business enquiries: info@grzanglobal.com