Clinical Equivalence Under EU MDR: What the Criteria Actually Require

Claiming equivalence with another device is one of the most common routes manufacturers use to support a clinical evaluation without conducting a clinical investigation. Under MDD, this was relatively manageable — the bar was lower, the criteria were loosely interpreted, and Notified Bodies had some flexibility in what they accepted. Under MDR, that flexibility largely disappeared. MDCG 2020-6 sets out the equivalence criteria in detail, and the guidance is read strictly.

The three criteria — and what they mean in practice

MDR Annex XIV Part A requires that for devices to be considered equivalent, they must be similar in all three of the following respects:

Clinical: same intended purpose, same medical indications, same part of the body, same user population, same contraindications. The word "similar" does not mean "overlapping" — it means closely comparable. A device used in the same anatomical region but for a different clinical indication does not satisfy this.

Technical: same design, same conditions of use, same specifications and properties — including relevant physicochemical properties and the principles of operation. Differences in dimensions, surface treatments, coatings, or delivery mechanisms can all be disqualifying, depending on whether they affect clinical performance or safety.

Biological: same materials in contact with tissues or body fluids. This is the one that most often gets overlooked at the scoping stage. Two devices can be clinically and technically similar but fail equivalence if one uses a silicone contact surface and the other uses a polyurethane one — unless you can demonstrate that the difference is not clinically significant.

The key rule: all three criteria must be met. You cannot satisfy two of the three and claim partial equivalence. The standard is conjunction, not balance.

The access problem for competitor devices

This is the change that had the biggest practical impact: if you want to use clinical data from a device you don't manufacture, you need documented access to that device's technical documentation. For devices from your own product family — a predecessor model, a variant you still sell — this is usually straightforward. For a competitor's device, it's almost never possible.

There is a narrow route: you can enter into a contractual arrangement with the other manufacturer granting you access to their technical file. In practice this is rare, because manufacturers have no commercial incentive to open their technical documentation to competitors. The result is that many manufacturers who relied on competitor equivalence under MDD have had to either build their own clinical data or find an equivalent device within their own portfolio.

MDR vs MDD — the key differences

Under MDD, equivalent devices were often identified through published literature and general device knowledge. The technical and biological criteria existed but were applied with more latitude. It was common to see CERs citing a single predicate device description from a paper, asserting similarity, and moving on.

Under MDR, MDCG 2020-6 requires the equivalence demonstration to be:

• Explicitly documented, attribute by attribute
• Supported by evidence, not assertion
• Accompanied by a clear rationale for why any differences do not affect safety or clinical performance

The shift is from declaration to demonstration. If your CER has an equivalence section that reads like a statement of similarity rather than a structured comparison with evidence, it will not hold up under MDR review.

When equivalence doesn't work

If you cannot meet the three criteria or cannot access the technical documentation for the comparator device, equivalence is not available as a route. Your options then are:

• Build a clinical evaluation based on your own device's performance data (post-market surveillance data, complaints, vigilance, published studies involving your device)
• Commission a clinical investigation under Article 62 or use existing investigation data
• For lower-risk devices with sufficient post-market data, the data from PMS and literature about the underlying technology may be sufficient without equivalence

One thing worth noting: "no equivalent device exists" is not automatically a problem — it means your CER needs to rely on a different data strategy. The CER still needs to demonstrate safety and performance; it just does so through a different evidence path.

MDCG 2020-6 as a practical checklist

If you are building or reviewing an equivalence claim, MDCG 2020-6 is the reference document your Notified Body will use. Work through the clinical, technical, and biological criteria as the guidance defines them — not as you interpret them. The guidance includes worked examples and lists of attributes to compare. Treating it as a checklist before your CER is written saves significant rework later.