Why Equivalence Claims Fail for Class III and Implantable Devices

Written by HATEM RABEH, MD, MSc Ing

Your Clinical Evaluation Expert And Partner

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This scenario repeats itself more often than it should. Manufacturers with Class III or implantable devices look at the equivalence pathway and see an opportunity to avoid costly clinical investigations. What they miss is that equivalence under MDR is not a shortcut. For high-risk devices, it is a narrow corridor with strict conditions that most products cannot meet.

The reality is simple: equivalence is possible for Class III and implantable devices under MDR, but it is rare. And when manufacturers try to force it, the consequences are not just a rejected clinical evaluation report. It is delayed market access, disrupted timelines, and a need to redesign the entire clinical strategy mid-process.

What MDR Actually Says About Equivalence

MDR Article 61(5) sets out the conditions for equivalence. The device must be technically, biologically, and clinically similar to the equivalent device. The equivalent device must have sufficient clinical evidence. The manufacturer must have full access to the technical documentation of the equivalent device. And the equivalent device must remain compliant with the essential requirements under MDR.

On paper, these conditions apply to all device classes. But in practice, the threshold for demonstrating equivalence becomes exponentially higher as risk increases. For Class III and implantable devices, the regulatory expectation is not just similarity. It is near-identity.

MDCG 2020-5 on clinical evaluation clarifies this further. It states that equivalence claims must be supported by a detailed comparative analysis. This includes materials, design features, clinical performance, and intended purpose. The guidance explicitly warns that equivalence is rarely acceptable for high-risk devices unless the comparison is exhaustive and the evidence robust.

Why Equivalence Claims Fail in Practice

Most equivalence claims fail because manufacturers underestimate what the Notified Body will scrutinize. They assume that if the devices look similar and share an intended purpose, equivalence can be justified. That assumption collapses when the reviewer starts digging into technical details.

Let me give you a real example. A manufacturer submitted a Class III active implantable cardiac device and claimed equivalence to a predicate from a competitor. The two devices had the same indication, similar specifications, and comparable clinical data in the literature. On the surface, the claim looked reasonable.

The Notified Body rejected it. Why? The materials in contact with tissue were different. The power source design was different. The implantation technique was different. And the manufacturer could not access the full technical documentation of the predicate because it belonged to a competitor. Without that access, there was no way to demonstrate biological and technical equivalence at the level required by MDR.

This is the pattern I see repeatedly. Equivalence claims that rely on publicly available data or superficial comparisons do not survive scrutiny. The reviewer will ask for raw data from the equivalent device. They will ask for biocompatibility testing under identical conditions. They will ask for proof that failure modes and degradation pathways are the same. If you cannot provide that, the claim collapses.

The Three Conditions That Break Equivalence Claims

There are three conditions that consistently cause equivalence claims to fail for Class III and implantable devices. These are not edge cases. They are the most common reasons I see in audit findings and Notified Body queries.

First: Lack of Access to Technical Documentation

If the equivalent device is manufactured by another company, you need their full cooperation to access design files, risk analysis, biocompatibility data, and manufacturing process documentation. Most competitors will not provide this. Even within the same corporate group, access can be difficult if the devices were developed independently.

Without this documentation, you cannot perform the detailed comparative analysis required by MDR. You are left with publicly available data, which is never sufficient for high-risk devices. The Notified Body will issue a non-conformity, and you will have no way to close it without conducting your own clinical investigation.

Second: Material or Design Differences

Class III and implantable devices interact with the body in complex ways. Even small differences in materials, coatings, or structural design can affect biological response, performance, and safety. Equivalence requires you to prove that these differences have no clinical impact. That proof must come from testing, not assumptions.

I have seen equivalence claims fail because the subject device used a different polymer formulation in a critical component. The manufacturer argued that both polymers were biocompatible. The Notified Body asked for comparative biocompatibility testing under identical conditions. The manufacturer did not have it. The claim was rejected.

Third: Insufficient Clinical Data for the Equivalent Device

Even if you have access to technical documentation and the devices are technically similar, equivalence still requires that the equivalent device itself has sufficient clinical evidence under MDR standards. If the equivalent device was CE marked under the old directives but has not yet undergone MDR-level clinical evaluation, it cannot serve as a valid equivalent.

This catches many manufacturers off guard. They assume that because the equivalent device is already on the market, its clinical evidence is automatically sufficient. That is not how MDR works. The evidence must meet current standards, not legacy standards. If it does not, the equivalence claim fails.

When Equivalence Might Actually Work

Equivalence is not impossible for Class III and implantable devices. But the circumstances where it works are narrow. In my experience, it works in three scenarios.

First: when both devices are manufactured by the same company and are part of the same product family. This gives you full access to technical documentation, shared design history, and comparable clinical data. Even here, you must document every difference and justify why it does not affect clinical performance.

Second: when the subject device is a minor modification of an already-certified device. For example, a different size variant with identical materials, design principles, and clinical indications. The modification must be minor enough that it does not introduce new risks or change the clinical profile.

Third: when equivalence is used to support part of the clinical evaluation, not the entire strategy. You may claim equivalence for certain aspects of performance while supplementing with additional clinical data for other aspects. This hybrid approach is more defensible than relying entirely on equivalence.

Outside these scenarios, equivalence for Class III and implantable devices is almost always a trap. It looks faster at the beginning. It becomes slower and more expensive when the Notified Body rejects it and you have to start over.

What to Do If You Cannot Claim Equivalence

If equivalence is not viable, the alternative is a clinical investigation. For Class III and implantable devices, this is not just acceptable. It is often the only credible path under MDR.

A well-designed clinical investigation generates direct evidence for your device under controlled conditions. It avoids the complications of comparative analysis, access to third-party documentation, and dependency on legacy data. And it positions your clinical evaluation report as robust and defensible from the start.

Yes, clinical investigations take time and resources. But forcing an equivalence claim that will not survive review wastes more time and more resources. I have seen manufacturers lose two years trying to salvage a failed equivalence strategy. By the time they pivoted to a clinical investigation, they had burned budget, missed timelines, and damaged relationships with their Notified Body.

How Notified Bodies Evaluate Equivalence for High-Risk Devices

Understanding how Notified Bodies review equivalence claims can help you avoid predictable failures. The review is not subjective. It follows a structured logic that you can anticipate.

The reviewer starts by assessing whether the equivalent device itself has sufficient clinical evidence. If it does not, the claim stops there. If it does, the reviewer moves to the comparative analysis. They will check whether you have access to the full technical documentation of the equivalent device. If you do not, the claim stops again.

If you pass those two gates, the reviewer will scrutinize the comparison. They will look for differences in materials, design features, manufacturing processes, and clinical performance. For each difference, they will ask whether you have tested its clinical impact. Theoretical arguments are not enough. You need data.

Finally, the reviewer will assess whether the clinical evidence for the equivalent device is applicable to your device. If the populations, indications, or clinical endpoints differ, the evidence may not transfer. And if the equivalent device has known safety concerns or performance limitations, those concerns now extend to your device as well.

This is why I tell manufacturers to map out the entire equivalence argument before committing to it. Walk through the review logic. Identify where the gaps are. If you cannot close those gaps with existing data, equivalence is not a viable path.

Final Considerations

Equivalence for Class III and implantable devices is not a regulatory loophole. It is a legitimate pathway when the conditions are met. But those conditions are strict, and the evidence required is extensive. Most manufacturers overestimate how much similarity is enough and underestimate how much documentation is needed.

If you are considering equivalence, start by asking whether you have full access to the technical and clinical documentation of the equivalent device. If the answer is no, stop. You will not be able to defend the claim.

If the answer is yes, move to the comparative analysis. Document every difference, no matter how small. Test the clinical impact of those differences. And ensure that the equivalent device has clinical evidence that meets MDR standards, not legacy standards.

If at any point this process becomes uncertain, pivot to a clinical investigation. It is the safer, more predictable, and often faster route for high-risk devices.

Because in the end, the goal is not to find the easiest path to market. It is to build a clinical evaluation that survives review, supports patient safety, and withstands regulatory scrutiny over the lifetime of your device.

Peace,
Hatem
Clinical Evaluation Expert for Medical Devices
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