Why Most Equivalence Claims Fail Before Review Even Starts

Written by HATEM RABEH, MD, MSc Ing

Your Clinical Evaluation Expert And Partner

in
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The assumption goes like this: if our device is similar enough to an approved device, we can use its clinical data. It sounds reasonable. It’s been done for years under the directives. But under MDR, this logic collapses at the first question from a Notified Body.

MDCG 2020-5 sets out the framework for demonstrating equivalence. What manufacturers often miss is that this document doesn’t provide shortcuts. It provides conditions. And those conditions are stricter than what most teams prepare for.

What Equivalence Actually Means Under MDR

Equivalence is defined in MDR Article 61(5) and Annex XIV Part A. The subject device and the equivalent device must be demonstrated to have the same clinical, biological, and technical characteristics. Or, where there are differences, those differences must be shown not to adversely affect clinical safety and performance.

This is not a matter of opinion. It’s not a checklist where you tick boxes for similar materials and functions. It’s a structured argument that must survive critical scrutiny.

The problem starts when teams believe that equivalence is determined by engineering judgment alone. I’ve seen files where the equivalence claim was based on internal design comparisons, without engagement from clinical affairs, without a line-by-line justification of why each difference doesn’t matter clinically.

Notified Bodies don’t accept engineering similarity as proof of clinical equivalence. They expect you to show that the differences do not introduce new risks, do not change the benefit-risk profile, and do not alter clinical performance in ways that would require independent clinical investigation.

The Three Pillars: Technical, Biological, Clinical

MDCG 2020-5 organizes equivalence into three categories. All three must be demonstrated. A strong technical equivalence claim does not compensate for weak biological or clinical justification.

Technical Characteristics

This includes design, materials, manufacturing process, specifications, and intended use. The comparison must be detailed. It’s not enough to say “both devices use stainless steel.” You need to specify the grade, the surface treatment, the dimensions, the mechanical properties.

I’ve reviewed equivalence tables where materials were listed as “metal” and “polymer.” That tells a reviewer nothing. It signals that the manufacturer hasn’t done the work.

Where there are differences, you must explain why those differences are not clinically significant. A difference in wall thickness might be acceptable if you can show that mechanical performance and patient interaction remain equivalent. But you must show it. You can’t assume it.

Biological Characteristics

This is where many claims break down. Two devices can look identical on paper, but if the sterilization method differs, if the packaging changes, if the shelf life is extended, the biological interaction may no longer be equivalent.

Biocompatibility cannot be assumed. Even when the materials are the same, differences in processing or surface finish can alter the biological response. If your equivalent device has ISO 10993 testing for one configuration and your subject device uses a different configuration, you need to justify why that data still applies.

What kills equivalence claims here is the phrase “considered equivalent.” Reviewers don’t accept consideration. They expect evidence.

Clinical Characteristics

This is the final test. Even if technical and biological equivalence are solid, clinical equivalence requires that the devices perform the same way in clinical use. This means the same indications, the same patient population, the same expected outcomes.

If your subject device is intended for a slightly broader population, or a longer duration of use, or a different anatomical site, clinical equivalence is compromised. You cannot rely on the equivalent device’s clinical data unless the clinical context is truly the same.

I’ve seen manufacturers try to claim equivalence for a device used in pediatric patients based on data from adults. That’s not equivalence. That’s extrapolation, and it requires additional justification that most files don’t provide.

When Equivalence Cannot Be Claimed

MDCG 2020-5 is clear about situations where equivalence cannot be used. These are not negotiable.

If the equivalent device has a history of serious incidents that could be related to the characteristics you’re claiming as equivalent, you cannot use that device as a basis. If the equivalent device doesn’t have sufficient clinical data itself, equivalence doesn’t solve your problem. You’re just linking to another gap.

If the differences between devices are in critical areas—such as the active component, the drug-eluting coating, the algorithm in a software-driven device—equivalence is not the right path. You need independent clinical evidence.

Some manufacturers push equivalence to its limits, trying to stretch the definition to avoid clinical investigations. Reviewers see this. And when they see it, the entire clinical evaluation is questioned.

How to Structure the Equivalence Demonstration

A valid equivalence demonstration is a structured document. It’s not a section in the clinical evaluation report. It’s a standalone justification that the CER references.

Start with a clear statement of the subject device and the equivalent device. Include commercial names, models, classifications, regulatory status. The equivalent device must be legally on the market under MDR or under the directives with a clear path to MDR compliance.

Then build the comparison table. For each characteristic—technical, biological, clinical—list the subject device property, the equivalent device property, and the justification for why any difference is acceptable.

This table is where most of the work happens. If you write “similar” in the justification column, you’ve failed. Every entry must explain the reasoning. If the dimensions differ by 10%, explain why that difference doesn’t affect the clinical outcome. Reference testing, literature, risk analysis.

Include supporting documents. Test reports, certificates, design specifications, risk management files. The equivalence demonstration must be traceable. A reviewer should be able to follow every claim back to objective evidence.

The Role of Clinical Data

Even with valid equivalence, you still need clinical data. Equivalence allows you to rely on the equivalent device’s clinical data, but that data must be sufficient to demonstrate safety and performance for your device.

This means you must appraise the clinical data of the equivalent device. You must show that it covers your intended use, your patient population, your claims. If the equivalent device has limited data, equivalence doesn’t solve the problem. You inherit the limitations.

And you must have a plan for post-market clinical follow-up. Equivalence doesn’t exempt you from PMCF. In fact, when you claim equivalence, PMCF becomes even more important because you’re relying on an assumption that must be continuously verified in real-world use.

What Notified Bodies Actually Check

When a Notified Body reviews an equivalence claim, they start with skepticism. That’s not hostility. It’s method. They’ve seen too many claims that don’t hold up.

They check whether the equivalent device is actually on the market. They check its regulatory status. If it’s only CE marked under the directives and hasn’t been transitioned, that weakens the claim.

They check the comparison table line by line. They look for vague language, unsupported statements, missing justifications. If they find one weak entry, they question the entire table.

They check whether the clinical data is sufficient. They verify that PMCF is planned. They look at whether the risk management file acknowledges the equivalence assumption and includes monitoring for differences that might emerge post-market.

What they don’t accept: “The devices are similar, therefore the data applies.” That’s not an argument. That’s a hope.

Why Equivalence Is Getting Harder

Under the directives, equivalence was more flexible. Many devices reached the market based on equivalence claims that would not survive under MDR.

MDCG 2020-5 raised the bar. The guidance is detailed, and Notified Bodies are applying it strictly. The transition from MDD/AIMDD to MDR means many legacy equivalent devices no longer have clear regulatory status. If your equivalent device hasn’t transitioned, your claim is vulnerable.

There’s also increasing scrutiny on whether equivalence is being used to avoid necessary clinical investigations. If your device has novel features, or addresses a new patient population, or uses a modified design, equivalence may not be appropriate even if it seems technically feasible.

The regulatory environment is pushing manufacturers toward device-specific clinical data. Equivalence remains valid, but only when it’s truly justified.

Practical Steps to Strengthen Your Equivalence Claim

Start early. Don’t wait until the clinical evaluation is being written to assess equivalence. It should be part of the development process.

Identify the equivalent device early and verify its regulatory status. Confirm that it has sufficient clinical data. If the data is weak, equivalence won’t save you.

Build the comparison table with input from regulatory, clinical, and technical teams. Equivalence is not a regulatory task alone. It requires clinical reasoning and technical depth.

Document every justification. When you say a difference is not clinically significant, reference risk analysis, testing, or literature. Make it traceable.

Plan your PMCF to monitor the equivalence assumption. If the differences you identified turn out to matter in real-world use, you need to detect that early.

And be ready to abandon equivalence if it doesn’t hold. If the claim is weak, forcing it through will cost more time and credibility than starting with an independent clinical investigation.

The Reality Check

Equivalence under MDR is not a workaround. It’s a rigorous pathway that requires structured justification, objective evidence, and ongoing verification.

Most manufacturers underestimate the documentation burden. They assume similarity is enough. It’s not. The question is not whether the devices look alike. The question is whether a clinician, a patient, or a regulator would expect the same outcomes. And that expectation must be defended.

If your equivalence claim can’t survive a critical question from a Notified Body, it’s not ready. And if it’s not ready, it will delay your submission, trigger major objections, or force you back to clinical investigation after months of wasted effort.

The guidance is clear. The pathway is defined. What’s missing in most cases is the discipline to apply it correctly.

Peace,
Hatem
Clinical Evaluation Expert for Medical Devices
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