---
title: When You Cannot Claim Equivalence: Generating Your Own Clinical Data
description: If equivalence fails, you have to generate your own clinical data. Here is how to recognise that moment and plan the investigation that follows.
authors: Tibor Zechmeister, Felix Lenhard
category: Clinical Evaluation & Investigations
primary_keyword: cannot claim equivalence MDR
canonical_url: https://zechmeister-solutions.com/en/blog/cannot-claim-equivalence-generate-data
source: zechmeister-solutions.com
license: All rights reserved. Content may be cited with attribution and a link to the canonical URL.
---

# When You Cannot Claim Equivalence: Generating Your Own Clinical Data

*By Tibor Zechmeister (EU MDR Expert, Notified Body Lead Auditor) and Felix Lenhard.*

> **You cannot claim equivalence under MDR when any of the three characteristic groups in Annex XIV Part A Section 3 — technical, biological, or clinical — fails to hold, when the predicate is a competitor's device and your device is implantable or Class III and you do not have an ongoing contract giving sufficient levels of access to the predicate's technical documentation under Article 61(5), or when the available literature and post-market data cannot close the gap. The moment one of these conditions is confirmed, you stop defending equivalence and start planning to generate your own clinical data — which, for most novel Class III and implantable devices, means a clinical investigation designed under Article 62, Annex XV, and EN ISO 14155:2020+A11:2024. Recognising that moment early is the single most important cost and timeline decision in the clinical evaluation.**

**By Tibor Zechmeister and Felix Lenhard. Last updated 10 April 2026.**

---

## TL;DR

- Equivalence under MDR fails when any of the three pillars in Annex XIV Part A Section 3 — technical, biological, or clinical — does not hold at the MDCG 2020-5 level of detail.
- For implantable and Class III devices, Article 61(5) additionally requires a contract with the predicate manufacturer giving ongoing sufficient levels of access to the technical documentation. MDCG 2023-7 (December 2023) defines what that access means in practice.
- Literature and post-market clinical follow-up data can sometimes close a narrow gap, but neither is a substitute for equivalence when the pillars genuinely do not hold.
- When equivalence is not possible, Article 61 and Annex XIV require the results of a clinical investigation — and for implantable and Class III devices under Article 61(4), this is the default path that must be planned from the start.
- Recognising the failure of equivalence months before the CER is written is the difference between a controlled investigation on the original timeline and a rushed investigation that breaks the project.

---

## The moment equivalence stops being the plan

There is a moment in almost every MDR project where the team has to decide whether equivalence is real or whether it has become a story the team is telling itself to avoid a clinical investigation. The moment usually arrives quietly. A biological characteristic that was "close enough" in the first draft of the equivalence table turns out to be not quite the same polymer grade. A clinical characteristic that was "the same condition" turns out to apply to a slightly different population. A contract with the predicate manufacturer that was "being discussed" turns out to have been politely declined six weeks ago.

When these moments stack up, the team has two choices. Defend a weaker and weaker equivalence argument all the way to the Notified Body, discover the rejection at the worst possible time, and then start a clinical investigation on a broken timeline. Or recognise early — honestly, coldly — that equivalence is no longer the plan, and use the remaining runway to plan and run the clinical investigation properly.

This post is for the second path. We walked through the positive case in [post 120, Equivalence Under MDR](/blog/equivalence-under-mdr). This one covers the failure modes, the diagnostic moment, and the transition from "we are claiming equivalence" to "we are generating our own data."

## The three pillars failing

Equivalence under MDR lives or dies on the three characteristic groups in Annex XIV Part A Section 3: technical, biological, and clinical. MDCG 2020-5 (April 2020) treats the three as independent. A strong argument on two of them does not compensate for a weak argument on the third. If one pillar genuinely fails, equivalence fails.

**Technical failure.** The design, specifications, principles of operation, or critical performance of the subject device differ from the predicate in a way that affects safety or performance and cannot be justified with evidence. A different sterilisation method that changes the material behaviour. A different deployment mechanism that changes the force profile. A different software architecture that changes the decision path. Each of these can be enough. Under MDCG 2020-5 the burden is on the manufacturer to prove that every difference is clinically insignificant with evidence, not to assert it.

**Biological failure.** The materials in contact with the patient are not the same, or the contact site, duration, or release characteristics differ. For implantable devices and devices with long-term tissue contact, this pillar is the one that most often takes the argument down. It is hard to prove biological equivalence to a competitor's device without knowing the exact composition and processing of the competitor's material — and the exact composition and processing are exactly what a competitor will not share.

**Clinical failure.** The condition, target population, site in the body, severity, user profile, or clinical performance claims differ. A device used for the same indication but in paediatrics where the predicate was adults. A device used at a different anatomical site. A device whose clinical performance claim is stronger than anything the predicate's data supports. Any of these ends the clinical pillar.

The diagnostic move is to run the three pillars as a structured, tabular MDCG 2020-5 comparison early — before the CER is drafted — and to read the result honestly. If one pillar cannot be closed, equivalence is over.

## The "sufficient levels of access" gap for implantable and Class III devices

For implantable devices and Class III devices, the three pillars are only half the problem. Article 61(5) of Regulation (EU) 2017/745 sets the second bar, and for most startups it is the harder one.

Article 61(5) allows equivalence across manufacturers for implantable and Class III devices only where the manufacturer making the claim has a contract in place that gives ongoing sufficient levels of access to the predicate's technical documentation. Article 61(6) governs the general principle that where a clinical investigation is not performed pursuant to 61(4), the non-performance must be justified in the clinical evaluation. MDCG 2023-7 (December 2023) is the authoritative guidance on what "sufficient levels of access to data" means in practice and on the four cases in which implantable and Class III devices may be exempted from the mandatory pre-market clinical investigation of Article 61(4).

The practical reading is unforgiving. Sufficient levels of access is not public information, not a literature search, not a one-off data purchase, not an NDA signed after a conference conversation. It is an ongoing contractual relationship that gives the subject device manufacturer access to the full technical documentation of the predicate over time. Competitors do not grant this. Almost never. The only cases where this route works cleanly are equivalence to an earlier device in the same manufacturer's portfolio, where the access is automatic because the manufacturer owns both sides of the relationship.

For a startup building a novel Class III or implantable device, the honest reading of Article 61(5) and MDCG 2023-7 is that equivalence to a competitor's device is almost never realistic. The moment the team confirms that the target predicate is a competitor's device and no contract is available, the equivalence route for that predicate is closed — not because the three pillars fail but because the access bar is insurmountable. Recognising this on day one saves months that would otherwise be spent trying to negotiate access that is not coming.

## When literature is not enough

The first instinct after equivalence fails is often to ask whether literature can close the gap instead. Sometimes it can. Often it cannot, and the distinction matters.

Literature can support a clinical evaluation when the scientific claim is general enough that published studies on the technology, the measurement method, the condition, or the standard-of-care cover the specific claim in the intended purpose. Established measurement methods used in new combinations — the Graz pattern we described in [post 132, What Is a Clinical Investigation Under MDR](/blog/what-is-clinical-investigation-mdr) — are a legitimate example. Literature on the underlying pharmacology of a well-characterised excipient is another.

Literature is not enough when the clinical claim is specific to the subject device in a way no published study addresses. A novel mechanism of action, a novel combination of features that changes the safety profile, a novel indication, a novel population — none of these can be carried by literature on adjacent devices. A reviewer at the Notified Body or the competent authority reads the CER asking a simple question: does this published work actually tell us what this specific device does in this specific intended use? If the answer is no, the literature is context, not evidence, and the clinical evaluation still has a gap.

The test a manufacturer should apply is the same adversarial test that applies to equivalence. Would you accept the literature argument if you were the reviewer looking for reasons to reject it? If the answer is no, literature has not closed the gap, and the project needs new data.

## When PMCF cannot fill the gap

Post-market clinical follow-up (PMCF) data — data collected on the device after it is placed on the market — is sometimes offered as the alternative to a pre-market clinical investigation. For legacy devices transitioning into the MDR with real post-market evidence, this can be part of the answer. For a novel device that is not yet on the market, it is not an answer at all.

Two reasons. First, PMCF is by definition post-market. For a pre-market conformity assessment of a novel device, PMCF data on that specific device does not yet exist. Second, even where PMCF-style data exists on similar-but-not-equivalent devices, MDCG 2020-5 is explicit that similar-device data can inform risk analysis and context but does not constitute clinical evidence for the subject device. The distinction is deliberate.

There is a narrower case where PMCF planning — the commitment to generate specific post-market evidence after certification — can support a reduced pre-market data package, typically for devices where the risk profile and the state of the art permit it. This is a conversation with the Notified Body, not a unilateral manufacturer decision, and it does not apply to the case where a novel implantable or Class III device has no defensible equivalence argument and no existing clinical data. In that case, pre-market clinical investigation is the route the Regulation expects.

## Planning a clinical investigation as the only remaining option

Once equivalence has been honestly retired and literature and PMCF cannot close the gap, the remaining option is to generate your own clinical data. For most novel implantable and Class III devices, and for novel lower-class devices where the scientific question cannot be answered any other way, this means a clinical investigation designed under MDR Article 62, Annex XV, and the harmonised Good Clinical Practice standard EN ISO 14155:2020+A11:2024.

The transition from "we were claiming equivalence" to "we are running an investigation" is not a small project change. It changes the scope of the CER, the timeline of the conformity assessment, the budget line for clinical operations, the competence requirements of the team, and the risk profile of the project. It also changes the regulatory obligations in a concrete way: sponsor obligations under Article 72, ethics committee approval in each member state where the investigation runs, competent authority application under the Article 70 framework, adverse event reporting under Article 80, end-of-investigation reporting under Article 77, and traceable compliance with Annex XV and EN ISO 14155:2020+A11:2024 throughout.

The practical sequence — compressed to its essentials — is the one we lay out in detail in [post 134, How to Plan a Clinical Investigation for MDR](/blog/how-to-plan-clinical-investigation-mdr) and [post 135, Designing the Clinical Investigation Plan](/blog/designing-clinical-investigation-plan). First, write down the single scientific question the investigation has to answer, on one line, without hedging — the question maps directly to the intended purpose and the specific clinical claim the equivalence argument failed to carry. Second, design the minimum viable study that answers that question defensibly: the smallest population, the cleanest endpoint, the tightest inclusion and exclusion criteria. Third, draft the clinical investigation plan under Annex XV and EN ISO 14155:2020+A11:2024 with a competent clinical lead, not with a borrowed template. Fourth, line up ethics committee and competent authority submissions in the member states where the investigation will run, acknowledging that the national procedures differ and the timelines are non-trivial. Fifth, set up the sponsor capability — monitoring, data management, pharmacovigilance-equivalent reporting for adverse events — either internally or through a contract research organisation, while making sure the sponsor accountability stays with the manufacturer under Article 72. Sixth, run the investigation, generate the data, and fold the results back into the clinical evaluation report as the primary clinical evidence.

None of this is optional, none of it scales down because the company is small, and none of it can be skipped by running an informal "pre-study" on a handful of patients. Any systematic use of the device on human subjects for the purpose of generating safety or performance data is a clinical investigation under Article 2(45) and triggers the full framework.

## The Subtract to Ship angle

Recognising that equivalence has failed is one of the hardest subtractions in MDR work, and one of the most valuable. The Subtract to Ship discipline (see [post 065, The Subtract to Ship Framework for MDR](/blog/subtract-to-ship-framework-mdr)) is usually described as cutting work that does not trace to a specific MDR obligation. The equivalence-to-investigation transition is the opposite move inside the same discipline: cutting the work that was trying to avoid a required obligation and replacing it with the obligation done properly.

The temptation to keep defending a fragile equivalence claim is real. Every week of equivalence defence is a week the clinical investigation is not running. The sunk cost of a half-written equivalence table and an almost-signed non-disclosure agreement is psychologically heavy. The Subtract to Ship move is to treat the sunk cost as sunk, cut the equivalence work the moment it stops being defensible, and put the runway into the investigation the Regulation actually requires.

The cheaper pathway is not always the equivalence pathway. A targeted, minimum viable clinical investigation — designed cleanly, scoped tightly, started early — can be cheaper and faster than a fragile equivalence argument that collapses at the Notified Body. The Evidence Pass inside the Subtract to Ship framework evaluates literature, equivalence, and clinical investigation honestly against each other. When equivalence fails the honest evaluation, the investigation is the remaining subtraction — the work that earns its place by tracing directly to Article 61 and Annex XIV.

## Reality Check — Where do you stand?

1. Have you run the three-pillar MDCG 2020-5 comparison as a structured table for each candidate predicate, or are you still working from a narrative argument?
2. For each pillar, can you point to a specific criterion where the comparison genuinely holds, and to every criterion where it does not, with the differences listed and the justifications (or missing justifications) recorded?
3. If your device is implantable or Class III and your candidate predicate is a competitor's device, do you have an ongoing contract in place that gives sufficient levels of access to the predicate's technical documentation under Article 61(5) — or have you accepted that you do not?
4. Have you read MDCG 2023-7 and confirmed that none of the four exemption cases apply to your specific situation, rather than assuming one of them does?
5. If you are leaning on literature to close a gap, would an adversarial reviewer accept that the literature actually answers the clinical question specific to your device?
6. If you are planning to lean on PMCF, does the PMCF concept survive the fact that the device is not yet on the market and that similar-device data is not equivalent-device data?
7. If equivalence is genuinely no longer the plan, is the clinical investigation on your timeline early enough that it is not going to become the critical path that blocks CE marking?
8. Do you have a clinical lead with the competence to design a study under Annex XV and EN ISO 14155:2020+A11:2024, or is the plan being drafted by a team that has not run an investigation before?

## Frequently Asked Questions

**When exactly can I not claim equivalence under MDR?**
You cannot claim equivalence when any of the three characteristic groups in Annex XIV Part A Section 3 — technical, biological, or clinical — fails at the MDCG 2020-5 level of detail; when your device is implantable or Class III, the predicate is a competitor's device, and you do not have an ongoing contract giving sufficient levels of access to the predicate's technical documentation under Article 61(5) as clarified by MDCG 2023-7; or when differences between subject and predicate cannot be justified as clinically insignificant with evidence.

**Does failing equivalence always mean running a clinical investigation?**
Not always, but often. For non-implantable, non-Class III devices, literature and harmonised standards can sometimes cover the clinical claims without a new investigation, provided the evidence genuinely answers the questions the GSPRs pose for the specific intended purpose. For implantable and Class III devices, Article 61(4) establishes clinical investigations as the general rule, and where none of the four MDCG 2023-7 exemption cases apply, a pre-market clinical investigation is the expected path.

**What does "sufficient levels of access to data" mean under MDCG 2023-7?**
It means that the manufacturer making the equivalence claim has, through a contract with the predicate's manufacturer, ongoing full access to the technical documentation of the predicate. Public information, published literature, a one-off data purchase, or informal arrangements are not sufficient for implantable and Class III devices under Article 61(5). MDCG 2023-7 (December 2023) clarifies how this requirement operates in practice and is the reference point Notified Bodies apply when they assess the access argument.

**Can post-market clinical follow-up data replace a pre-market clinical investigation?**
Generally not for a novel device. PMCF is, by definition, data collected after the device is placed on the market, so it does not exist yet for a novel pre-market device. For legacy devices with genuine post-market data, post-market evidence can contribute to the clinical evaluation. For novel implantable and Class III devices without equivalence and without prior market history, pre-market clinical investigation under Article 62, Annex XV, and EN ISO 14155:2020+A11:2024 is the route the Regulation expects.

**How early should I recognise that equivalence has failed?**
As early as possible, and certainly before the clinical evaluation report is drafted. Running the MDCG 2020-5 three-pillar comparison as a structured table at the start of the clinical evaluation — with an adversarial reading — surfaces failures before they become sunk costs. A clinical investigation started six months into the project with a clear scope is a very different proposition from one started eighteen months in because the equivalence argument finally collapsed at the Notified Body.

**If I cannot claim equivalence, can I still use the predicate's data for anything?**
Yes, but not as clinical evidence for your device. MDCG 2020-5 distinguishes equivalence (where another device's data becomes your clinical evidence) from similar-device data (which can inform risk analysis, the state of the art, and the clinical context but does not constitute clinical evidence for your device). Similar-device data has a legitimate role in the clinical evaluation, but it does not carry the clinical claims on its own.

## Related reading

- [MDR Article 61 and clinical evidence requirements for startups](/blog/mdr-article-61-clinical-evidence-requirements-startups) — the Article 61 walkthrough that frames when equivalence is allowed and when a clinical investigation is required.
- [Equivalence Under MDR: Demonstrating a Predicate Device](/blog/equivalence-under-mdr) — the positive case for equivalence and the MDCG 2020-5 three-pillar demonstration.
- [The three pillars of equivalence — technical, biological, clinical](/blog/three-pillars-equivalence-technical-biological-clinical) — the pillar-by-pillar deep dive referenced throughout this post.
- [Why equivalence is harder under MDR than MDD](/blog/equivalence-harder-under-mdr-than-mdd) — the historical context for the transition from MEDDEV 2.7/1 rev 4 practice to MDCG 2020-5 practice.
- [Sufficient clinical evidence under MDR](/blog/sufficient-clinical-evidence-mdr) — the adjacent question the equivalence-or-investigation decision answers.
- [What Is a Clinical Investigation Under MDR?](/blog/what-is-clinical-investigation-mdr) — the definition of a clinical investigation and the framework of Article 62, Annex XV, and EN ISO 14155:2020+A11:2024.
- [How to Plan a Clinical Investigation for MDR](/blog/how-to-plan-clinical-investigation-mdr) — the operational sequence for setting up an investigation once equivalence is retired.
- [Designing the Clinical Investigation Plan](/blog/designing-clinical-investigation-plan) — the Annex XV and EN ISO 14155:2020+A11:2024 content requirements for the plan itself.
- [Sponsor obligations under MDR Articles 62 and 72](/blog/sponsor-obligations-mdr) — the sponsor role that transitions to the manufacturer when an investigation is run.
- [Ethics committee approval for clinical investigations](/blog/ethical-approval-clinical-investigations) — the member-state-level approval pathway.
- [The Subtract to Ship Framework for MDR Compliance](/blog/subtract-to-ship-framework-mdr) — the methodology behind the Evidence Pass that evaluates equivalence and clinical investigation against each other.

## Sources

1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Article 61 (clinical evaluation), Article 61(4) (clinical investigations for implantable and Class III devices), Article 61(5) (equivalence across manufacturers and sufficient access to technical documentation), Article 61(6) (justification for non-performance of clinical investigations), Annex XIV Part A Section 3 (demonstration of equivalence). Official Journal L 117, 5.5.2017.
2. MDCG 2020-5 — Clinical Evaluation — Equivalence: A guide for manufacturers and notified bodies, April 2020.
3. MDCG 2023-7 — Guidance on exemptions from the requirement to perform clinical investigations pursuant to Article 61(4)-(6) MDR and on 'sufficient levels of access' to data needed to justify claims of equivalence, December 2023.
4. EN ISO 14155:2020+A11:2024 — Clinical investigation of medical devices for human subjects — Good clinical practice.

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*This post is part of the Clinical Evaluation & Clinical Investigations series in the Subtract to Ship: MDR blog. Authored by Felix Lenhard and Tibor Zechmeister. The moment equivalence stops being the plan is one of the hardest calls in an MDR project — and one of the most expensive to get wrong. If you are in that moment now, Zechmeister Strategic Solutions works with founders on exactly the transition from a fragile equivalence argument to a clean clinical investigation plan, before the Notified Body makes the call for you.*

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*This post is part of the [Clinical Evaluation & Investigations](https://zechmeister-solutions.com/en/blog/category/clinical-evaluation) cluster in the [Subtract to Ship: MDR Blog](https://zechmeister-solutions.com/en/blog). For EU MDR certification consulting, see [zechmeister-solutions.com](https://zechmeister-solutions.com).*