Article 61(4): Why Your Clinical Investigation Exemption May Fail

Written by HATEM RABEH, MD, MSc Ing

Your Clinical Evaluation Expert And Partner

in
S

I review clinical evaluation reports weekly where manufacturers assume their equivalence claim automatically exempts them from clinical investigations under Article 61(4). The assumption feels logical. They demonstrated equivalence according to MDCG 2020-5. They followed the clinical evaluation process. Why would they need to conduct a clinical investigation?

The reality is more layered. Article 61(4) does not simply say “equivalence equals exemption.” The provision establishes a conditional framework that many manufacturers interpret too broadly. MDCG 2023-7 clarifies this framework, but the guidance reveals how narrow the exemption actually is.

Understanding the Article 61(4) pathway requires looking at what the exemption actually exempts you from, under what conditions, and what remains required even when the exemption applies.

What Article 61(4) Actually States

Article 61(4) of MDR 2017/745 allows manufacturers to avoid conducting new clinical investigations for their device if specific conditions are met. The core requirement centers on demonstrating equivalence to another device already on the market with sufficient clinical data.

The provision reads clearly: the manufacturer must demonstrate that the device “is equivalent to a device already marketed” and that equivalence is based on clinical, technical, and biological characteristics. The clinical data from the equivalent device, combined with non-clinical data, must be sufficient to demonstrate conformity.

Most manufacturers stop reading there. They focus on establishing equivalence and assume that completes the Article 61(4) requirement.

What they miss is the qualifying language throughout the article. Equivalence alone does not trigger the exemption. The equivalence must enable you to rely on clinical data from the equivalent device. That clinical data must be sufficient to demonstrate conformity to the applicable General Safety and Performance Requirements.

This distinction matters because your clinical evaluation must still demonstrate conformity. Equivalence is the tool. Conformity demonstration is the requirement. If the available clinical data from the equivalent device cannot support conformity demonstration, Article 61(4) does not apply.

The Three Pillars MDCG 2023-7 Clarifies

MDCG 2023-7 structures the Article 61(4) assessment around three core elements that must all be satisfied. Miss one element, and the exemption collapses.

Pillar One: Valid Equivalence Demonstration

Equivalence must be demonstrated according to the requirements in MDCG 2020-5. This means technical, biological, and clinical equivalence at a level that allows you to transfer clinical conclusions from the equivalent device to your device.

Many manufacturers confuse similarity with equivalence. They identify a device with comparable intended use and assume equivalence can be claimed. MDCG 2020-5 requires detailed comparison across design, materials, specifications, performance, and clinical outcomes.

The equivalence must be so close that differences do not affect clinical safety and performance. Small technical variations that seem insignificant can invalidate equivalence if those variations could influence clinical outcomes.

In one audit, a manufacturer claimed equivalence to a predicate catheter. The technical comparison showed identical materials and dimensions. The clinical comparison referenced clinical data from the predicate. Everything looked aligned.

The deficiency came from the delivery system. The subject device used a different introducer mechanism. The manufacturer considered this a minor variation unrelated to the catheter itself. The Notified Body disagreed. The introducer mechanism directly affects procedural success rates, user error potential, and complication profiles. The clinical data from the predicate could not be transferred because the clinical use scenario differed.

Equivalence collapsed, and Article 61(4) no longer applied.

Pillar Two: Access to Clinical Data from the Equivalent Device

Equivalence means nothing if you cannot access the clinical data from the equivalent device. Article 61(4) assumes you can rely on that data. That requires either owning the data yourself or obtaining a contract with the manufacturer of the equivalent device granting you access.

This is where many Article 61(4) pathways fail before they start. Manufacturers identify a marketed predicate device, demonstrate equivalence, and then realize they have no legal access to the underlying clinical data.

Literature data is not sufficient for this pillar. Published studies provide some clinical evidence, but Article 61(4) relies on the full clinical evaluation of the equivalent device, including PMCF data, complaints, vigilance reports, and ongoing safety monitoring. You need access to the complete clinical dataset, not just what appears in journals.

Without a formal data access agreement, your equivalence demonstration cannot support Article 61(4). You demonstrated equivalence to a device whose data you cannot use. The exemption does not apply.

I see this often with legacy devices. A manufacturer wants to claim equivalence to their own older device from before MDR. They assume internal equivalence solves the problem. But if the legacy device does not have a complete clinical evaluation under MDR standards, the data available may not be sufficient even though it is their own device.

Pillar Three: Clinical Data Sufficiency for Conformity Demonstration

This is the pillar most manufacturers underestimate. Even with valid equivalence and full data access, Article 61(4) only applies if the available clinical data is sufficient to demonstrate conformity to all applicable General Safety and Performance Requirements.

Sufficiency is not assumed. MDCG 2023-7 emphasizes that the clinical evaluation must actively assess whether the clinical data from the equivalent device addresses all safety and performance claims for your device.

Clinical data sufficiency depends on your device classification, intended use, novelty of claims, patient population, and risk profile. High-risk devices require more robust clinical evidence. Devices making performance claims beyond the equivalent device require additional data supporting those claims.

In one review, a manufacturer claimed equivalence to a surgical mesh for hernia repair. The equivalence demonstration was solid. The data access agreement was in place. The clinical data from the equivalent device included a five-year PMCF study with over two thousand patients.

The deficiency came from the performance claims. The subject device claimed reduced recurrence rates compared to standard mesh based on design modifications. The equivalent device made no such claim. The clinical data from the equivalent device could not support a claim the equivalent device never made.

The manufacturer needed additional clinical data demonstrating the claimed performance benefit. Article 61(4) could support the safety demonstration but not the performance claim differentiation. A clinical investigation became necessary.

What MDCG 2023-7 Adds to the Assessment

MDCG 2023-7 does not change Article 61(4), but it structures how Notified Bodies and manufacturers should assess whether the exemption applies. The guidance establishes a decision tree that forces systematic evaluation of each condition.

The guidance emphasizes that Article 61(4) is an exception, not the default pathway. The default assumption under MDR is that clinical investigations are required unless the manufacturer can demonstrate that existing clinical data is sufficient.

This shifts the burden. You must actively prove sufficiency. You cannot assume sufficiency based on device type, predicate history, or standard of care. The clinical evaluation must explicitly address why additional clinical investigations are not necessary.

MDCG 2023-7 also clarifies that Article 61(4) applies to the clinical investigation requirement, not to the clinical evaluation requirement. Manufacturers sometimes confuse these. Article 61(4) does not exempt you from conducting a clinical evaluation. It exempts you from conducting a clinical investigation as part of that clinical evaluation, provided the existing data is sufficient.

You still need a complete clinical evaluation report. You still need appraisal of all available clinical data. You still need a PMCF plan. Article 61(4) only removes the requirement to generate new clinical data through a prospective investigation.

Where Article 61(4) Fails in Practice

Most Article 61(4) failures come from one of three scenarios.

First, manufacturers claim equivalence based on intended use similarity rather than detailed technical and clinical comparison. They identify a device in the same clinical space and assume equivalence can be established. When the Notified Body requests the detailed equivalence dossier, the comparison reveals differences that break equivalence.

Second, manufacturers demonstrate valid equivalence but lack access to sufficient clinical data. They rely on published literature, which provides some evidence but not the complete clinical dataset required to support conformity demonstration. The equivalence is real, but unusable for Article 61(4) purposes.

Third, manufacturers underestimate the data requirements for their specific device. They assume that because similar devices exist with clinical data, their device automatically qualifies. They do not account for risk class, novelty, performance claims, or patient population differences that increase the evidence threshold.

In practice, Article 61(4) works best for devices with minimal modifications to well-established predicates where the manufacturer controls both devices and has complete clinical datasets. The further you move from that scenario, the harder Article 61(4) becomes to justify.

How Notified Bodies Review Article 61(4) Claims

Notified Bodies approach Article 61(4) claims with skepticism, not because they want to create barriers, but because they see many claims that do not meet the requirements. They know that manufacturers often misinterpret the scope of the exemption.

The Notified Body review typically follows the MDCG 2023-7 structure. They verify equivalence first. If equivalence is not demonstrated rigorously, the review stops there. No equivalence means no Article 61(4), regardless of data availability.

If equivalence is valid, they assess data access. They request the data sharing agreement or internal documentation proving you control the data. If you cite a predicate device but cannot prove data access, the review stops.

If equivalence and data access are confirmed, the review focuses on sufficiency. The Notified Body reviews your clinical evaluation report to determine whether the available clinical data addresses all General Safety and Performance Requirements, all risk mitigations, all performance claims, and all use conditions.

They look for gaps. Any requirement not fully supported by the available clinical data creates a deficiency. The deficiency often requests either additional data or a clinical investigation plan.

This is why the clinical evaluation quality determines Article 61(4) success. A weak clinical evaluation cannot demonstrate sufficiency, even if the underlying data exists. The appraisal must be thorough, the gaps must be identified, and the justification for sufficiency must be explicit.

What You Must Still Do Even Under Article 61(4)

Article 61(4) exempts you from conducting a clinical investigation. It does not exempt you from anything else.

You still need a complete clinical evaluation according to MDR Annex XIV and MDCG 2020-6. That means Stage 0 planning, Stage 1 identification of all available data, Stage 2 appraisal of that data, Stage 3 analysis for conformity demonstration, and Stage 4 conclusions including the PMCF plan.

You still need a PMCF plan. Article 61(4) does not eliminate post-market clinical follow-up. In fact, relying on equivalence without generating your own pre-market clinical data increases the importance of PMCF. You must monitor your device in real use to confirm that the equivalence-based predictions hold true.

You still need ongoing safety monitoring, vigilance, trend analysis, and periodic safety update reports. Article 61(4) affects pre-market data generation, not post-market obligations.

You still need to justify why a clinical investigation is not necessary. That justification must appear explicitly in the clinical evaluation report with clear reasoning tied to the available evidence.

The workload for Article 61(4) is not dramatically lighter than conducting a clinical investigation. The work shifts from designing and running a study to rigorously demonstrating equivalence, accessing comprehensive data, and proving sufficiency. Both pathways require substantial effort and documentation.

When Article 61(4) Is the Wrong Path

Some devices should not pursue Article 61(4) even if equivalence seems possible.

If your device introduces technical innovations that could affect safety or performance, Article 61(4) becomes difficult to justify. Innovations mean differences, and differences challenge equivalence. Trying to force equivalence when your device is intentionally different usually fails.

If your device targets a different patient population than the equivalent device, sufficiency becomes hard to demonstrate. Clinical outcomes can vary across populations. Data from one population may not transfer to another, even with technical equivalence.

If your device makes performance claims that differentiate it from competitors, Article 61(4) may not cover those claims. You can potentially use equivalence for safety demonstration but need additional data for performance differentiation.

If you are entering a therapeutic area where clinical data expectations are high and state of the art is advancing rapidly, relying on older predicate data may not meet current standards. SOTA evolves, and data sufficiency requirements evolve with it.

In these scenarios, planning for a clinical investigation from the start saves time compared to attempting Article 61(4), facing deficiencies, and then designing a study under time pressure.

Moving Forward with Article 61(4)

Article 61(4) is a legitimate pathway when the conditions genuinely exist. It is not a shortcut, but it can be appropriate for certain devices.

The key is honest assessment early in development. Can you demonstrate equivalence at the level MDCG 2020-5 requires? Do you have full access to the clinical data from the equivalent device? Is that data sufficient to address all aspects of your conformity demonstration?

If the answer to any question is uncertain, plan for a clinical investigation. Uncertainty in Article 61(4) eligibility almost always resolves as ineligibility during Notified Body review.

If you proceed with Article 61(4), treat the clinical evaluation as the core deliverable. The quality of your equivalence demonstration and sufficiency justification determines whether the Notified Body accepts your approach. MDCG 2023-7 provides the framework. Your clinical evaluation must follow that framework rigorously.

The final question is not whether you can claim Article 61(4). The question is whether your clinical evaluation can demonstrate that no additional clinical investigation is necessary to prove your device is safe and performs as intended. Answer that question with evidence, and Article 61(4) becomes defensible.

Peace,
Hatem
Clinical Evaluation Expert for Medical Devices
Follow me for more insights and practical advice.