Class I devices are not exempt from clinical evaluation. MDR Article 61 requires clinical evaluation for every device, at every class. What changes with Class I is the amount and type of evidence that is "sufficient" to demonstrate conformity with the relevant general safety and performance requirements. For most Class I devices, sufficient clinical evidence can be built from a structured literature review, equivalence to an existing device, or reliance on harmonised standards that cover the established measurement or technology — without a new clinical investigation. The obligation is real. The scale is proportionate. Getting the evidence hierarchy right is where Class I startups save months and hundreds of thousands of euros.

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

TL;DR

  • MDR Article 61(1) requires clinical evaluation for every medical device regardless of class. Class I is not exempt.
  • Article 61(10) recognises that for some devices, demonstration of conformity with the general safety and performance requirements based on clinical data is not deemed appropriate — in which case the manufacturer must justify, based on the risk management output, why non-clinical testing methods are adequate.
  • Article 61(11) makes clear that the clinical evaluation and its documentation must be proportionate to the nature, classification, intended purpose, and risks of the device.
  • The hierarchy of evidence sources for Class I: literature on the state of the art and on equivalent or similar devices, equivalence per MDCG 2020-5, compliance with harmonised standards covering established methods, and — only when nothing else suffices — a new clinical investigation.
  • One Graz-based company we worked with avoided 2-3 clinical investigations, saved EUR 400,000-500,000, and cut 1-1.5 years off the timeline by demonstrating that their measurement methods were covered by existing harmonised standards, and the Notified Body accepted the argument.

The story — EUR 400,000-500,000 and eighteen months, not spent

A few years ago we worked with a company in Graz building a device that combined two well-established measurement methods in a new way. The innovation was in the combination and the application, not in the underlying physics — the measurement methods themselves had been in clinical use for decades and were covered by recognised harmonised standards.

The initial clinical strategy they arrived with was the default one. Their advisors had told them to plan 2-3 clinical investigations to generate the clinical evidence for their technical file. The estimated cost was EUR 400,000-500,000. The estimated timeline was 1 to 1.5 years of investigation work alone, on top of everything else the company had to do to get to market. For a startup at their stage, this was not a difficult hurdle — it was the difference between shipping and not shipping.

We ran the Evidence Pass (the third pass of the Subtract to Ship framework for MDR — see post 65). The question it asks is not "what is the cheapest evidence," it is "what does the Regulation actually require, and what is the cheapest legitimate pathway to that requirement?" In this case the answer was already sitting in the GSPR chapter and the standards register. The established measurement methods were covered by harmonised standards. Compliance with those standards gave presumption of conformity with the relevant general safety and performance requirements for the measurement aspects of the device. What remained needing new clinical data was a much smaller scope — not the measurement methods themselves, but the specific claims about the combined application.

We documented the argument. We cited the standards. We wrote the clinical evaluation around literature and the standards-based presumption of conformity. The Notified Body reviewed it and accepted the approach. The 2-3 investigations never happened. EUR 400,000-500,000 stayed in the bank. The 1-1.5 years stayed in the runway.

This is not a loophole. It is the Regulation working as designed. Article 61 does not say "run a clinical investigation." It says generate sufficient clinical evidence, proportionate to the device, via a defined clinical evaluation process. The Evidence Pass forces that question to be asked before the default answer takes over.

What "sufficient clinical evidence" actually means under Article 61

MDR Article 61(1) requires that confirmation of conformity with the relevant general safety and performance requirements set out in Annex I under the normal conditions of the intended use of the device, and the evaluation of the undesirable side-effects and of the acceptability of the benefit-risk-ratio referred to in Sections 1 and 8 of Annex I, shall be based on clinical data providing sufficient clinical evidence, including where applicable relevant data from post-market surveillance (PMS) under Annex III and the post-market clinical follow-up (PMCF) plan required under Annex XIV Part B.

Three words in that sentence carry the weight. "Sufficient." "Clinical evidence." "Proportionate" — which appears in Article 61(11) and governs how the evaluation scales to the device.

"Sufficient" is not defined as a volume. It is defined by function: enough clinical data to confirm, to the level required by the class and risk of the device, that the GSPRs are met and that the benefit-risk ratio is acceptable. What is sufficient for an adhesive bandage is nothing like what is sufficient for a pacemaker — and the Regulation does not pretend otherwise.

"Clinical evidence" is the output of the clinical evaluation process. It is the combined body of clinical data and clinical evaluation results that supports the claims made about the device. Clinical data itself can come from clinical investigation(s) of the device concerned, clinical investigation(s) or other studies reported in scientific literature of a device for which equivalence can be demonstrated, reports published in peer-reviewed scientific literature on other clinical experience of either the device in question or a device for which equivalence can be demonstrated, and clinically relevant information coming from PMS, in particular the PMCF. Article 61 recognises all of these as legitimate sources. The choice between them depends on what the device is, what it does, and what evidence already exists in the world.

"Proportionate" is the word that makes Class I feasible. Article 61(11) states explicitly that the clinical evaluation and its documentation shall be updated throughout the life cycle of the device concerned with clinical data obtained from the implementation of the manufacturer's PMCF plan and the PMS plan, and that for Class III devices and implantable devices, the summary of safety and clinical performance referred to in Article 32 shall be updated at least annually with such data. The scale of the clinical evaluation tracks the scale of the device.

How proportionality applies to Class I

Class I is the lowest-risk class in the MDR. Most Class I devices are non-invasive, do not incorporate a measurement function in the regulatory sense, are not reusable surgical instruments, and are not sterile at placing on the market. The four special subcategories — Class Is (sterile), Class Im (with measuring function), Class Ir (reusable surgical instruments), and devices covered by the "r" subcategory from Article 52(7a) — have additional Notified Body involvement for their specific aspects.

For baseline Class I devices, the conformity assessment route is self-certification. The manufacturer prepares and maintains the technical documentation, the EU declaration of conformity, and the CE marking without Notified Body involvement for the device itself. But — and this is where many founders go wrong — self-certification does not mean "no clinical evaluation." It means the clinical evaluation is performed by the manufacturer under their own responsibility, without a Notified Body reviewing every page.

The proportionality principle says that for a low-risk Class I device with a well-understood technology and established clinical context, the clinical evaluation can be short, literature-based, and focused. It still must exist. It still must be documented in the technical file per Annex II. It still must be updated. What it does not have to be is a multi-year clinical investigation programme.

The temptation for founders is to interpret "proportionate" as permission to do nothing. That is not what the word means. An auditor — or a market surveillance authority inspecting a product after a complaint — will expect to see a real clinical evaluation report, built to the Annex XIV Part A structure, with a defined scope, identified data, appraised data, and a clinical evaluation conclusion. "We did not think we needed one" is not a defensible answer.

The hierarchy of evidence sources

For a Class I device, the practical hierarchy of clinical data sources runs from cheapest to most expensive as follows.

Literature on the state of the art and on the device category. A structured literature review covering the relevant clinical field establishes the state of the art, the clinical background, and the benchmark performance of devices in the same category. For many Class I devices this is the single largest evidence source. Done well, it is a real piece of work — defined search strategy, documented databases, documented inclusion and exclusion criteria, appraisal of the retrieved literature, and a conclusion that ties back to the GSPRs. MEDDEV 2.7/1 Rev 4 (June 2016) remains a widely used methodological reference for how to structure this work, and continues to be referenced alongside the MDR text where MDCG documents do not cover a specific methodological question.

Equivalence to an existing device. MDCG 2020-5 (April 2020) governs how equivalence is demonstrated under the MDR. Equivalence must be established across technical, biological, and clinical characteristics, and the bar is considerably higher than it was under the Directives. For Class I devices the equivalence pathway is usable but rarely the full answer on its own — it is more often a supporting element within a literature-based clinical evaluation.

Harmonised standards covering established technologies or measurement methods. Where a harmonised standard covers the relevant technology and gives presumption of conformity with specific GSPRs, compliance with that standard does part of the work that would otherwise have to be done with clinical data. This is exactly what happened in the Graz story. It does not eliminate the clinical evaluation — it reduces the scope of clinical data that has to be generated.

Data from post-market surveillance and PMCF. Once a device is on the market, PMS data and PMCF data feed back into the clinical evaluation and update the clinical evidence. For a new Class I device this is not a pre-market option, but the PMCF plan must still be drafted before CE marking because it is part of the technical documentation.

New clinical investigation. For Class I devices, a new clinical investigation is the exception, not the rule. It is appropriate when nothing else produces sufficient evidence, when the claims extend beyond what literature and equivalence can support, or when the device is genuinely novel in a way that existing data cannot address. For the great majority of Class I devices, none of those conditions hold.

When Class I devices can rely on literature alone

A literature-only clinical evaluation is defensible when three conditions are met. First, the intended purpose — as defined in Article 2(12) as the use for which a device is intended according to the data supplied by the manufacturer on the label, in the instructions for use or in promotional or sales materials or statements and as specified by the manufacturer in the clinical evaluation — is narrow, specific, and consistent with uses that are already reflected in the published literature. Second, the device technology is not novel and is well-represented in the scientific and clinical literature. Third, the claims made about the device do not exceed what the literature supports.

Where these conditions hold, a rigorous literature review tied back to each relevant GSPR, supplemented by the risk management output from EN ISO 14971:2019+A11:2021, produces sufficient clinical evidence for a Class I device. The clinical evaluation report should still cover the full Annex XIV Part A structure — scope definition, identification of clinical data, appraisal, analysis, and conclusion — but the clinical data input is literature rather than new investigation.

When existing harmonised standards obviate clinical investigation

This is the Graz pattern. The device uses a measurement method or a technology that is already covered by a harmonised standard. The standard provides presumption of conformity with the GSPRs it addresses. The clinical evaluation cites the standards compliance as part of the argument that the device meets the relevant GSPRs, and focuses new clinical data generation only on the aspects of the device that are not already covered.

This approach works when the harmonised standards genuinely cover the aspect in question, when the device's application is consistent with what the standard addresses, and when the Notified Body (for the subcategories of Class I that involve one) or the manufacturer's own clinical reviewer can defend the argument. In the Graz case, the Notified Body accepted the approach. That acceptance was not automatic — it required a clearly written clinical evaluation that walked the reviewer through the logic, cited the standards, and tied everything back to the GSPRs. The argument had to be made. Once made, it held.

The PMCF obligation even for Class I

Annex XIV Part B requires a PMCF plan for the device. Class I is not exempt from the PMCF obligation — what is different is that the plan can be lighter, proportionate to the risk. For a low-risk Class I device, PMCF can often be based on PMS data streams (complaints, returns, user feedback, literature surveillance) rather than on a dedicated PMCF study. Where the clinical evaluation has identified residual gaps or uncertainties that PMS cannot address, a more active PMCF activity may be required.

The key point for founders: the PMCF plan is a pre-market deliverable. It lives in the technical documentation at the time of CE marking. "We'll figure out PMCF after we ship" is not a valid answer. Draft the plan before CE, run it after CE, and feed the data back into the clinical evaluation on an ongoing basis.

Common Class I clinical evaluation mistakes

  • Treating Class I as exempt from clinical evaluation. Article 61(1) applies regardless of class.
  • Running an unstructured literature search that cannot be reproduced by an auditor or market surveillance authority. The search strategy, databases, dates, and criteria must be documented.
  • Confusing scientific background material with clinical data. A review of the underlying physics or chemistry is context, not clinical data.
  • Overclaiming in the intended purpose beyond what the clinical data supports. If the literature covers use A and the intended purpose claims A and B, the evidence is not sufficient for B.
  • Skipping the PMCF plan because the device is Class I. Annex XIV Part B still applies.
  • Assuming that equivalence is easier under MDR than it was under the Directives. MDCG 2020-5 raised the bar substantially, especially on biological and technical equivalence.
  • Defaulting to "we need clinical investigations" without first running the Evidence Pass to see whether literature, equivalence, and standards already cover the question.

The Subtract to Ship angle — the Evidence Pass

The Evidence Pass (the third pass in the Subtract to Ship framework for MDR) asks one question. Before committing to any evidence pathway, what is the cheapest legitimate source of evidence that satisfies the relevant GSPR for this specific claim about this specific device? Work that question through the hierarchy — literature first, equivalence second, standards third, PMS/PMCF as the pre-market plan, and new clinical investigation as the last resort — and the default over-scoping that kills Class I projects disappears.

Subtraction here means cutting clinical investigations that are not actually needed, cutting literature searches that go beyond the claims being made, and cutting equivalence arguments that the data will not support. It does not mean cutting the clinical evaluation itself. The obligation under Article 61 is absolute. The scale of work to meet it is not.

Reality Check — Where do you stand?

  1. Have you written down the intended purpose of your Class I device in the exact language of Article 2(12), and is the clinical evidence scoped to match that intended purpose and nothing more?
  2. Do you have a documented clinical evaluation report that follows the Annex XIV Part A structure, even if literature-based?
  3. For each claim you make about the device, can you point to the specific clinical data source that supports it?
  4. Have you run the Evidence Pass — literature, equivalence, harmonised standards — before deciding whether a clinical investigation is necessary?
  5. Is your PMCF plan drafted and in the technical documentation, or are you planning to write it after CE marking?
  6. Would an auditor or a market surveillance authority be able to reproduce your literature search from the documentation you currently have?
  7. Does your clinical evaluation tie each conclusion back to a specific GSPR in Annex I?

Frequently Asked Questions

Do Class I devices need a clinical evaluation report under MDR? Yes. MDR Article 61(1) requires clinical evaluation for every medical device, including Class I. The clinical evaluation must be documented in a clinical evaluation report and included in the technical documentation per Annex II. What varies with class is the scale and the mix of evidence sources, not whether the obligation exists.

Can a Class I clinical evaluation be based only on literature? In many cases, yes. Where the intended purpose is narrow, the technology is well-represented in the scientific literature, and the claims made about the device do not exceed what the literature supports, a structured literature review tied to each relevant GSPR can produce sufficient clinical evidence for a Class I device. The review must be rigorous, reproducible, and documented in line with Annex XIV Part A.

When is a clinical investigation required for a Class I device? When literature, equivalence, and reliance on harmonised standards together do not produce sufficient evidence for the claims being made about the device. This is the exception rather than the rule for Class I. For most Class I devices a new investigation is not required, provided the Evidence Pass is run properly and the resulting clinical evaluation defends the conclusion.

What does Article 61(10) mean for Class I devices? Article 61(10) recognises that for some devices — typically simple, low-risk devices — demonstrating conformity with the GSPRs based on clinical data may not be appropriate. In that case the manufacturer must justify, based on the output of the risk management process and on consideration of the specifics of the device-body interaction, the clinical performances intended, and the claims of the manufacturer, why non-clinical testing methods including performance evaluation, bench testing, and pre-clinical evaluation are deemed adequate. This is a narrow provision and does not eliminate the clinical evaluation — it changes the type of data that goes into it.

Is PMCF required for Class I devices? Yes. Annex XIV Part B applies to all classes. The PMCF plan must exist before CE marking and must be proportionate to the device. For a low-risk Class I device the plan can be lighter and often relies on PMS data streams rather than a dedicated PMCF study, but the plan itself is not optional.

Sources

  1. Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, Article 2(12) (intended purpose), Article 61 (clinical evaluation), Article 61(10) and 61(11) (sufficient clinical evidence and proportionality), Annex I (general safety and performance requirements), Annex II (technical documentation), Annex III (technical documentation on PMS), Annex XIV Part A (clinical evaluation) and Part B (PMCF). Official Journal L 117, 5.5.2017.
  2. MDCG 2020-5 — Clinical Evaluation — Equivalence: A guide for manufacturers and notified bodies, April 2020.
  3. MEDDEV 2.7/1 revision 4 — Guidelines on Medical Devices — Clinical Evaluation: A Guide for Manufacturers and Notified Bodies under Directives 93/42/EEC and 90/385/EEC, June 2016. Legacy document still widely referenced for clinical evaluation methodology under MDR where MDCG documents do not cover a specific methodological question.
  4. EN ISO 14971:2019 + A11:2021 — Medical devices — Application of risk management to medical devices.

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 Class I pathway rewards founders who read the Regulation carefully before committing to expensive evidence pathways — the Evidence Pass exists to make that reading happen before the invoices do.