CER Rejection: Common Reasons Clinical Evaluation Reports Fail EU MDR Review

Why Clinical Evaluation Reports Are Rejected Under EU MDR – and How to Avoid It

Introduction

Clinical Evaluation Reports (CERs) play a central role in demonstrating the safety and performance of medical devices under the EU MDR framework. The evidence presented within a CER must support clinical claims, align with post-market data, and withstand detailed scrutiny during regulatory review.

In regulatory settings, CERs are frequently challenged during assessment. These challenges are rarely the result of a single issue. More often, they reflect gaps in how clinical evidence is identified, evaluated, and integrated across the broader regulatory framework, including post-market surveillance and ongoing clinical evaluation activities.

This article outlines common reasons CERs are rejected, together with practical considerations to support the development of more robust and defensible clinical evaluations.

Why CERs Are Challenged

CERs are assessed within a complex regulatory environment, where multiple sources of evidence must be aligned and consistently presented. Under EU MDR, expectations extend beyond the presence of data to how that data is selected, evaluated, and integrated across the clinical evaluation process.

In many cases, challenges arise not from a single deficiency, but from misalignment across different components of the evidence base. Literature review, post-market surveillance, and Post-Market Clinical Follow-Up (PMCF) activities are often developed separately, increasing the risk of inconsistencies in how evidence is interpreted and reported.

In addition, evolving regulatory expectations and increasing scrutiny from Notified Bodies place greater emphasis on methodological transparency, critical appraisal, and clear justification of clinical conclusions. Where these elements are not sufficiently addressed, gaps may become apparent during review.

Common CER Challenges in Practice

The following sections outline commonly encountered challenges in Clinical Evaluation Reports, together with their potential impact on the strength and defensibility of clinical evaluation.

Insufficient Clinical Evidence

CERs may be challenged where the available clinical evidence does not adequately support the intended use, safety profile, or performance claims of the device. This may include reliance on limited, outdated, or non-representative data.

Impact:
This can weaken the overall clinical argument and limit the ability to demonstrate a favourable benefit–risk profile, increasing the likelihood of further questions or requests for additional data.

Inadequate Literature Review Methodology

Gaps in search strategy development, incomplete documentation, or limited transparency in how literature has been identified and selected can reduce the reliability of the review process.

Impact:
A lack of reproducibility may raise concerns during regulatory assessment, potentially leading to requests for clarification or the need to repeat parts of the literature review.

Lack of Critical Appraisal

Where included studies are not assessed using a structured and transparent approach for quality, relevance, and risk of bias, the resulting evidence base may lack depth and context.

Impact:
This can result in conclusions that are not sufficiently supported, reducing confidence in the clinical evaluation and increasing scrutiny from Notified Bodies. In such cases, the CER may rely on descriptive summaries rather than a synthesised and critically evaluated evidence base.

Misalignment with State of the Art (SOTA)

Failure to adequately position the device within the current state of the art may result in an incomplete or unclear understanding of its clinical value relative to existing alternatives.

Impact:
This can limit the strength of the clinical justification and raise questions regarding the relevance and completeness of the evaluation.

Inconsistencies Across CER, PMS, and PMCF

Where data and conclusions are not aligned across Clinical Evaluation Reports, post-market surveillance, and Post-Market Clinical Follow-Up activities, inconsistencies may emerge in how safety and performance are presented.

Impact:
Such discrepancies can raise concerns during review and require additional effort to reconcile differences across documentation. This may also include gaps in alignment between the Clinical Evaluation Plan (CEP), the CER, and associated post-market activities.

Unclear or Unsupported Benefit–Risk Evaluation

A CER may be challenged where the benefit–risk profile is not clearly articulated or sufficiently supported by the available evidence.

Impact:
This can undermine the overall conclusion of the clinical evaluation and lead to requests for further justification or clarification.

Collectively, these challenges reflect gaps in alignment with EU MDR expectations, particularly in relation to clinical evidence, methodological transparency, and consistency across regulatory documentation.

Key Questions to Consider Before Submitting a CER

Key components supporting a structured and defensible Clinical Evaluation Report

Before submission, it may be useful to assess the robustness of the Clinical Evaluation Report by considering a series of structured questions:

Is the clinical strategy clearly defined?

Are the intended use, clinical claims, and evidence requirements consistently established and reflected throughout the evaluation?

Is the literature search structured and reproducible?

Have databases, search terms, filters, and inclusion and exclusion criteria been clearly documented to support transparency?

Has the evidence been critically appraised?

Have included studies been evaluated for quality, relevance, and potential bias using a structured and transparent approach?

Is there alignment across CER, PMS, and PMCF activities?

Are safety signals, data interpretation, and conclusions consistently presented across all regulatory documentation?

Is the device positioned within the current state of the art?

Does the evaluation clearly contextualise findings relative to comparable devices and current clinical practice?

Is the evidence base current and actively maintained?

Has recent data been incorporated, and is the evaluation aligned with ongoing post-market activities?

Addressing these questions prior to submission can support a more consistent, transparent, and defensible clinical evaluation.

Consequences of CER Deficiencies in Regulatory Review

The consequences of deficiencies in a Clinical Evaluation Report are often most apparent during regulatory review, where both the evidence and the processes used to generate it are subject to detailed scrutiny. In these settings, gaps in methodology, inconsistencies across documentation, or insufficient justification of conclusions may prompt requests for clarification or additional supporting evidence.

This may lead to delays in review timelines, increased workload to address identified gaps, and, in some cases, difficulty demonstrating that the benefit–risk profile of the device is adequately supported. Where inconsistencies extend across Clinical Evaluation Reports (CERs), post-market surveillance (PMS), and Post-Market Clinical Follow-Up (PMCF) activities, the effort required to reconcile these differences may be substantial.

Importantly, these challenges are not only regulatory in nature. Clinical evaluation plays a central role in ensuring that medical devices are supported by appropriate evidence of safety and performance, highlighting the broader implications for patient safety and the reliability of clinical outcomes.

What Happens If a CER Is Challenged – and How to Respond

Challenges to a Clinical Evaluation Report are a recognised aspect of the regulatory review process. Given the complexity of EU MDR requirements and the volume of evidence involved, questions or requests for clarification may arise even in well-structured submissions.

When a CER is challenged, this typically takes the form of detailed questions, requests for additional justification, or identification of gaps in evidence, methodology, or alignment across documentation. These observations provide an opportunity to further strengthen the clinical evaluation and reinforce the reliability of its conclusions.

In practice, deficiencies identified during regulatory review are typically communicated through formal assessment outcomes issued by the Notified Body, outlining areas requiring clarification, justification, or correction. These communications may include defined timelines for response, after which updated documentation is expected to be resubmitted through the appropriate regulatory pathway for further review.

An effective response is structured and proportionate to the issues raised. This may include revisiting literature search strategies, updating the evidence base, strengthening critical appraisal, or ensuring alignment across Clinical Evaluation Reports (CERs), post-market surveillance (PMS), and Post-Market Clinical Follow-Up (PMCF) activities.

From a regulatory perspective, the ability to identify and address gaps in a transparent and systematic manner is often viewed positively. It demonstrates that processes are not only established, but actively maintained and capable of supporting continuous improvement.

In this context, the focus shifts from avoiding challenges entirely to managing them effectively within a structured regulatory framework.

Conclusion

A strong Clinical Evaluation Report is not defined solely by the absence of deficiencies, but by the ability to manage complexity, maintain alignment, and respond effectively to gaps as they arise. The challenges outlined in this article reflect the realities of working within an evolving regulatory environment, where clinical evidence must be continuously evaluated, integrated, and maintained.

As such, the focus extends beyond avoiding challenges to how clinical evaluation processes are designed, controlled, and improved over time. Approaches that support consistency across the evidence lifecycle are better positioned to meet regulatory expectations and ensure that clinical conclusions remain clear, transparent, and defensible.

In this context, the strength of a CER lies not only in its initial preparation, but in how it is sustained and adapted as new evidence emerges and regulatory requirements evolve.

It is also important to recognise that challenges or deficiencies identified during regulatory review are not uncommon and do not necessarily indicate failure of the device or its clinical evaluation as a whole. Rather, they form part of a structured process designed to ensure that conclusions are reliable, evidence-based, and aligned with the current state of the art. When approached constructively, regulatory feedback can support the refinement of clinical evaluation and contribute to the ongoing safety and performance of medical devices.

If you are preparing a Clinical Evaluation Report or responding to a Notified Body challenge, Citemeds supports medical device manufacturers with CER writing, literature review, and clinical evaluation services designed to meet EU MDR expectations. Get in touch to discuss your requirements.

Frequently Asked Questions

What are the most common reasons a Clinical Evaluation Report is rejected?

The most common reasons Clinical Evaluation Reports are challenged or rejected under EU MDR relate to insufficient clinical evidence, inadequate literature review methodology, lack of critical appraisal, and inconsistencies across CER, PMS, and PMCF documentation. Notified Bodies increasingly scrutinise not just whether evidence is present but how it has been identified, evaluated, and integrated into a coherent benefit-risk conclusion. Submissions that rely on descriptive summaries rather than critically synthesised evidence are particularly vulnerable to challenge.

What happens if a CER fails Notified Body review?

If a Clinical Evaluation Report fails to meet Notified Body expectations, manufacturers typically receive a formal assessment outcome identifying areas requiring clarification, additional justification, or correction. These communications usually include defined timelines for response. Depending on the severity of the gaps identified, this may require revisiting the literature search strategy, strengthening critical appraisal, updating the evidence base, or reconciling inconsistencies across CER, PMS, and PMCF documentation. In some cases, significant rework is required before the submission can progress.

How often does a CER need to be updated under EU MDR?

Under EU MDR, a Clinical Evaluation Report is not a one-time document. It must be updated regularly throughout the device lifecycle, particularly when new post-market surveillance or PMCF data becomes available that could affect the evaluation’s conclusions. For higher-risk devices, this typically means annual reviews. Treating the CER as a static document is one of the most common compliance risks manufacturers face and is a frequent source of challenge during Notified Body assessments.

What is the difference between a CER and a Clinical Evaluation Plan?

A Clinical Evaluation Plan (CEP) is the document that defines the scope, methodology, and evidence requirements for the clinical evaluation — including the intended use, clinical claims, and planned literature search strategy. The Clinical Evaluation Report (CER) is the output document that presents the results of that evaluation, synthesising all identified clinical evidence into a benefit-risk conclusion. The CEP must be established before the evaluation begins, and the CER must demonstrate that the methodology defined in the CEP was followed consistently.

What is the role of the state of the art in a CER?

The state of the art (SOTA) analysis is a required component of the Clinical Evaluation Report under EU MDR. It establishes the current standard of care by reviewing similar technologies, alternative treatments, and existing clinical evidence in the relevant medical field. The subject device must be evaluated against this baseline to demonstrate that its benefit-risk profile is acceptable relative to currently available alternatives. Failure to adequately position the device within the state of the art is a common reason CERs are challenged during regulatory review.

What is critical appraisal and why does it matter in a CER?

Critical appraisal is the structured process of evaluating the quality, relevance, and risk of bias of studies included in a literature review. In the context of a Clinical Evaluation Report, it ensures that clinical conclusions are based on reliable, high-quality evidence rather than a simple collection of available data. Notified Bodies expect to see evidence that included studies have been systematically assessed — not just listed or summarised. Where critical appraisal is absent or superficial, submissions are at significantly higher risk of challenge.

How should inconsistencies between CER, PMS, and PMCF be addressed?

Inconsistencies across Clinical Evaluation Reports, post-market surveillance, and PMCF documentation are a common source of challenge during regulatory review. They typically arise when these activities are developed separately rather than as part of an integrated evidence lifecycle. Addressing them requires ensuring that safety signals, data interpretation, and clinical conclusions are consistently presented across all regulatory documentation — and that the CER is updated to reflect new findings emerging from PMS and PMCF activities as they become available.

What do Notified Bodies look for when reviewing a CER?

Notified Bodies assess Clinical Evaluation Reports against the requirements of EU MDR and relevant guidance including MEDDEV 2.7/1 Revision 4. Key areas of focus include the comprehensiveness and reproducibility of the literature search strategy, the quality and relevance of included clinical evidence, the depth of critical appraisal, the clarity of the benefit-risk evaluation, and the consistency of conclusions across CER, PMS, and PMCF documentation. They also assess whether the state of the art has been adequately addressed and whether the evaluation reflects the current clinical landscape for the device in question.