Why Notified Bodies Reject CERs: 10 Mistakes You’re Still Making
You submit your Clinical Evaluation Report. Three weeks later, the Notified Body sends back a twelve-page deficiency letter. Half the issues could have been prevented if you had known what reviewers actually look for. The other half reveal structural problems that trace back to the planning phase.
In This Article
- 1. Missing or Weak Clinical Development Plan
- 2. Insufficient Literature Search Strategy
- 3. Unjustified Equivalence Claims
- 4. Inadequate Appraisal of Individual Studies
- 5. Weak or Missing Benefit-Risk Analysis
- 6. Failure to Address State of the Art
- 7. Insufficient PMCF Planning and Integration
- 8. Inadequate Response to Similar Device Issues
- 9. Poor Integration of PMS and Vigilance Data
- 10. Lack of Qualified Clinical Evaluator Involvement
- What This Means for Your Next Submission
I review CERs every week. Some pass smoothly through Notified Body assessment. Most do not.
The rejections follow patterns. The same structural errors appear across manufacturers, across device types, across Notified Bodies. These are not random failures. They reflect systematic misunderstandings of what MDR Annex XIV actually requires and how reviewers interpret those requirements.
This post walks through the ten most common mistakes that trigger CER rejections. Each one is drawn from real deficiency letters and audit observations. Each one can be avoided if you understand the underlying logic.
1. Missing or Weak Clinical Development Plan
Many manufacturers start writing the CER without a Clinical Development Plan or Clinical Evaluation Plan that clearly defines the evaluation strategy.
The Notified Body reviewer opens your CER. They look for the plan that guided your literature search, your equivalence approach, your data gap strategy. If that plan is missing, vague, or written after the fact, the entire CER loses credibility.
The Clinical Evaluation Plan is generic, undated, or does not match the scope and methods described in the CER. Reviewers conclude the CER was written without strategic planning.
MDR Annex XIV Part A Section 1 requires manufacturers to plan clinical evaluation activities. That plan must be specific, dated, and aligned with device risk and novelty. It must precede the execution of the evaluation.
When the plan is absent or weak, reviewers question whether the manufacturer truly understands the clinical uncertainties of their device.
2. Insufficient Literature Search Strategy
You perform a literature search. You document it in the CER. But the Notified Body rejects it because the search strategy is not reproducible, not comprehensive, or not justified.
This mistake appears constantly. Manufacturers describe search terms and databases but do not explain the rationale. They do not justify inclusion and exclusion criteria. They do not show how the search addresses specific clinical questions.
MDCG 2020-6 provides clear guidance on literature review methodology. Reviewers expect search strategies that align with that guidance. They expect documentation that another qualified person could reproduce the search and reach similar results.
A strong literature search is not just about volume of articles. It is about strategic targeting of specific clinical questions, transparent methodology, and clear justification for boundaries.
When the search strategy is weak, the entire evidence base becomes questionable. Reviewers cannot trust that relevant data was not missed.
3. Unjustified Equivalence Claims
Equivalence is the most rejected section of most CERs I review.
Manufacturers claim equivalence to a device without demonstrating technical, biological, and clinical equivalence as required by MDCG 2020-5. They compare devices at a high level but ignore critical differences in materials, design, indications, or patient populations.
Notified Bodies apply strict criteria. They look for side-by-side comparison tables. They expect you to address every difference and justify why each difference does not impact clinical safety or performance. They expect clinical data from the equivalent device that is relevant and sufficient.
Equivalence is claimed based on similar intended use alone, without rigorous demonstration of technical and biological equivalence. Clinical data from the equivalent device is outdated, sparse, or not applicable to the claimed indications.
If you cannot demonstrate equivalence rigorously, do not claim it. A weak equivalence claim is worse than no claim. It signals to the reviewer that you do not understand the standard.
The consequence is clear: plan for your own clinical data or ensure equivalence is bulletproof before submission.
4. Inadequate Appraisal of Individual Studies
You include ten studies in your CER. But you do not critically appraise them.
Critical appraisal means evaluating study design, risk of bias, relevance to your device, and applicability to your indications and patient population. It means explaining why each study contributes to your safety and performance conclusions.
Many CERs simply summarize studies without appraisal. The reviewer reads the summaries and asks: How do you know this data is reliable? How do you know it applies to your device?
MDCG 2020-6 requires systematic appraisal of each data source. Reviewers expect structured appraisal using recognized frameworks. They expect transparency about study limitations and how those limitations affect the weight of evidence.
Critical appraisal is not optional. It transforms a list of studies into a reasoned evidence base. Without it, your CER is a literature review, not a clinical evaluation.
5. Weak or Missing Benefit-Risk Analysis
The benefit-risk analysis is the heart of the CER. Yet many manufacturers treat it as a checkbox exercise.
They list benefits. They list risks. They conclude the balance is favorable. But they do not analyze trade-offs. They do not discuss clinical contexts where risks may outweigh benefits. They do not integrate PMS data or complaint trends.
MDR Article 61(1) and Annex I require a benefit-risk analysis that accounts for the state of the art, residual risks, and intended patient population. Reviewers expect depth. They expect you to address uncertainties, alternative treatments, and real-world use conditions.
Benefit-risk analysis is superficial, does not integrate post-market data, and does not address specific patient subgroups or use scenarios where risk profiles differ.
A weak benefit-risk section signals to the Notified Body that you have not fully considered device safety in real-world contexts.
6. Failure to Address State of the Art
MDR Article 2(43) defines state of the art as the developed stage of technical capability at a given time. Your CER must demonstrate your device meets current standards of safety and performance.
Many CERs ignore this requirement. They do not compare the device to current alternatives. They do not discuss emerging technologies or evolving clinical practice. They do not justify why their design choices align with state of the art.
Reviewers expect you to position your device within the current clinical and technological landscape. If newer, safer alternatives exist and you do not address them, the CER is incomplete.
State of the art is not static. Your CER must reflect awareness of current clinical practice, competing technologies, and evolving standards. Ignoring this makes your device appear clinically outdated.
7. Insufficient PMCF Planning and Integration
Post-Market Clinical Follow-up is required for most devices under MDR Annex XIV Part B. Yet many CERs treat PMCF as an afterthought.
The PMCF plan is generic. It does not address specific data gaps identified in the CER. It does not define clear objectives, methods, or timelines. And when PMCF data exists, it is not integrated into the CER analysis.
Notified Bodies expect tight integration. The CER should identify uncertainties. The PMCF plan should target those uncertainties. The PMCF results should feed back into updated CERs.
PMCF plan does not address CER data gaps. Existing PMCF data is not analyzed or integrated into the benefit-risk conclusions. The loop between evaluation and real-world evidence is broken.
A disconnected PMCF plan signals poor understanding of the iterative nature of clinical evaluation under MDR.
8. Inadequate Response to Similar Device Issues
Your device is in a class where field safety corrective actions, trend reports, or safety alerts exist for similar devices. Your CER does not address them.
Notified Bodies track these issues. They expect manufacturers to demonstrate awareness and explain how their device mitigates similar risks. If you ignore known issues in the device category, reviewers will ask why.
This requires proactive monitoring of similar devices, competitor recalls, and literature on adverse events. It requires transparent discussion in the CER about lessons learned and design or labeling strategies to avoid similar problems.
Proactive awareness of device category risks and transparent discussion of mitigation strategies builds trust with reviewers. Silence raises red flags.
9. Poor Integration of PMS and Vigilance Data
Your device is on the market. You have complaint data, vigilance reports, and trend analyses. But the CER does not integrate this data into the clinical evaluation.
MDR Annex XIV requires continuous updating of the CER based on post-market data. Reviewers expect to see PMS findings reflected in safety discussions, benefit-risk analysis, and residual risk assessment.
When PMS data is absent or presented in isolation, the CER appears static. It does not reflect real-world device performance. Notified Bodies will question whether your clinical evaluation is truly continuous.
PMS data is summarized but not analyzed in clinical terms. Vigilance trends are not linked to benefit-risk conclusions. The CER reads like a pre-market document even for devices with years of market history.
Integration of post-market data is not optional. It is the foundation of continuous evaluation.
10. Lack of Qualified Clinical Evaluator Involvement
The CER is written by regulatory staff or engineers without meaningful input from a qualified clinical evaluator.
Notified Bodies can tell. The clinical reasoning is weak. Medical terminology is used incorrectly. Clinical significance of findings is not interpreted. The document reads like a compliance exercise, not a medical evaluation.
MDR Annex XIV Part A Section 4 requires appropriately qualified personnel. MDCG 2020-5 emphasizes that clinical evaluation must be performed by persons with relevant expertise. Reviewers expect clinical judgment, not just regulatory documentation.
A CER is a medical document. It requires medical reasoning, clinical judgment, and healthcare perspective. Regulatory knowledge alone is not enough.
If your CER lacks clinical depth, reviewers will question the competence of your evaluation team. This is a fundamental credibility issue.
What This Means for Your Next Submission
These ten mistakes are preventable. They do not reflect lack of effort. They reflect misalignment between what manufacturers think is required and what Notified Bodies actually assess.
The CER is not a regulatory formality. It is the clinical foundation of your technical documentation. It must be strategic, evidence-based, and continuously updated. It must reflect clinical reasoning, not just regulatory compliance.
Before your next submission, review your CER against these ten points. Ask yourself: Would a Notified Body reviewer see rigorous clinical evaluation or see gaps that trigger deficiency letters?
The answer to that question determines whether your submission moves forward or stalls for months.
Peace,
Hatem
Clinical Evaluation Expert for Medical Devices
Follow me for more insights and practical advice.
Frequently Asked Questions
What is a Clinical Evaluation Report (CER)?
A CER is a mandatory document under MDR 2017/745 that demonstrates the safety and performance of a medical device through systematic analysis of clinical data. It must be updated throughout the device lifecycle based on PMCF findings.
How often should the CER be updated?
The CER should be updated whenever significant new clinical data becomes available, after PMCF activities, when there are changes to the device or intended purpose, and at minimum during annual reviews as part of post-market surveillance.
What causes CER rejection by Notified Bodies?
Common reasons include inadequate equivalence demonstration, insufficient clinical data for claims, poorly structured SOTA analysis, missing gap analysis, and lack of clear benefit-risk determination. Structure and logical flow are as important as the data itself.
Which MDCG guidance documents are most relevant for clinical evaluation?
Key documents include MDCG 2020-5 (Equivalence), MDCG 2020-6 (Sufficient Clinical Evidence), MDCG 2020-13 (CEAR Template), MDCG 2020-7 (PMCF Plan), and MDCG 2020-8 (PMCF Evaluation Report).
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Peace, Hatem
Your Clinical Evaluation Partner
Follow me for more insights and practical advice.
– Regulation (EU) 2017/745 (MDR), Annex XIV
– MDR Article 2(43) – State of the Art
– MDR Article 61(1) – Clinical Evaluation
– MDCG 2020-5: Clinical Evaluation – Equivalence
– MDCG 2020-6: Sufficient Clinical Evidence for Legacy Devices
– MDCG 2020-13: Clinical Evaluation Assessment Report Template
