Why your RWE is accepted in the US but rejected in Europe
I see this pattern repeatedly: a manufacturer submits real-world evidence that passed FDA review, assumes the same data will work for MDR compliance, and then receives a major deficiency from the Notified Body. The confusion is genuine. Both agencies claim to accept real-world evidence. But the frameworks diverge in ways that determine whether your clinical evaluation succeeds or fails.
In This Article
The acceptance of real-world evidence sounds like a solved problem. FDA published its framework. MDCG issued guidance. Manufacturers now collect RWE thinking it satisfies both systems.
But regulatory acceptance is not a checkbox. It is a judgment call made by reviewers who apply different standards, ask different questions, and weigh evidence according to different regulatory philosophies.
Understanding where FDA and EU approaches diverge is not academic. It determines how you design your evidence generation strategy, what you include in your clinical evaluation report, and whether your submission survives first review.
The Starting Point: What Real-World Evidence Actually Means
Real-world evidence is data collected outside the controlled conditions of a clinical trial. It includes registry data, electronic health records, insurance claims, patient-reported outcomes, and post-market surveillance reports.
Both FDA and EU regulators recognize that RCTs are not always feasible. For certain device types, randomizing patients is impractical. For others, the clinical question has already been answered in prior literature, and repeating controlled studies adds no value.
So both systems opened the door to real-world evidence. But they opened different doors.
FDA views RWE as an alternative pathway to generate evidence for regulatory decisions. The EU views RWE as supplementary data that must still fit within the MDR’s clinical evaluation framework.
That distinction matters more than most manufacturers realize.
FDA’s Real-World Evidence Framework
FDA published its RWE framework in 2018, with additional guidance documents following in 2021 and 2023. The framework is structured around two core concepts: real-world data (RWD) and the analytical methods used to derive real-world evidence.
FDA asks: Can this real-world data reliably answer the regulatory question?
The framework focuses on data quality, relevance, and reliability. If a manufacturer can demonstrate that the data source is fit for purpose, that the analytical methods are sound, and that the results address the regulatory question, FDA will consider the evidence.
This approach is pragmatic. FDA evaluates each RWE submission on a case-by-case basis. There is no rigid requirement that RWE must replicate the structure of a clinical trial. The question is whether the evidence supports the regulatory decision being requested.
For post-market studies, FDA explicitly accepts real-world evidence as part of 522 post-market surveillance orders. Manufacturers can propose RWE studies instead of prospective clinical trials, provided the study design is adequate.
FDA’s approach is question-driven. If RWE answers the regulatory question with sufficient reliability, it can stand as primary evidence.
But the EU operates differently.
The MDR’s Clinical Evaluation Requirements
Under MDR Article 61 and Annex XIV, manufacturers must demonstrate conformity with safety and performance requirements through clinical evaluation. The regulation does not mention real-world evidence by name. It specifies clinical data.
Clinical data is defined as information concerning safety or performance obtained from the use of the device. This includes clinical investigation data, data from scientific literature, and data from PMCF activities.
MDCG 2020-6 provides guidance on sufficient clinical evidence. The document clarifies that clinical data must be sufficient in amount and quality to demonstrate compliance with the general safety and performance requirements.
The critical difference: MDR does not treat RWE as a separate category. Real-world data is simply clinical data that was generated outside a clinical investigation. It is evaluated using the same criteria as any other clinical data.
The question is not whether the data is real-world or trial-based. The question is whether the data is sufficient.
Manufacturers assume that because FDA accepted their RWE study, it automatically satisfies MDR requirements. Notified Bodies then reject the same data because it does not address all applicable general safety and performance requirements.
Where the Systems Diverge in Practice
The divergence becomes visible when you examine how each system evaluates the same dataset.
1. Scope of the Evidence
FDA typically evaluates RWE in relation to a specific regulatory question. For example: Does this device reduce hospital readmissions? Does it perform as well as the predicate device in real-world use?
The EU requires clinical data to cover all applicable general safety and performance requirements in Annex I. Even if your RWE study answers one clinical question, the Notified Body will ask whether the data addresses device design, biocompatibility, clinical benefits, residual risks, and acceptability of the benefit-risk ratio.
A single RWE study rarely covers all GSPRs. That is why RWE in the EU context is almost always supplementary.
2. Completeness of the Clinical Dataset
FDA evaluates whether the submitted RWE is sufficient to support the specific claim or indication. If the evidence supports the decision, the review proceeds.
Notified Bodies evaluate whether the entire clinical dataset is sufficient. This includes literature, equivalence data, clinical investigations, and PMCF. RWE is one input into the overall evaluation.
If you submit only RWE without literature review, equivalence justification, or PMCF plan, the Notified Body will issue a major deficiency regardless of how strong your RWE study is.
3. Study Design Expectations
FDA does not require RWE studies to replicate randomized controlled trial designs. The framework explicitly allows for single-arm studies, retrospective analyses, and pragmatic designs.
The EU does not prohibit these designs either. But MDCG 2020-6 emphasizes that the level of clinical evidence should correspond to the risk class and novelty of the device. For higher-risk devices or novel technologies, observational RWE alone is rarely sufficient.
Notified Bodies expect manufacturers to justify why the chosen study design is adequate. If the device poses significant residual risks, a retrospective registry analysis may not be considered sufficient even if FDA accepted it.
Manufacturers present a single-arm RWE study for a Class IIb device with novel claims and do not explain why a controlled study was not feasible. The Notified Body rejects the evidence as insufficient.
PMCF and Real-World Evidence
Post-market clinical follow-up is where real-world evidence fits most naturally in the EU system. PMCF is required under MDR Article 61(11) and involves the proactive collection of clinical data after the device is placed on the market.
PMCF methods include literature surveillance, registry participation, surveys, and clinical studies. Many of these methods generate real-world data.
The difference from FDA: PMCF is mandatory. It is not an optional alternative to pre-market studies. It is part of the continuous evaluation of safety and performance.
Manufacturers often misunderstand this. They think that conducting a PMCF study allows them to skip pre-market clinical investigations. But PMCF does not replace the need for sufficient pre-market clinical data.
Notified Bodies expect pre-market clinical data to demonstrate initial conformity. PMCF then confirms that performance remains acceptable and detects emerging risks.
If your pre-market dataset is weak, a strong PMCF plan does not compensate. You still need sufficient clinical evidence at the point of initial certification.
In the EU, RWE generated through PMCF is expected. It does not earn you regulatory credit the way it might with FDA. It is baseline compliance.
Practical Implications for Regulatory Strategy
If you are developing a clinical evidence strategy for both FDA and EU markets, you cannot assume that one dataset fits both systems.
Start by identifying the regulatory question for FDA and the applicable GSPRs for the EU. Map your evidence sources to both.
If you plan to submit RWE to FDA, ensure the study design meets FDA’s expectations for data quality and relevance. Use FDA’s RWE framework guidance documents to structure your submission.
For the EU, position your RWE study as part of the broader clinical evaluation. Include literature review, equivalence analysis if applicable, and a PMCF plan that addresses all GSPRs.
Do not rely solely on RWE for high-risk devices unless you have a strong justification for why controlled studies are not feasible. Notified Bodies will question the adequacy of observational data for Class IIb and Class III devices.
If your RWE study was conducted post-market in the US, present it as PMCF data in the EU. Do not frame it as a substitute for pre-market clinical investigations unless your device is low-risk and you have solid equivalence justification.
A manufacturer submits a 510(k) with RWE and then uses the same dataset as the sole clinical evidence for CE marking. The Notified Body issues a major deficiency because the data does not address all GSPRs and no PMCF plan is provided.
What Reviewers Actually Look For
FDA reviewers evaluate whether your RWE study answers the regulatory question. They look at data provenance, study design, bias mitigation, and statistical methods. If those elements are sound, the evidence is accepted.
Notified Body reviewers evaluate whether your entire clinical dataset is sufficient to demonstrate conformity. They look at the completeness of the evaluation, the adequacy of each data source, and whether residual risks are addressed.
When you submit RWE to a Notified Body, expect these questions:
– What other clinical data do you have beyond this study?
– How does this study address the applicable general safety and performance requirements?
– Why is this study design adequate for your device’s risk class?
– What is your PMCF plan, and how will it confirm long-term performance?
If you cannot answer those questions clearly, your submission will not pass review.
Moving Forward
Real-world evidence is not a shortcut. It is a data source that can strengthen your clinical evaluation when used correctly.
FDA accepts RWE as primary evidence when the data reliably answers the regulatory question. The EU accepts RWE as part of the clinical dataset when it contributes to demonstrating conformity with GSPRs.
The key is knowing which system you are working within and structuring your evidence accordingly.
If you treat FDA acceptance as proof that your evidence is sufficient for the EU, you will face deficiencies. If you design your RWE strategy with both systems in mind, you can generate data that satisfies both.
The next post will address how to structure clinical evaluation reports when your evidence includes real-world data. The report structure determines whether reviewers understand your rationale or question your entire approach.
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). MDCG 2020-6, FDA RWE Framework
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Peace, Hatem
Your Clinical Evaluation Partner
Follow me for more insights and practical advice.
– MDR 2017/745 Article 61, Annex I, Annex XIV
– MDCG 2020-6: Sufficient Clinical Evidence
– FDA Real-World Evidence Framework (2018, updated 2023)
Deepen Your Knowledge
Read Complete Guide to Clinical Evaluation under EU MDR for a comprehensive overview of clinical evaluation under EU MDR 2017/745.
