MDD-to-MDR Clinical Evaluation Gap Analysis: What Legacy CERs Are Missing

Why your existing CER is probably not enough

Most MDD-era Clinical Evaluation Reports were written to a standard that made sense at the time: a literature search, some clinical data from the device's history, an equivalence claim if the clinical data was thin, and a summary conclusion. Under MDR and MEDDEV 2.7/1 rev. 4, none of that is wrong exactly — but the depth required has changed substantially, and the assumptions that underpinned many MDD CERs no longer hold.

The most common scenario we see is a CER that was written once, possibly before the device was even on the market, and has not been meaningfully updated since. It might reference studies from the early 2000s. The state of the art section may be outdated by years. The equivalence claim may have been drafted without the access to technical documentation that MDR now requires. And the PMCF section — if there is one — may amount to a single paragraph saying post-market follow-up will be conducted.

This is not necessarily a compliance failure under MDD. But it is a gap that your Notified Body will flag in the first round of MDR review, and closing it takes longer than most teams expect.

The state of the art and clinical background gap

MDR requires the CER to include a thorough review of the current state of the art — not just what was known at the time of the last update, but what the current evidence base looks like for the clinical condition your device addresses, the therapeutic options available, and where your device sits in that landscape. Many MDD CERs include a literature section that was adequate for its time but has not been updated to reflect studies published in the intervening years.

Closing this gap means running a systematic literature search with a documented methodology — search strings, databases, date ranges, inclusion/exclusion criteria, and a PRISMA-style summary of what was found and what was included. This is more than a literature review; it is a documented process that a reviewer can audit. If your CER was not written this way, the methodology section needs to be rebuilt, not just updated.

The equivalence claim problem

The equivalence route under MDR (Article 61(5) and (6)) is substantially more demanding than it was under MDD. To claim equivalence, you need to demonstrate equivalence in three dimensions — technical, biological, and clinical — and the standard for "sufficient similarity" is stricter. But the part that changes things most is access to technical documentation: for devices not manufactured by your own company, you now need a formal contract with the manufacturer giving you access to their technical file. Without that contract, the equivalence claim is not valid under MDR.

This catches a lot of teams off guard, particularly those whose MDD CER relied on equivalence to a competitor's device. That path is now effectively closed unless you can negotiate document access — which most competitors are not willing to grant. If your MDD CER relies on equivalence to a third-party device, you need to assess whether that equivalence claim can be restructured (using your own device's own data) or whether you need to generate new clinical data to support the MDR CER.

The PMCF gap

Post-Market Clinical Follow-up under MDR is not optional and cannot be satisfied by a boilerplate statement. Your CER needs a PMCF plan that explains what clinical questions remain open, how you will answer them (registry participation, PMCF studies, systematic literature updates, patient-reported outcomes), at what intervals, and what the threshold for PMCF action would be.

If your existing PMCF plan says "we will conduct a PMCF study if indicated by post-market surveillance data," your Notified Body will ask what studies are underway, on what timeline, and what the current data shows. If the answer is "nothing specific is underway," you have a gap. PMCF under MDR means active, structured follow-up — not surveillance data monitoring that might eventually trigger a study.

The benefit-risk conclusion gap

MDR requires the clinical evaluation to reach a clear benefit-risk conclusion based on the clinical data — not just a statement that the device is safe and performs as intended. The conclusion needs to be grounded in specific data points: what the evidence shows about clinical benefit, what the residual risks are, how those risks compare to the current state of the art and available alternatives, and why the benefit-risk balance is acceptable.

If your MDD CER conclusion section is one or two paragraphs asserting that the device is safe and effective, it needs to be rebuilt. This is not just a cosmetic update — it is the part of the CER that carries the weight of the entire clinical case, and it is the section your Notified Body clinical reviewer will spend the most time on.

A realistic approach to gap closure

Start by reading your current CER against the MEDDEV 2.7/1 rev. 4 checklist. Be honest about what is actually present and what is at an acceptable depth — not just what sections exist. The gaps in most MDD CERs cluster in the same places: state of the art currency, equivalence documentation, PMCF specificity, and benefit-risk reasoning. Prioritise these in your CER update plan.

Closing a CER gap for a complex device typically takes three to six months of focused work for an experienced clinical evaluator. Devices that relied heavily on equivalence claims take longer because the equivalence reassessment has to happen first, and if equivalence is not available, a PMCF study design and initiation adds more time. Build this into your transition timeline early — not as the last step before your Notified Body submission.