Following the publication of the MEDDEV 2.7-1 in 2016 rev 4 and subsequently Medical Device Regulation 2017/745 (MDR), medical device manufacturers have been wondering if their existing clinical data is sufficient to comply with the new requirements. Currently, Medical Devices Directive 93/42/EEC (MDD) and Active Implantable Medical Devices Directive 90/385/EEC (AIMDD) certificates are still valid. However, the clock is ticking as these certificates have a limited lifetime (26 May 2024). Thus, manufacturers of medical devices CE-marked under the MDD should evaluate if their existing clinical evidence will stand an MDR Notified Body audit.
To further clarify the requirements on clinical evidence for previously marketed devices, the Medical Device Coordinating Group published a guidance document (MDCG 2020-6 Clinical evidence needed for medical devices previously CE marked). This document includes a new definition for legacy devices and more clarification on what constitutes Well-Established Technology (WET). In this article, we will summarise the key points of MDCG 2020-6.
Legacy devices
The term “legacy device” is not explicitly mentioned in the MDR or in the MEDDEV 2.7-1 rev 4 (the guidance document to prepare clinical evaluations). Nevertheless, the term is implicitly used to describe devices that already have CE marking and have generally been on the EU market for a while under the previous directives (MDD and AIMDD). MDCG2020-6now clearly defines legacy devices as “all devices previously CE marked under the MDD or AIMDD”.
WET
In contrast to legacy devices, WET is a terminology used in MDR but for which a definition is not provided. MDCG 2020-6 adds more clarity and defines WET as medical devices meeting the following criteria:

Therefore, devices that meet these criteria may be considered WET. Some examples of WET mentioned in the MDR include sutures, staples, dental fillings and braces, tooth crowns, screws, wedges, plates, wires, pins, clips and connectors.
Is a clinical investigation needed for legacy devices and WET?
According to MDR Article 61, implantable and class III devices, in general, require clinical investigations. However, this requirement does not apply to implantable and class III devices belonging to the WET previously mentioned if their clinical evaluation is based on sufficient clinical evidence.
“For a specific subset of WET, as those described in Article 61(6b), clinical investigations are not deemed to be necessary if the clinical evaluation is based on sufficient clinical data and is in compliance with the relevant CS.” (MDR Article 61, Section 6a)
The same applies to legacy devices: if the clinical evaluation is based on sufficient clinical data and has been prepared in compliance with the product-specific common specification (CS), no clinical investigation is required.
Therefore, the requirements on clinical data applying for general WET are the same ones for legacy devices. The distinction is that the WET is not explicitly required to have had prior certification under the MDD or AIMDD to be exempted from the requirement for clinical investigations that otherwise apply to class III and implantable devices.
How much clinical data is “sufficient” for legacy devices and WET?
Under the MDR, it is now clear that clinical data being leveraged by a manufacturer must be for an equivalent or similar device. However, the clinical evaluation of WET devices can be based on data pertaining to similar devices, but these data may only be used as indirect supportive data during the clinical evaluation and not as pivotal data. Data that are not pivotal, thus not directly demonstrating the safety and clinical performance of the device concerned, can be included in the clinical evaluation for various purposes, as reported by MEDDEV 2.7/1 rev.4. While the MDR does not provide a detailed definition of the parameters for determining equivalence, the guidance document MDCG 2020-5 and MEDDEV 2.7/1 rev 4 have distinctly identified criteria for evaluating an equivalent device to be used as clinical evidence. You can read more on this topic here (https://akrnconsulting.com/mdr-equivalence-clinical-evaluations/).
In terms of clinical data appraisal, MDCG 2020-6 mainly references MEDDEV 2.7/1, rev. 4 and provides recommendations for commonly recognised and validated assessment tools. In this context, it is mentioned that where a manufacturer relies on preclinical data, additional clinical data from Post-Marker Clinical Follow-up (PMCF) may support the device’s safety and performance claims.
For specific WET devices, a lower level of clinical evidence may be justified.
For WET devices characterized by low risk and where there is little evolution in the state of the art, the clinical evaluation can be mainly supported by data coming from Post-Market Surveillance (PMS).
Moreover, in these cases, a quality management system (QMS) should be in place to systematically collect and analyse relevant post-market data, ensuring a favourable safety, performance, and risk-benefit profile of the device.
Although the MDD and AIMDD indicate that data shall be collected in the post-market phase for all devices, in practice, this may not be possible for WET devices. This is particularly the case for WET not associated with safety concerns and/or with no innovation as they are less likely to be the subject of research. For this reason, in some cases, it may be necessary for the manufacturer to undertake PMCF activities to generate new clinical data before MDR certification to enable an evaluation of the safety and clinical performance of a WET device with an evolving state of the art.
In this context, MDCG 2020-6 Appendix III appears useful since it introduces twelve hierarchical levels of clinical evidence that may be used to support the rationale. WET may confirm conformity with the relevant GSPRs via an evaluation of cumulative evidence from additional sources. Reliance solely on complaints and vigilance is not sufficient.
Final remarks
Based on the MDR specifications, it is recommended that manufacturers conduct a gap analysis concerning their available clinical data and collect additional clinical data in case of gaps in certain areas. A clinical investigation (https://akrnconsulting.com/conducting-clinical-investigations-successfully/) is a suitable option but can be very expensive and time-consuming. A systematic review of existing literature (https://akrnconsulting.com/literature-review-mdr/), for example, can be an alternative here. If it is not possible to close all gaps, this inevitably entails a critical examination of the claims, intended purpose, and indication. Aspects that cannot be substantiated with relevant data must be removed or narrowed the indication for use statement and/or intended purpose until supported by clinical evidence, with all the resulting regulatory consequences. Adopting the MDR clinical evaluation requirements remains challenging, but MDCG 2020-6 provides valuable insights to overcome the hurdles.
As part of our regulatory services, AKRN Scientific Consulting SL can assist medical device manufacturers in developing or updating clinical evaluation documentation for legacy devices and WET. In addition, our expert regulatory team can help manufacturers perform a gap analysis with MDD and fulfill MDR-specific requirements to maintain their medical devices on the market.