Understanding the Classification of Medical Devices under EU MDR

Class I: This group includes low-risk devices like non-invasive devices, such as hospital beds or bandages, or invasive tools used only transiently in body orifices, such as dental impression materials. Class I devices can be active, such as examination lamps.

For many Class I devices, the declaration of conformity does not require third party assessment by a notified body. Examples include medical gloves and tongue depressors.

However, the MDCG 2021-24 Guidance on the classification of medical devices specifies three subclasses of Class I devices that do require third-party assessment by a Notified Body:

- Class Ir (Reusable Surgical Instruments): These devices (instruments) are intended to be used multiple times after appropriate procedures for cleaning and sterilization. A notified body is required to assess aspects relating to the reuse of the device, in particular cleaning, disinfection, sterilization, maintenance and functional testing and the related instructions for use. Forceps or scalpels are an example of this subclass

- Class Is (Devices placed on the market in a sterile condition): These devices are sold and delivered in sterile condition. A notified body is required to assess the aspects relating to establishing, securing and maintaining the sterile condition. An Example would be sterile bandage or a sterile syringe.

- Class Im (Devices with a measuring function): Any Class I device with a measuring function must provide accurate measurement results. A notified body is required to assess aspects relating to the metrological requirements. Examples include expansion thermometers and measuring cups.

Class IIa: Devices of this category pose a medium risk, for example, short term corrective contact lenses, feeding pumps, and polymer film wound dressings. For devices of class IIa, a conformity assessment conducted by a notified body will ensure they meet all regulatory criteria. This procedure includes the assessment of a technical documentation, including a clinical evaluation assessment, which are described later in this article.

Class IIb: Devices of the class IIb pose a higher risk then Class IIa, so more data and analysis is required to demonstrate their performance and safety. As a result, the notified body conformity assessment procedure takes longer and, by the nature of the device, can involve more experts, including clinical experts. Typical examples for this class are devices that are used for longer time periods, such as long-term corrective contact lenses and urinary catheters, devices with critical functions, such as lung ventilators or infusion pumps, and devices that emit radiation, such as therapeutic X-ray sources.

Class III: Such Devices are the highest-risk devices and include life-sustaining implants and medication delivery systems. Examples include are heart valves, pacemakers, or drug-eluting stents. Class III must meet the strictest regulatory requirements to ensure patients and users are as safe as possible.

In addition to requiring more evidence for initial certification, the MDR requirements related to post market surveillance, risk management and clinical evaluations increase with the risk classification.

Conformity Assessment

As mentioned above, whereas Class I devices, manufacturers can self-assess conformity to the requirements. On the other hand, devices in Class Ir, Im, Is, IIa, IIb, and III require third party conformity assessment by a Notified Body to confirm that the manufacturer’s declaration of conformity complies with the MDR requirements. The conformity assessment considers the results of testing according to applicable standards to the device to generate objective evidence that proves that the device meets applicable safety and performance requirements. The manufacturer also presents clinical data integrated into post-market surveillance and risk management to demonstrate a positive benefit-risk ratio for the patients and users. Where requirements are met, the manufacturer can make a legally-binding declaration of conformity and place CE marking on their devices.

Technical Documentation

The data for conformity assessment includes technical documentation. This obligatory and essential tool includes, but is not limited to, a detailed description of the device's design, the materials used, the intended purpose, results of performed tests, biocompatibility, clinical evaluation and market surveillance. Technical documentation is required whether the manufacturer self-declares a Class I device or instructs a notified body to perform conformity assessment.

Manufacturers must make available up-to-date technical documentation to the EU Competent Authorities to assess the safety and performance of the device. For manufacturers located outside the EU, this documentation must be lodged with and retained by their Authorised Representative.

Clinical Evaluation and Post-Market Surveillance

Clinical evaluation and post-market surveillance is required for all medical devices, regardless of risk classification, although the requirements increase with increasing risk class. The clinical evaluation presents evidence and conclusions that demonstrate the safety and performance of the medical devices. Post-market surveillance systems are required for all devices to monitor real-world performance, gather user feedback, and document adverse events. All devices other than Class I devices need follow-up studies and Periodic Safety Update Reports (PSURs); the level of data required and frequency of these reports increases with the risk class.

Instructions and labels

Medical device manufacturers must meet specific labelling requirements defined in the MDR and including basic information such as product specifications, intended purpose, important precautions, and any contraindications or warnings that helps users understand how to use the device safely and effectively, thereby reducing the risk of misuse and potential accidents.