To make it easier to classify medical devices, they are differentiated into various categories. As in the Medical Device Directive (MDD), they are divided into three classes for this purpose in the Medical Device Regulation (MDR). Thus, how a product is evaluated to reach the market also differs, as there are significantly different requirements for a plaster than for an artificial knee joint.

EU’s updated regulation uses a system that evaluates the risk of each product. The lower the risk to users, the lower the MDR class. Depending on the product classes, conformity assessment procedures must also be applied. In this new article, we explain their respective relation to the MDR classes

MDR Classes

For overview purposes, we listed the medical device classes in a table for you. The categories used are classification, definition, examples, and certification. Certification here stands for the need for certification by a Notified Body. Current transition periods of the MDR of Legacy Devices.

Medical Devices of Class I

Transition Period: Dec 31, 2028

• Devices of MDR Class I carry a low risk and are mostly non-invasive devices with no effects on the human body.
• There is no or non-critical skin contact and the application is only temporary of less than 60 minutes.

Classification	Definition	Examples	Certification
Class I	Devices that are not sterile or do not have a measuring function	wheelchairs, bandaids, hospital beds, bedpans, walking aids, support stockings	No
Class Is	Products that are marketed in a sterile condition	personal protective equipment, surgical textiles	Partially
Class Im	Devices that feature a measuring function	stethoscopes, thermometers, scales	Partially
Class Ir	Products that are reprocessed or reused	surgical instruments, endoscopes	Partially

Medical Devices of Class II

Transition Period: Dec 31, 2027 | IIb implantable, Dec 31, 2028 | IIa + IIb non-implantable

• Devices of MDR Class IIa carry a medium risk and are generally invasive, but they are limited to natural body openings.
• Devices of MDR Class IIb carry a medium to high risk and include surgically invasive or active devices that are partially or fully inserted into the body.

Classification	Definition	Examples	Certification
Class IIa	Short-term application in the body (60 minutes to 30 days)	dental materials, disinfectants for instruments & equipment, dental crowns, tracheal tubes, PACS, diagnostic ultrasound devices, disposable syringe, hearing aids, contact lenses	Yes
Class IIb	Long-term application in the body (More than 30 days)	anesthesia equipment, ventilators, radiation equipment, blood bags, defibrillators, apheresis equipment, dialysis devices, condoms, dental implants, medical gas systems, contact lens cleaning solution, automated cleaning disinfection machines, infusion devices	Yes

Medical Devices of Class III

Transition period: Dec 31, 2027

Classification	Definition	Examples	Certification
Class III	Devices that are inserted into the central circulatory or nervous system for long-term treatment or contain medications	cardiac catheter, artificial hip, knee or shoulder joint, stent, breast implant, resorbable surgical suture, intrauterine device, hormonal coil	Yes

Software as a Medical Device

A lot of medical devices use software, be it pacemakers, ventilators, or the image processing of X-ray devices. Typically these are embedded into the device they are used in. However, there are also softwares that pose as medical devices themselves. They are called Stand-alone SaMD (software as a medical device). The classification of embedded and stand-alone SaMDs is layed out in Rule 11 of Annex VII of the MDR:

Software intended to provide information which is used to take decisions with diagnosis or therapeutic purposes is classified as class IIa, except if such decisions have an impact that may cause:

• death or an irreversible deterioration of a person’s state of health, in which case it is in class III; or
• a serious deterioration of a person’s state of health or a surgical intervention, in which case it is classified as class IIb.

Software intended to monitor physiological processes is classified as class IIa, except if it is intended for monitoring of vital physiological parameters, where the nature of variations of those parameters is such that it could result in immediate danger to the patient, in which case it is classified as class IIb.

All other software is classified as class I.

Conformity Assessment

During conformity assessment, it is determined whether the medical device in question meets the requirements of the MDR. Manufacturers are responsible for conformity, while the Notified Bodies usually perform the final assessment of the products. Here, the higher the product class, the more the Notified Bodies are involved. There are three conformity assessment procedures:

• Conformity assessment based on a quality management system and an evaluation of the technical documentation.
• Conformity assessment based on a type-examination
• Conformity assessment based on a product conformity verification

Conformity Assessment by Classes

As mentioned, the conformity assessment depends on the MDR class. We present here which procedure applies to which class:

• Class I: Products must have technical documentation. Manufacturers then issue an EU declaration of conformity, thereby ensuring the conformity of their product.
• Class II: In this class, conformity is ensured based on the quality management system and technical documentation. For implantable devices in Class IIb, it is also necessary to provide the technical documentation for each product. (This excludes sutures, staples, dental fillings, dental braces, tooth crowns, screws, wedges, plates, wires, pins, clips, and connectors).
• Class III: For the conformity of this class, either the quality management system can serve or the type-examination in combination with the production conformity examination. However, custom-made products are excluded here.

[Disclaimer]

This information is only one possible interpretation of the regulations. They are also in a constant state of change, so the information in this article may be incomplete or out of date. The above article is expressly no legal advice. Please refer to the official documents for information before making any business decisions. (Status of information: January 2023, update of transition deadlines November 2023 )