Classification of medical devices

The risk class is determined by the manufacturer by comparing the intended purpose against a set of classification rules. The intended purpose is defined in MDR Article 2 (12) as "the use for which a device is intended according to the information provided by the manufacturer in the labeling, in the instructions for use, or in marketing or sales material or statements, and as specified by the manufacturer in the clinical evaluation." A similar definition is found in IVDR Article 2 (12).

For medical devices, the classification rules are found in MDR Annex VIII, and for IVD medical devices, in IVDR Annex VIII.

Here are some points to keep in mind when using the rules for determining the risk class:

• The manufacturer is responsible for classifying their own product.

• It is the manufacturer's intended purpose for the device, and not unintended purposes (e.g., off-label use), that determines the class to which the device belongs.

• Medical devices intended for use with other equipment are classified separately.

• Accessories to medical devices are classified separately from the main equipment.

• Software that controls devices or influences the use of medical devices should belong to the same class as the device.

• Software that is independent of other devices should be classified separately.

• If the device is intended for multiple uses, it should be classified based on the use that presents the highest risk.

• If the device can be classified according to multiple rules, the rule that results in the highest risk class applies.

Medical devices are divided into 4 risk classes ranging from low to high risk: Class I, IIa, IIb, and III. The risk class is determined by the manufacturer's intended purpose and the potential risks associated with the use of the device.

The figure below illustrates the relationship between risk class, risk, and the requirement for involving a notified body:

• Class I (Is, Im, and Ir): Low risk associated with use. For Class I devices that needs to be sterilized (Is), has a measuring function (Im), or is reusable surgical instruments (Ir), a notified body must be involved in the conformity assessment of the parts related to sterilization, measuring function, and reusability.

• Class IIa: Moderate risk associated with use. Requires conformity assessment by a notified body.

• Class IIb: Moderate to high risk associated with use. Requires conformity assessment by a notified body.

• Class III: High risk associated with use. Requires conformity assessment by a notified body.

The risk class is determined by the manufacturer by comparing the intended purpose of the device against the 22 classification rules found in MDR Annex VIII. 

The European Commission has prepared a guide with examples of medical device classification, MDCG 2021-24 (see our list of useful links at the bottom of the page).

In vitro diagnostic (IVD) medical devices are classified into four risk classes ranging from low to high risk: Class A, B, C, and D. As with medical devices, the risk class for IVD medical devices is determined by the manufacturer's intended purpose and the potential risks associated with the device's use. For IVD medical devices, the risk of using the device encompasses both the risk to individual patients and the risk to public health.

The figure below illustrates the relationship between risk class, risk, and the requirement for involving a notified body:

• Class A: Low individual risk and low risk to public health. For Class A devices that are placed on the market in a sterile state, a notified body must be involved in the conformity assessment of the components related to sterilization.

• Class B: Moderate individual risk and/or low risk to public health. Requires conformity assessment by a notified body.

• Class C: High individual risk and/or moderate risk to public health. Requires conformity assessment by a notified body.

• Class D: High individual risk and high risk to public health. Requires conformity assessment by a notified body.

The European Commission has prepared a guide with examples of IVD device classification, MDCG 2020-16 (see our list of useful links at the bottom of the page).

The risk class is crucial for determining the procedure to be followed before placing a product on the market, also known as conformity assessment. The risk class will, among other things, determine whether the equipment should be assessed and monitored by a notified body. Learn more about conformity assessment here.