In October 2021, the Medical Device Coordination Group released a guidance document on the classification of medical devices (MDCG 2021-24). The guidance document provides extensive counsel on the 22 rules outlined in Annex VIII of the medical device regulation (EU MDR 2017/745) and helps manufacturers understand the implications of the classification. Using practical examples and graphical summaries, the 57-page document describes the rules and subrules governing noninvasive, invasive, and active medical devices. It also provides a brief overview of how device classification affects the process of conformity assessment, clinical evaluation, and post-market surveillance.
"Some diagnostic device manufacturers may have to ensure compliance with both MDR and IVDR regulations."
Devices are divided into classes I, IIa, IIb, and III, based on the intended purpose of the devices and their inherent risks. The main criteria that define device risk, and by extension its classification, are as follows:
- Duration of contact with the body: Transient use is defined as continuous use for less than 60 minutes; short-term use is continuous use for between 60 minutes and 30 days; long-term use is continuous use for more than 30 days.
- Degree of invasiveness: Whether a device (either wholly or partially) penetrates the body via a natural orifice, injured skin or mucous membrane, or a surgical incision.
- Delivery of energy or pharmaceutical products: Potential toxicity and local versus systemic effects of the energy source or medicinal substances delivered by the device are important considerations.
- Part of the body affected: Use on critical anatomical locations such as the central circulatory system and central nervous system increases device risk.
Classification rules outlined in the EU MDR 2017/745 regulation and further explained in the MDCG 2021-24 guidance document are also applicable to certain diagnostic devices. For example, imaging and radiologic devices, such as magnetic resonance equipment, ultrasound, X-ray, and computed tomography devices, fall under the purview of Rule 10—active devices for diagnosis and monitoring or intended for diagnostic or therapeutic radiology.
Manufacturers of diagnostic devices such as glucose monitors need to pay special attention to rules for devices with a measuring function, as well as their associated accessories and software.
"In case several rules or subrules apply to the same device, the strictest rule and subrule resulting in the highest classification will apply."
Section 3.1.6 of MDCG 2021-24 provides additional guidance for noninvasive devices with a measuring function. Software that monitors physiological processes or informs decisions about diagnosis or therapy are classified in accordance with Rule 11. In case several rules or subrules apply to the same device, the strictest rule and subrule resulting in the highest classification will apply.
EU MDR 2017/745 regulations went into effect on May 26, 2021. The regulations are intended to establish a robust, transparent, and predictable regulatory framework that supports patient safety and technological innovation. A similar regulatory framework is to be implemented for in vitro diagnostic devices with the in vitro diagnostic regulation (IVDR EU 2017/746) being executed on May 26, 2022.
IVDR institutes a rule-based classification system that divides diagnostic devices into class A (low risk) through class D (highest risk). An explanation of the seven classification rules under IVDR is provided in an MDCG guidance document (MDCG 2020-16) published in November 2020. Some diagnostic device manufacturers may have to ensure compliance with both MDR and IVDR regulations.