Understanding MDR Classification
The EU Medical Device Regulation (MDR) 2017/745 classifies medical devices into four risk-based categories: Class I, Class IIa, Class IIb, and Class III. Classification is determined by the intended purpose of the device, its mode of action, the duration of use, and the degree of invasiveness into the human body. These rules are set out in Annex VIII of the regulation and consist of 22 classification rules organized across several categories.
Accurate classification is critical because it directly determines the conformity assessment procedure that a manufacturer must follow, the level of Notified Body involvement required, and the extent of clinical evidence that must be provided.
The Four Device Classes
Class I — Low Risk
Class I devices present the lowest risk to patients and users. Examples include bandages, non-powered wheelchairs, tongue depressors, and reusable surgical instruments (Class Ir). Most Class I devices do not require Notified Body involvement; however, sterile Class I devices (Class Is), devices with a measuring function (Class Im), and reusable surgical instruments (Class Ir) do require limited Notified Body assessment for those specific aspects.
Class IIa — Medium Risk
Class IIa devices represent a moderate level of risk. Examples include hearing aids, blood transfusion equipment, surgical gloves, and short-term surgically invasive devices. These devices require conformity assessment by a Notified Body, which includes evaluation of technical documentation and quality management system auditing.
Class IIb — Medium-High Risk
Class IIb devices carry a higher level of risk. Examples include ventilators, bone fixation plates, intensive care monitoring equipment, and condoms. These devices require a more extensive conformity assessment, with thorough review of clinical evidence and a full quality management system audit. Notified Body involvement is mandatory.
Class III — High Risk
Class III devices represent the highest risk to patients. Examples include cardiac pacemakers, hip replacement implants, coronary stents, breast implants, and spinal disc replacements. These devices are subject to the most rigorous conformity assessment procedures, including scrutiny procedures involving expert panels in certain cases. Full Notified Body assessment of both technical documentation and the quality management system is required.
MDR Classification Rules
Annex VIII of the MDR defines 22 classification rules, organized into the following groups:
- Rules 1–4: Non-invasive devices — classified based on contact with body fluids, modification of biological composition, and contact with injured skin.
- Rules 5–8: Invasive devices — classified by whether they are surgically invasive or enter body orifices, duration of use (transient, short-term, long-term), and connection to active devices.
- Rules 9–13: Active devices — classified based on therapeutic function, diagnostic function, delivery or exchange of energy, and monitoring of vital physiological parameters.
- Rules 14–22: Special rules — covering devices incorporating medicinal substances, devices for contraception, disinfection of medical devices, devices utilizing nanomaterials, and software as a medical device (SaMD).
Rule 11 is particularly significant as it governs software intended to provide information used for diagnostic or therapeutic decisions. Under MDR, standalone medical software has been reclassified into higher risk categories compared to the former Medical Device Directive (MDD).
How to Determine Your Device Class
- Define the Intended Purpose: Clearly establish the device's intended use, target patient population, medical indication, and any contraindications. The intended purpose is the primary driver of classification.
- Identify Applicable Classification Rules: Review the 22 rules in Annex VIII and identify all rules that apply to your device. A single device may fall under multiple rules.
- Apply the Highest Classification: When multiple rules apply, the highest resulting classification takes precedence. This ensures the most protective conformity assessment route is followed.
- Document the Rationale: Record the classification rationale in your technical documentation, including identification of the rules applied and justification for the determined class.
- Engage the Notified Body: For Class IIa, IIb, and III devices, engage a Notified Body to confirm the classification and initiate the appropriate conformity assessment.
Implications of Classification
The device classification directly impacts the manufacturer's regulatory obligations:
- Conformity Assessment Route: Higher-class devices require more extensive Notified Body assessment, including full technical documentation review and QMS audit.
- Clinical Evidence: Class III and implantable devices are subject to the most stringent clinical evidence requirements, including post-market clinical follow-up (PMCF).
- Post-Market Surveillance: Higher-risk devices require periodic safety update reports (PSURs), while Class III and implantable devices must produce annual PSURs.
- Expert Panel Scrutiny: Certain Class III and Class IIb devices may require clinical evaluation consultation by an expert panel before certification.
Changes from MDD to MDR Classification
The transition from the Medical Device Directive (MDD) to MDR introduced significant classification changes. Many devices have been reclassified into higher risk categories. Notable changes include:
- Software as a Medical Device (SaMD) is now classified based on clinical impact, often resulting in Class IIa or higher classification.
- Devices incorporating nanomaterials are subject to specific classification considerations under Rule 19.
- Devices intended for cleaning, disinfection, or sterilization of other medical devices are classified under Rule 16.
- Reusable surgical instruments are now classified as Class Ir and require Notified Body involvement for reprocessing validation.
If you are uncertain about your device's classification under MDR, contact Udem Atlantic to discuss your specific device and receive guidance on the applicable conformity assessment route.