Risk Classification

Rules-based and predicate-based classification of medical devices

What is risk classification?

Risk classification for medical devices is a systematic process that categorises devices based on the level of risk they pose to patients, operators, and other users.

Once the qualification of a medical device has been determined, its risk classification must be assessed. The classification system helps regulatory authorities and manufacturers determine the appropriate level of regulatory scrutiny and requirements for ensuring the safety and effectiveness of medical devices. Risk classification typically considers factors such as the intended purpose of the device, its mode of action, potential hazards, and the degree of harm associated with device failure or misuse.

Factors that determine the risk classification of medical devices include:

Intended Use

  • Primary Purpose: The specific medical condition or disease the device is designed to diagnose, prevent, monitor, treat, or alleviate.
  • Duration of Use: How long the device is intended to be used (e.g., transient, short-term, long-term).

Degree of Invasiveness

  • Non-invasive: Devices that do not penetrate the body or come into contact with internal organs or tissues.
  • Invasive: Devices that penetrate the body either through an orifice or through the surface of the body.
  • Surgically Invasive: Devices introduced into the body through surgical means are typically considered higher risk.
  • Non-surgically Invasive: Devices such as endoscopes or catheters that enter the body through natural orifices Duration of Contact
  • Transient: Devices that are used for less than 60 minutes.
  • Short-term: Devices that are used for up to 30 days.
  • Long-term: Devices intended for continuous use for more than 30 days.

Body Interaction

  • Surface-contacting: Devices that only contact intact skin or mucous membranes.
  • Externally Communicating: Devices that contact the external surface and enter a body cavity or tissue.
  • Implantable: Devices placed inside the body, such as pacemakers or hip implants.

Energy Source

  • Passive Devices: Devices that do not require a power source are generally considered lower risk.
  • Active Devices: Devices that use electrical or other forms of energy may pose additional risks.

Technological Characteristics

  • Novelty: New or innovative technologies that have not been previously evaluated may be classified as higher risk due to the lack of historical safety data.
  • Complexity: Complex devices with multiple components or software integration may pose higher risks.

Potential for Harm

  • Severity of Harm: The potential severity of harm resulting from device failure or malfunction.
  • Probability of Harm: The likelihood of the device causing harm under normal conditions of use.

Clinical Considerations

  • Patient Population: Special populations such as paediatrics, geriatrics, or individuals with compromised health may influence risk classification.
  • Condition of Use: The clinical setting (e.g., hospital, home use) and the user (e.g., trained healthcare professionals, laypersons) can impact risk assessment.

Previous Experience and Post-market Data

  • Historical Data: Existing safety and performance data from similar devices can influence risk classification.
  • Post-market Surveillance: Data from real-world use and adverse event reports contribute to understanding risks.

Rules-based and predicate-based risk classification systems

Rules-based risk classification and predicate-based risk classification are two approaches used to classify medical devices based on their risk levels. These approaches are typically associated with regulatory systems and are used to determine medical device regulatory requirements and pathways.

The primary difference between the two approaches is the basis for classification. Rules-based classification relies on predefined criteria and is not tied to the existence of a predicate device. In contrast, predicate-based classification relies on comparing to an existing, previously approved device (predicate).

    A rules-based risk classification is an approach in which medical devices are classified into different risk categories based on predefined rules and criteria set forth by the regulatory authority.

    Under this method, the regulatory authority establishes specific criteria and rules that consider factors such as the intended use, potential risks to patients and users, duration of contact with the body, and other device-specific characteristics.

    Rules-based classification is not reliant on the classification of similar devices or the existence of predicate devices. It is determined based on objective and predefined criteria.

    Rules-based risk classification is commonly used in regulatory systems where the classification of a medical device is primarily determined by its inherent characteristics and intended use. For example, the European Union’s Medical Devices Regulation (MDR) uses a rules-based approach to classify medical devices into different risk classes (Class I, IIa, IIb, and III).

    Rules-based classification tends to be more objective and is often used when there is no suitable predicate or when a regulatory authority wants to establish classification based on inherent risk factors.

    Predicate-based risk classification is an approach in which the classification of a medical device is determined based on its similarity to existing devices that have already been classified and approved by the regulatory authority. In this approach, a new device is classified based on its likeness or equivalence to a previously approved device, known as the predicate.

    Predicate-based classification relies on the existence of a suitable predicate device that has already undergone regulatory approval. The new device is compared to the predicate regarding intended use, technological characteristics, and risk profile.

    This approach is used in regulatory systems like the U.S. Food and Drug Administration (FDA) for medical devices, where the 510(k) premarket notification process allows manufacturers to demonstrate substantial equivalence to a predicate device to gain market clearance.

    Predicate-based classification is common in systems where substantial equivalence to a predicate is accepted as a pathway for regulatory clearance. It is often used for devices with lower risk profiles and well-established technology.

    Common risk classification systems

    Manufacturers should know the specific regulatory requirements in the region where they intend to market their medical devices and follow the applicable classification approach for their products.

    • European Union: The EU Medical Device Regulation (MDR) uses rules-based risk classification to classify devices into four categories: Class I, Class IIa, Class IIb, and Class III, with Class I being the lowest risk and Class III being the highest risk.
    • United States: The FDA uses predicated-based risk classification to classify devices into three classes: Class I (general controls), Class II (special controls), and Class III (premarket approval), with Class I being the lowest risk and Class III being the highest risk.
    • Global Harmonisation Task Force (GHTF) / IMDRF: Provides guidelines for classifying medical devices based on their intended use and the potential risks associated with their use.

    Why is risk classification important?

    Determining Regulatory Pathways

    • Approval Process: a medical device’s risk classification determines the regulatory scrutiny it will undergo before it can be marketed. Higher-risk devices require more extensive testing, clinical trials, and review processes than lower-risk devices.
    • Conformity Assessment: The classification influences the type of conformity assessment procedures that need to be followed, which may involve different levels of involvement from notified bodies or regulatory authorities.

    Ensuring Patient Safety

    • Risk Management: By categorising devices based on risk, regulatory bodies can ensure that higher-risk devices, which have greater potential to harm patients if they fail or malfunction, are subject to more stringent requirements. This helps to mitigate potential risks associated with their use.
    • Post-Market Surveillance: Higher-risk devices are often subject to more rigorous post-market surveillance activities, including adverse event reporting and periodic safety updates.

    Guiding Manufacturers

    • Design and Development: Risk classification guides manufacturers in designing and developing medical devices. It helps them understand the regulatory requirements they must meet, including the level of evidence needed to demonstrate safety and efficacy.
    • Labelling and Instructions: The classification affects the labelling and instructions for use (IFU) that must accompany the device. Higher-risk devices require more detailed information to ensure proper usage and to inform users about potential risks.
    • Training and Support: Healthcare professionals and patients may require additional training and support when using higher-risk devices. This ensures that they are used safely and effectively.

    Resource Allocation

    • Regulatory Resources: Regulatory authorities can allocate their resources more efficiently by focusing on higher-risk devices that require more oversight and monitoring. This ensures that critical resources are directed towards areas with the greatest potential impact on patient safety.
    • Inspection and Audits: Authorities can prioritise inspections and audits based on devices’ risk classification, ensuring that higher-risk devices receive more frequent and thorough inspections.

    Resources

      MedDev Central Academy:

      MedDev Central Knowledge Hub:

      European Union (EU):

      Medical Device Coordination Group (MDCG) guidance documents on medical device classification:

      United States of America (USA):

      Food and Drug Administration (FDA) guidance documents:

      Australia:

      Therapeutic Goods Administration (TGA) classification guidance:

      China:

      National Medical Products Administration (NMPA) guidance in English:

      European Union (EU):

      Medical Devices Regulation (MDR) 2017/745:

      In Vitro Diagnostic Medical Devices Regulation (IVDR) 2017/746

      United States of America (USA):

      Food and Drug Administration (FDA), Federal Food, Drug, and Cosmetic Act (FD&C Act):

      Classification: The process of categorising devices into different classes based on their intended use, level of risk to patients and users, and regulatory controls necessary to ensure safety and effectiveness.

      Clinical Context: The specific medical conditions, patient populations, and healthcare settings in which a device is intended to be used, influencing its design, functionality, and regulatory requirements.

      Equivalency: Demonstrating that a new device is as safe and effective as an already marketed device by comparing its technical and functional characteristics.

      Indication of Use: A concise statement specifying the medical conditions or purposes for which the medical device is intended to be used, as approved by regulatory authorities.

      Instructions for Use (IFU): The document provided by the manufacturer that includes essential information on a medical device’s intended purpose, proper handling, operation, maintenance, and safety precautions for users.

      Intended purpose: The use for which a medical device is intended according to the information provided by the manufacturer on the labelling, in the instructions for use (IFU), or in promotional materials. This may also be referred to as the Intended Use in some jurisdictions. Also see Indication of Use.

      Labelling: The label on a medical device and all descriptive and informational literature associated with the device. Also see Instructions for Use (IFU)

      Manufacturer: A legal entity that designs, produces, assembles, or labels a medical device with the intention of placing it on the market.

      Mode of Action: The means by which a device achieves its intended therapeutic or diagnostic effect.

      Qualification: The process of determining whether a product meets the definition of a medical device in a particular jurisdiction.

      Predicate Device: An existing on-market device that provides a basis for comparison or reference in demonstrating substantial equivalence for regulatory purposes.

      Regulation: The rules, laws, standards, and requirements set by regulatory authorities to ensure the safety, efficacy, and quality of devices intended for medical use.

      Regulatory Authority: An official body overseeing and enforcing laws, regulations, and standards within a specific industry or sector to ensure compliance and protect public interests. Also known as a Regulatory Authority. Also see Competent Authority and Notified Body.

      Regulatory Submission: The formal process of submitting documentation and data to regulatory authorities for review and approval to market or sell the device within a specific jurisdiction.

      Standard: A document that provides guidance, requirements, or specifications established by regulatory bodies, industry organisations, or international consensus groups.

      Technical Documentation: All documents that demonstrate the design, manufacture, and performance of the device, essential for ensuring compliance with regulatory requirements. This is also known as the Technical File.

      Updated on 29 May 2024