Contributor: Sana Shaikh
In this article
- Overview of medical device categorisations and classifications for regulatory purposes in the United Kingdom
- Summary of medical devices categorisations based on type, usage and risk potential during use as specified in the MDR and IVDR.
- The class of medical device and its purpose determines the criteria required to meet regulatory approval. All medical devices in the UK must have a UKCA or CE marking depending on the legislation the device has been certified under.
- Explanation of risk classifications for general medical devices and active implantable devices
- Explanation of risk classifications for in vitro diagnostics
In the UK and EU medical devices are regulated under the Medical Devices Regulation (MDR) or In Vitro Diagnostics Regulation (IVDR) depending upon which category they fall under. In the UK it is the Medicines and Healthcare Products Regulatory Agency (MHRA) that is responsible for new product approval and market surveillance activities related to medical devices and other therapeutics, such as pharmaceuticals, intended for use in patients within the UK. The equivalent regulatory agency in the EU is the European Regulatory Agency (EMA). The MHRA also manages the Early Access to Medicines Scheme (EAMS) to enable patients access to pre-market therapeutics that are yet to receive regulatory approval where their medical needs are currently unmet by existing options. To qualify for EAMS a medicine must be designated as a Promising Innovative Medicine (PIM) based on early clinical data.
Having a thorough understanding of the classification and class of your medical device is vital for it to undergo the appropriate assessment route and be approved and ready for market. While the scope of medical devices is incredibly broad, for regulatory purposes they tend to be classified based on device type, duration of use and level of risk. Which risk class a device falls into will be determined in a large part by device type and duration of use, as both of these factors influence the level of risk to the patient. All medical devices in the UK must be designated a category and a risk classification in order to undertake the regulatory approval process.
Category (type) of Medical Device
The MHRA categorises medical devices into the following 5 categories:
- Non-invasive – Devices which do not enter the body
- Invasive – Devices which in whole or part are inserted into the body’s orifices (including the external eyeball surface) or through the surface or the body such as the skin.
- Surgically invasive – Devices used or inserted surgically that penetrate the body through the surface of the body, such as through the skin.
- Active – Devices requiring an external source of power, including stand-alone software.
- Implantable – Devices intended to be totally or partially introduced into the human body (including to replace an epithelial surface or the surface of the eye) by surgical intervention and to remain in place for a period of time.
Duration of use category
Medical devices are then further categorised based upon their intended duration of use under normal circumstances.
- Transient – intended for less than 60 minutes of continuous use.
- Short term – intended for between 60 minutes to 30 days of continuous use.
- Long term – intended for more than 30 days continuous use.
More information to aid accurate medical device categorisation in the UK and EU can be downloaded here: Medical devices: how to comply with the legal requirements in Great Britain – GOV.UK (www.gov.uk)
UKCA Mark & Conformity Assessment
Further to these use, duration and risk categories the HPRA designates 3 additional categories for the purposes of UKCA Mark and conformity assessment. These categories for the are:
- General medical devices – most medical devices fall into this category.
- Active implantable devices – devices powered by implants or partial implants intended to remain in the human body after a procedure.
- In vitro diagnostics medical devices (IVDs) – equipment or system used in vitro to examine specimens from the human body.
UKCA mark and conformity assessment and subsequent labelling is a crucial procedure for a device to enter the UK market for use by patients. It should be noted that the UKCA mark is not recognised in the EU or Northern Ireland, who instead recognise the CE mark. Great Britain will not recognise the CE mark after 30 June 2023, thus it will be important to have both the UKCA and CE mark for widespread distribution of a medical device. These incompatibilities seem to have arisen largely as a result of Brexit.
Risk classification categories for general medical devices and active implantable devices
In The UK and EU there are 4 official risk-related classes for medical devices. These classes apply to both general medical devices and active implantable devices. As noted previously, the class a device falls into is largely informed by the category and the intended duration of use for the device.
- Class I , which includes the subclasses Class Is (sterile no measuring function), Class Im (measuring function), and Class Ir (devices to be reprocessed or reused). Low risk of illness/injury resulting from use. Only self-assessment required to meet regulatory approval.
- Class IIa Low to medium risk of illness/injury resulting from use. Notified Body approval required.
- Class IIb Medium to high risk of illness/injury resulting from use. Notified Body approval required.
- Class III high potential risk of illness/injury resulting from use. Notified Body approval required.
More details on these classes can be found below.
In Vitro Diagnostic Medical Devices (IVDs)
The IVDR categorise IVDs in to the following categories for the purpose of obtaining regulatory approval in Great Britain. IVDs do not harm patients directly in the same way that other medical devices can and are thus subject to different risk assessment.
- General IVD medical devices
- IVDs for self-testing – intended to be using by an individual at home.
- IVDs stated in Part IV of the UK MDR 2002, Annex II List B
- IVDs stated in Part IV of the UK MDR 2002, Annex II List A
A more detailed explanation of these categories can be found towards the end of this article.
The EU and Northern Ireland has moved away from this list style of classification and has recently implemented the following risk classes. There are 4 IVDR risk classes outlined in Annex VIII. It seems likely that Great Britain may follow this in future.
Risk Classes for IVDs
- Class A – Laboratory devices, instruments and receptacles.
- Class B – All devices not covered in the other classes.
- Class C – High risk devices presenting a lower direct risk to the patient population. Includes diagnostic devices where failure to accurately diagnose could be life-threatening. Covers companion diagnostics, genetic screening and some self-testing.
- Class D – Devices that pose a high direct risk to the patient population, and in some cases the wider population, relating to life threatening conditions, transmissible agents in blood, biological materials for transplantation in to the human body and other similar materials.
Risk categories for general medical devices and active implantable medical devices in detail
Class I devices
These are generally regarded as low risk devices and pose little risk of illness and injury. Such devices have minimal contact with patients and the lowest impact on patient health outcomes. To self-certify your product, you must confirm that it is a class I device1,3. This may involve carrying out clinical evaluations, notifying the Medicines and Healthcare products Regulatory Agency (MHRA) of proposals to perform clinical investigations, preparing technical documentation and drawing up a declaration of conformity1. In cases where the device includes sterile products or measuring functions, approval from a UK Approved Body may still be necessary3. Devices in this category include thermometers, stethoscopes, bandages and surgical masks.
Class IIa & IIb devices
Class IIa devices are generally regarded as medium risk devices and pose moderate risk of illness and injury. Both class IIa and IIb devices must be declared as such by applying to a UK Approved Body and performing a conformity assessment3, 4. For class IIa and IIb devices, there are several assessments. These include examining and testing the product or a homogenous batch of products, auditing the production quality assurance system, auditing the final inspection and testing or auditing the full quality assurance system3. include dental fillings, surgical clamps and tracheotomy tubes4 Class IIb devices include lung ventilators and bone fixation plates4.
Class III devices
These are considered high risk devices and pose substantial risk of illness and injury. Devices in this category are essential for sustaining human life and Due to the high-risk associated with class III devices, they are subject to the strictest regulations. In addition to the class IIa and IIb assessments, class III devices require a design dossier examination3. include pacemakers, ventilators, drug-coated stents and spinal disc cages.
Risk Categories for In Vitro Diagnostics in detail
These include but are not limited to reagents, instruments, software and systems intended for in vitro examination of specimens such as tissue donations and blood4. Most IVDs do not require intervention from a UK Approved Body5. However, for IVDs that are considered essential to health, involvement of a UK Approved Body is necessary5. The specific conformity assessment procedure depends on the category of IVD concerned5.
These are considered a low risk to patients and include clinical chemistry analysers, specimen receptacles and prepared selective culture media4. For general IVDs, involvement from a UK Approved Body is not required5. Instead, relevant provisions in the UK MDR 2002 must be met and self-declared prior to adding a UKCA mark to the device5,6.
IVDs for self-testing
These represent a low-to-medium risk to patients and include pregnancy self-testing, urine test strips and cholesterol self-testing4. In addition to conforming to requirements for general IVDs, applications for IVDs involved in self-testing must be sent to a UK Approved Body5. This enables examination of the design of the device, such as how suitable it is for non-professional users5.
IVDs stated in Part IV of the UK MDR 2002, Annex II List B
These represent medium-to-high risk to patients and include blood glucose self-testing, PSA screening and HLA typing4. Applications for devices in this category must be sent to a UK Approved Body5. This can enable auditing of technical documentation and the quality management system6.
IVDs stated in Part IV of the UK MDR 2002, Annex II List A.
These represent the highest risk to patients and include Hepatitis B blood-donor screening, ABO blood grouping and HIV blood diagnostic tests4. Due to the high risk associated with IVDs in this category, applications for devices in this category must be sent to a UK Approved Body5. By doing so, an audit of the quality management system can be performed as well as a design dossier review6. In addition, the UK Approved Body must verify each product or batch of products prior to being placed on the market5,6.
Proposed updates to medical device categories in the UK
Due to the quickly evolving state of medical technology, many items that did not previously count as a medical device, such as software and AI, are now needing to be considered as such. New proposals have been put forward as potential amendments to the existing regulations and risk classifications to accommodate newer technologies and devices. Among other proposed changes the following list of novel devices has been recommended for upgrade to the classification of highest risk Class III.
- Active implantable medical devices and their accessories
- in vitro fertilisation (IVF) and Assisted reproduction technologies (ART)
- Surgical meshes
- total or partial joint replacements
- spinal disc replacements and other medical devices that come into contact with the spinal column
- medical devices containing nano-materials
- medical devices containing substances that will be introduced to the human body by one of various methods of absorption in order to achieve their intended function.
- Active therapeutic devices with an integrated diagnostic function determining patient management such as closed loop or automated systems.
With the shift to a higher risk classification will come increased demand of clinical evidence and clinical testing, including clinical trials, in order for these devices to meet regulatory approval and reach the market. While an increased burden for the manufacturer this will be to the benefit patient safety and satisfaction for the end users. A full list of the proposed changes, including those outside of Class III, can be found here: Chapter 2: Classification – GOV.UK (www.gov.uk)
Medical devices are incredibly heterogenous, ranging from therapeutics and surgical tools to diagnostics and medical imaging software including machine learning and AI. Accordingly, medical device research and development often requires an interdisciplinary approach. During R&D, it is important to consider for whom the device is intended, how it will be used, and under what circumstances. Similarly, it is crucial to understand the risk status of the device. By considering these attributes, the device can be successfully assessed through the appropriate regulatory approval pathway.
 https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/640404/MDR_IVDR_guidance_Print_13.pdf https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/946260/IVDD_legislation_guidance_-_PDF.pdf