Revised: 10 May 2011

Medical Devices

Risk Classification of Medical Devices

Medical devices are rated by their potential risk from Class I (low) to Active Implantable Medical Device (AIMD, high). The Regulations require a sponsor to determine the correct risk classification of its medical devices. Recent or planned changes to risk classification systems in Europe and Australia mean there are now differences between risk classifications in those regulatory regimes and New Zealand.

Explanation of risk classes

Following the principles of the Global Harmonisation Task Force (GHTF) the New Zealand Regulations have five risk classes and two sub-classes. These classes are based on the potential risk posed by the medical device when used as intended by the manufacturer. The classes are summarised below.

Risk Class	Risk Description	Example
Active Implantable Medical Device (AIMD)	High	Implantable pacemaker
Class III	High	Drug eluting cardiac stents
Class IIb	Medium-High	Ventilators, orthopaedic implants
Class IIa	Medium-Low	Hypodermic needles, suction equipment
Class I sterile	Low	Sterile dressings, non-medicated
Class I measuring	Low	Volumetric urine bag
Class I basic	Low	Reusable surgical instruments

Rules of risk classification

Determining the risk classification is a simple process of working with Schedule 2 of the Medicines (Database of Medical Devices) Regulations 2003 and using a process of elimination to determine the correct classification.

Begin by obtaining a copy of Schedule 2 and read through it. Schedule 2 is available on-line from the Government Legislation Website.

Schedule 2 sets out the 22 rules that are used to determine the risk classification of devices.

• Rule 1 provides the definitions for transient, short term and long term use of a device.
• Rules 2 through 5 relate to non-invasive medical devices.
• Rules 6 through 9 relate to invasive and implantable medical devices.
• Rules 10 through 13 relate to active implantable medical devices.
• Rules 14 through 22 relate to special kinds of medical devices.

How to apply the rules of risk classification

Use a process of elimination to determine the risk classification. Begin the process by working through the 22 rules, commencing at Rule 22 "Medical devices that are mammary implants", and work backwards to Rule 2.

By commencing at Rule 22 and working backwards you will eliminate higher classifications and reach the correct classification easily.

Devices that are not eliminated by any rule are determined to be Class I.

If you are unable to determine the risk classification, refer to the manufacturer of the device. Medsafe is not able to make a determination as to the risk classification of a medical device.

Example:

A cardiac guide catheter used to assist with the delivery of other medical devices to the heart. The catheter is a single use device that is inserted via the femoral artery. The catheter is in place within the patient for approximately 1 hour.

• According to Rule 1 the device is for transient use.
• Rules 22 to 8 do not apply
• Rule 7(1) describes the device
• Rules 6 to 2 do not apply

By the process of elimination the guide catheter has a risk classification of IIa.