TGA Guidance on Clinical Evidence: Comparable Devices in Detail

Table of Contents

The Therapeutic Goods Authority (TGA), an Australian regulatory agency in the sphere of healthcare products, has published a guidance document dedicated to clinical evidence for medical devices. The document provides an overview of the applicable regulatory requirements, as well as recommendations to be taken into consideration by medical device manufacturers and other parties involved to ensure compliance thereto. The scope of the guidance covers, inter alia, the aspects related to comparable devices. 

It is important to mention that provisions of the present guidance are non-binding, nor are intended to introduce new rules or impose new obligations. The authority also reserves the right to make changes to recommendations provided therein, should it be reasonably necessary to reflect corresponding changes to the underlying regulations. 

Predicates 

According to the guidance, the term “predicate” applies to a similar medical device already placed on the market and used as a reference for a new application by demonstrating substantial equivalence. As further explained by the TGA, a predicate:

• Is a previous iteration of the subject device;
• Has the same intended purpose as the subject device;
• Is within the same lineage of devices as the subject device;
• Is from the same manufacturer as the subject device.

Based on the above, it could be stated that the way TGA interprets the term “predicate device” is slightly different from the way the same term is interpreted by other regulating authorities, for example – by the US Food and Drug Administration (FDA). 

According to the document, substantial equivalence should be demonstrated for the clinical data related to a predicate device to be used to substantiate the marketing application for a new device subject to review. The authority additionally emphasizes the importance of taking into consideration the aspects related to safety and effectiveness, and the way they are affected by differences existing between the two devices. 

Comparing Device Characteristics 

The authority further describes the approach to be applied when comparing characteristics of medical devices, including the clinical, technical, and biological ones. In this respect, the TGA additionally emphasizes that the medical devices with a high risk associated thereto should be subject to a more rigorous assessment. Comparison of characteristics allows us to determine the degree of similarity. It is also explicitly stated that to demonstrate substantial equivalence, the devices must be similar to such an extent that there would be no clinically significant difference in clinical safety and performance. 

Under the general rule, only one existing device should be used in the comparison, except the cases when all the products are from the same lineage. However, the authority mentions that in certain cases a comparison involving multiple devices could be appropriate – for example, in the following situations:

• Where a subject device is part of a system of devices (in this instance, comparisons may address the multiple devices within the system, including how the individual components of the system interact and the safety and performance of the system as a whole);
• Where technical differences between devices are present (discussion of the impact of the technical difference may be supported by a relevant example from a third device). 

In the situations described herein above, the clinical evidence related to the devices should be sufficient to assess the matters related to the safety and effectiveness of a medical device in question. 

The authority also mentions that the party responsible for a medical device should duly identify any concerns related to the safety or effectiveness, especially the ones that triggered regulatory actions in any jurisdiction the device is available. 

Clinical Characteristics and Intended Purpose 

First of all, the scope of assessment should cover the aspects related to the clinical characteristics associated with the intended purposes of the device. For the guidance, the intended purpose refers to the clinical condition being treated, the severity and stage of disease, the site of application to/in the body, and the patient population. The said information should be indicated in the application. It is further stated that when assessing the device, the authority will also pay attention to consistency within the information provided in all the documentation accompanying the device as provided by its manufacturer. According to the guidance, attention will be paid to the matters related to the comparability of the subject device and comparable device concerning:

• Indications for use, including the disease or condition the medical device will diagnose, treat, prevent, cure or mitigate;
• Patient population (for example, age, gender, anatomy, physiology);
• The site of application to/in the body (organs, part of the body, tissues, or body fluids contacted by the medical device);
• Type of contact (for example, contact with mucosal membranes, invasiveness, implantation);
• Duration of use or contact with the body;
• The environment of use (for example, healthcare facility, home);
• Intended user (for example, use by health care professional, lay person);
• Repeat applications, including any restrictions as to the number or duration of applications. 

The authority mentions that the intended purpose should be the same for both products for substantial equivalence to be established. At the same time, in case the intended purpose is slightly different, but still covered by the scope of the intended purpose of the comparable device, clinical evidence related to such device could still be used. 

In summary, the present TGA guidance describes the concept of predicate devices and explains the way they should be used. The document also highlights the key points to be taken into consideration when assessing the characteristics of medical devices in the course of comparison. 

Sources:

https://www.tga.gov.au/sites/default/files/clinical-evidence-guidelines-medical-devices.pdf

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