How to judge the equivalence of medical devices

The equivalence demonstration is a process to judge whether the declared product is equivalent to the selected comparison medical device. If the comparison product can prove that it is basically equivalent to the declared product through demonstration, the comparison product can be regarded as the equivalent product of the declared product, and clinical evaluation of the same variety can be conducted.

The equivalence evaluation mainly includes three aspects, including the application scope, technical characteristics and biological characteristics. See the appendix for the specific equivalence determination process.

1、 Equality determination process

1. Application scope equivalence determination

The products for equivalence demonstration should first have the same scope of application. Based on the same scope of application, further compare the technical characteristics and biological characteristics to prove that they are basically equivalent. Therefore, it is necessary to compare the scope of application of the product first. The scope of application here is not only limited to the intended use specified in the registration certificate, but also takes into account information such as adaptation to the population. The comparison items in the scope of application include the following 11 aspects (except those that are not applicable):

(1) Indications: including diseases or symptoms prevented, diagnosed, relieved, treated or monitored by the device;

(2) Applicable population: such as age, gender, weight and other restrictions on the applicable population;

(3) Applicable parts: such as specific human body parts, organs, tissues, body fluids, etc. for clinical application;

(4) Contact mode and time with human body: such as implantation or body surface contact, contact time, contact times, etc;

(5) Severity and stage of the disease: such as the name, classification, stage and severity of the disease;

(6) Use conditions: such as use environment (household, hospital, specific department, operating room, ambulance, etc.), equipment or drugs used together, user requirements, etc;

(7) Reuse: such as whether it can be reused, the number and time of reuse;

(8) Method of use;

(9) Contraindications;

(10) Warnings and precautions;

(11) Others.

By comparing the application scope and clinical use related information of the declared product and the comparison device, identify, elaborate and evaluate the differences between them to determine whether the application scope is the same. When the difference in the scope of application leads to a significant difference in the risks between the two, the clinical safety and effectiveness are significantly different, and it is considered that the scope of application of the comparison device and the declared product is different. It should be noted that differences in the scope of application do not necessarily lead to differences in the scope of application. For example, if the application product and the comparison device have different indications but belong to the same nature of use, they can be considered to have the same scope of application. The enterprise shall provide sufficient homogeneity explanation for the difference of indications does not lead to the difference of intended use.

2. Comparison of technical characteristics and biological characteristics

After confirming that the declared product has the same scope of application as the comparative medical device, the registration applicant shall provide sufficient information on the technical characteristics and biological characteristics and compare them item by item.

(1) Technical features include:

① Design information:

-Working principle and action mechanism;

-Device design characteristics and basis: such as composition, materials, product structure characterization (applicable methods can be selected according to product characteristics, including structural drawings, three views, exploded drawings, local detail enlarged drawings, engineering drawings, etc.), dimensions and tolerances, software, etc;

-Declare the major characteristics of the device and specify its use in the overall design and scope of application; If there is no clear purpose, the specific design or component shall focus on how to promote the overall use and function of the declared device.

② Material:

-Due to direct contact with human tissues, some products, especially implantable medical devices, need to indicate the detailed and complete chemical composition of the constituent materials, and identify additives, such as colorants, coatings or other surface modifiers;

-The material processing method (such as forging or casting) and its state (such as amorphous or crystalline) of some products may affect the safety and effectiveness of the products, which shall be listed when applicable;

-In addition to the common components of medical devices, some products may involve biological agents, drugs, coatings, additives, etc.

③ Energy: such as energy transmission to devices (such as the use of batteries), energy transmission (such as X-ray, laser, radio frequency, ultrasound) that is a part of device functions and has an impact on patients and/or medical personnel using products.

④ Product performance, function and other key technical features:

-From the perspective of testing methods, such as laboratory testing, computer simulation, animal testing, other non clinical studies simulating clinical use, etc.

-From the perspective of technical characteristics, such as fatigue, wear, tensile strength, compression, flow, burst pressure, software/hardware characteristics, software core algorithm, density, porosity, in vitro degradation characteristics, principles of test methods, etc.

Biological characteristics mainly include: degradation performance, biological response (such as immune response, tissue integration, etc.), etc.

When demonstrating equivalence or analyzing differences, the registrant shall provide corresponding supporting materials as effective scientific evidence of safety and effectiveness equivalence, such as technical requirements, instructions, literature research, etc., and general descriptions are usually insufficient as supporting evidence. The supporting data shall generally include accurate, reliable, complete and traceable data, including the data generation process when necessary. It is recommended that the test/experiment data should come from the laboratory with good quality control.

The comparison products that pass the equivalence demonstration are generally in the following two situations:

The declared product has the same scope of application, technical characteristics and biological characteristics as the reference device;

The declared product has the same scope of application, similar technical characteristics and biological characteristics as the comparison device; There is sufficient scientific evidence to prove that the declared product has the same safety and effectiveness as the reference device.

2、 Problems in Equality Determination

1. During the equivalence demonstration, due to different product functions and designs, there is a need to conduct clinical evaluation with multiple products. For example, the functional model of the product covers the functions of multiple products. At this time, it can be compared with different comparative products according to the functional modules or models; However, the products as similar as possible to the declared products shall be selected as the comparison devices.

2. When there are differences in technical characteristics between the comparison product and the declared product, whether the differences in one aspect cause different safety and effectiveness problems will vary depending on the specific product and different situations. The product is inferior to the selected comparison product in some technical characteristics, but other products (with the same scope of application) that have been marketed have the same technical characteristics as the declared product. At this time, the registrant can demonstrate that the difference does not affect the safety and effectiveness through relevant supporting materials, and demonstrate whether it is fully affected by the difference size and supporting materials.