Medical Device Clinical Trials

Based on the region, there are a variety of classification systems, and definitions and requirements for medical devices also vary.

The US Food and Drug Administration (FDA) is accountable for controlling every step, including clinical trials, to determine if medical devices meet safety and effectiveness standards before they are marketed.

The article below will review the classification of medical devices and discuss which clinical trials need to be conducted and how they are conducted.

The Definition of Medical Device

Medical devices include many products, from simple tiny things like thermometers to complicated enormous MRI machines.

According to the FDA, the medical device is “an instrument, apparatus, contrivance, implant, in vitro reagent or other similar or related article” that is used alone or in combination for one or more following medical purposes:

diagnosis, monitoring, alleviation, treatment or prevention of diseases or injuries
the investigation, modification, replacement or support of the anatomy or physiological processes
control of conception
supporting or sustaining life

Medical devices do not achieve their principal intended purposes by chemical action or by being metabolized.

Classification of Medical Devices and Control Measures

There are more than 1500 different types of devices on the FDA list. Based on the risks of the device use and the level of control necessary to assure safety. All of them fall into one of the 3 categories:

Class I (low risk) – Out of all medical devices, 47% fall into this category and most are subject to general controls, with some exempt from premarket notification requirements. Gauzes, toothbrushes, bandages, and stethoscopes fall into this category.

Class II (moderate risk)—Approximately 43% of medical devices, including suture needles, contact lenses, catheters, and surgical gloves, fall into this category. Pregnancy test kits are also Class II devices but require special controls for approval.

Class III (high risk) – It’s the smallest group, containing devices that support or sustain life, are implanted, or present potential unreasonable risk of illness or injury. This includes pacemakers, heart valves, and implantable defibrillators. HIV test kits are generally Class II devices.

Pacemakers, HIV test kits, ventilators, angioplasty catheters, heart valves, and various other types of implants are in class 3.

As we can see, the risks increase from I to III, and so do the regulatory controls. Class I devices can be subjected to general control only.

Class II devices may require special control for approval, while Class 3, high-risk devices need the latter two plus premarket approval.

You can find more information about these regulatory controls at FDA.gov. To cut a long story short, clinical trials may not be required for some devices. But they are an absolute necessity for all class III and some class II devices.

How are Clinical Trials Initiated?

To conduct a human study in the US, the FDA requires approval of an Investigational Device Exemption (IDE).

Before the FDA gives this approval, multiple factors need to be considered: the background of medical issues, detailed description of the device, previous preclinical and clinical studies, careful risk analysis, patient monitoring and follow-up plan, sample size, and inclusion and exclusion criteria, etc.

After the review, the FDA can decide to approve the trial, disapprove it, or approve it with conditions.

In the latter case, the trial can start if the sponsor agrees to address all conditions listed in the approval letter within 45 days.

The FDA can approve IDE applications for various types of clinical trials, such as Early feasibility studies and pivotal studies. The exact descriptions are below.

Clinical Trials

Early Feasibility Study (EFS) – It may include less than 15 patients. This type of trial is for devices that are in the early stage of development and device design is not final, hence the approval of EFS IDE may be given based on insufficient clinical data.
Feasibility study – A small clinical trial, often including 20 to 100 subjects, designed to provide preliminary data on the device’s safety and efficacy. Instead, it focused mainly on patient safety. Feasibility studies are often required by the FDA to assess the safety and answer basic research questions before they permit conducting the larger pivotal study.
Pivotal study – A larger study that typically follows a successful feasibility study designed to gather sufficient evidence on safety and effectiveness to support a marketing application. Endpoints and sample sizes are statistically driven and provide support for marketing applications. The FDA review here is much more complex than in the case of previous trials.
Post-approval study – even if the FDA approves a medical device, further studies are still necessary to obtain long-term data.

Does Successful Study Imply Device Approval

The short answer is often but not always. Sometimes, alternative clinical or non-clinical data may conflict with study results, or serious safety concerns may be observed in subsequent clinical trials.

This may lead to disapproval or approval with limited indication and the requirement for new, reliable data.

In turn, the study failure does not always lead to premarket approval application disapproval since the FDA claims it is always willing to review all available data to determine whether there is a reasonable assurance that the device is safe and effective

Take-home Points

Not all medical devices require clinical trials to get FDA approval. Companies need to grant IDE approval to conduct clinical trials in the U.S.

There are multiple types of clinical trials, with separate goals, like proving subsequent studies’ safety or demonstrating the device’s effectiveness.

In general, medical device clinical trials include fewer subjects than drug studies.