FDA Oversight of In Vitro Diagnostic (IVD) Devices Jul 22, 2025

Srilekha Deka, MD, PhD

Script Molecular is a biotech consulting firm in San Francisco, CA.

What is the FDA’s Regulatory Structure?

The U.S. Food and Drug Administration (FDA) regulates medical products used in diagnosis, prevention, and treatment of disease. The agency’s responsibilities are organized by product type into specialized centers:

CDER is the Center for Drug Evaluation and Research
CBER is the Center for Biologics Evaluation and Research
CDRH is the Center for Devices and Radiological Health (including medical devices)

CDRH, through the Division of Microbiology Devices, in the Office of In Vitro Diagnostic Device Evaluation and Safety has regulatory responsibility for in vitro diagnostic devices (IVDs) intended for use in the diagnosis of almost all infectious diseases⁴.

What is an IVD?

Per 21 CFR 809.3, an In Vitro Diagnostic Device (IVD) is defined as⁵:

“In vitro diagnostic products are those reagents, instruments, and systems intended for use in the diagnosis of disease or other conditions, including a determination of the state of health, in order to cure, mitigate, treat, or prevent disease or its sequelae. Such products are intended for use in the collection, preparation, and examination of specimens taken from the human body. These products are devices as defined in section 201(h)(1) of the Federal Food, Drug, and Cosmetic Act (the act) and may also be biological products subject to section 351 of the Public Health Service Act, including when the manufacturer of these products is a laboratory.”

These include molecular diagnostic assays, immunoassays, and point-of-care testing devices.

Determination of Safety & Effectiveness

Prior to marketing a new IVD device in the United States, the FDA requires evidence of reasonable assurance of both safety and effectiveness, supported by valid scientific evidence. In accordance with 21 CFR 860.7(d)(1)³, the determination of a device’s safety and effectiveness for classification purposes considers the following, in addition to other relevant factors:

Intended users: Who is the device meant for?
Intended use conditions: How and under what conditions will it be used?
Benefit-risk analysis: What is the health benefit versus potential harm?
Device reliability: What is the consistency and dependability of device performance?

What is Safety?

A device is considered to have reasonable assurance of safety when valid scientific evidence demonstrates that the probable health benefits outweigh any probable risks. It should be demonstrated that the probable health benefits obtained when the device is used as per the defined intended use, under the specified conditions and with appropriate directions and warnings, outweigh any probable risks. 21 CFR 860.7(d)(1)³ says that such evidence must adequately show that the device does not present an unreasonable risk of illness or injury when used as intended.

What is Effectiveness?

A device is considered to have reasonable assurance of effectiveness when valid scientific evidence demonstrates that it yields clinically meaningful outcomes for a substantial portion of the intended population. Effectiveness is determined when clinically meaningful outcomes are generated when the device is used under the specified conditions and with appropriate instructions and warnings.

Why are they important?

The type of premarket submission, be it a 510(k), De Novo, or PMA, depends on the risk classification and novelty of the device. The FDA classifies medical devices into three regulatory classes, depending on the level of control required to ensure reasonable assurance of safety and effectiveness. This system is based on risk and intended use, as described in 21 CFR Part 860 and reinforced by FDA policy^{1, 2}.

How are devices classified?

The FDA has established classifications for ~1,700 different generic types of devices and grouped them into 16 medical specialties referred to as panels. Each of these devices are assigned a regulatory class (one of three) based on the level of control required for assuring the safety and effectiveness of the device¹.

These three classes are:

Class I General Controls: These are low risk devices where general controls alone are sufficient to ensure safety and effectiveness.
Class II General Controls and Special Controls: These are moderate risk devices that require general controls plus special controls (e.g., performance standards, labelling, post-market surveillance, etc.)
Class III General Controls and Premarket Approval (PMA): These are high risk devices where a PMA is required. Exception to this rule is if the device is a pre-amendments device and a PMA was not called for. A pre-amendment device is a device that was on the market prior to the medical device amendments in 1976 (or substantially equivalent to such a device). In these cases, the route to market will be a 510(k) application¹.

Device classification depends on both the intended use and the indications for use of the device and is also risk based. The risk the device poses to the patient and/or the user is a major factor determining assignment to a class. Devices with the lowest risk are included in Class I and devices with the greatest risk are included in Class III.

Class I, II, and III, are all subject to General Controls. These are the baseline requirements as per the Food, Drug and Cosmetic (FD&C) Act that apply to all medical devices¹.

Practical Application

Manufacturers developing new IVD devices must clearly define the intended use and indications for use for their device. In addition, they need to conduct a thorough assessment of the potential risks and benefits of the device to both patients and users. These steps are critical for determining the appropriate device classification and regulatory pathway, as well as for developing a strategically sound submission strategy.