The FDA defines a Laboratory Developed Test (LDT) as an in vitro diagnostic test that is manufactured by and used within a single laboratory (i.e. a laboratory with a single CLIA certificate). LDTs are also referred to as in-house developed tests or “home brew” tests.
The Clinical Laboratory Improvement Amendments (CLIA) program regulates laboratories to ensure accurate and reliable test results when laboratories perform testing on patient specimens. The FDA regulates manufacturers and devices under the Federal Food, Drug, and Cosmetic Act (FFDCA) to ensure that devices, including those intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease, are reasonably safe and effective. Similar to other in vitro diagnostic tests, LDTs are considered “devices,” as defined by the FFDCA, and are therefore subject to regulatory oversight by FDA. Although the FFDCA requires manufacturers of all in vitro diagnostic devices (IVDs), including LDTs, to comply with the regulatory requirements governing device safety and effectiveness (such as quality controls for device design and other aspects of device manufacturing, premarket clearance/approval, etc.), the FDA has generally exercised enforcement discretion so that the agency has generally not enforced these requirements for LDTs. LDTs, therefore, generally have not undergone FDA premarket review, which assures both the analytical validity (e.g. analytical specificity and sensitivity, accuracy and precision) and clinical validity of IVDs. Under the CLIA regulations, when a laboratory uses a test system that has not received FDA clearance or approval, such as a LDT, the laboratory may not release any test results prior to establishing certain performance characteristics relating to analytical validity for the use of that test system in the laboratory’s own environment, see 42 CFR 493.1253(b)(2) (establishment of performance specifications).