How do labs implement molecular tests to meet complex clinical needs?
Laboratory developed tests (LDTs) and In Vitro Diagnostics (IVDs) are both in vitro diagnostic tests using body fluids (such as blood or urine) or cells/tissues (e.g., pap smear, biopsy) to detect or quantify levels of a desired biomarker. As LDTs and IVDs are both used to diagnose health conditions, it is crucial to understand the differences and advantages.
Differences between IVD tests and LDTs
In vitro diagnostic test
Laboratory developed test
Developed for sale to diagnostic laboratories, health clinics, or consumers
Standardized instrument qualification procedures and training required
Must be pre-validated with a data analysis and bioinformatics report
Must be clinically validated
Developed by individual laboratories; not transferred, licensed, or sold
Instrument qualification and training requirements established by individual laboratories
Often developed in-house by necessity—no standard assay available
Must be clinically verified and can be implemented quickly for emergency use*
*Must comply with the Clinical Laboratory Improvement Amendments (CLIA) of the U.S. Centers for Medicare and Medicaid Services.
Advantages of IVD and laboratory-developed testing in the lab
Quality system—Tests subject to number of requirements (design controls, manufacturing controls, and handling complaints)
Clinical validity—Helps ensure test detects or measures specified target analyte, or that it is useful for determining presence/absence of clinical condition or predisposition, prior to marketing
Technical support from supplier—To troubleshoot and replace faulty products
Broad distribution—Many laboratories utilizing the test provide data that can increase (or possibly decrease) confidence in the test. Laboratories performing the same IVD test can report proficiency results to confirm the accuracy of the test.
Simplified inventory control—Only order manufactured tests for anticipated use, which reduces the amount of documentation required. Requires less time and effort to maintain in-house IVD inventories.
Rapid adaptation—LDTs can be developed and modified relatively quickly to respond to market needs
Control over content—Laboratories can select specific and relevant targets
Lower cost per test—Technological advances and the availability of off-the-shelf bulk reagents have made complex analyses faster and more affordable
Laboratory qualification—The laboratory quality management system (QMS) covers all tests, including LDTs, which is not the case for IVD kit production
Consolidation into a single test—Testing for multiple analytes provides more data per sample and may enable faster diagnosis
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