FDA Issues Guidance on Laboratory Developed Tests (LDT’s)
Laboratory developed test (LDT) is a type of in vitro diagnostic test that is designed, manufactured and used within a single laboratory.
LDTs can be used to measure or detect a wide variety of analytes (substances such as proteins, chemical compounds like glucose or cholesterol, or DNA), in a sample taken from a human body. Some LDTs are relatively simple tests that measure single analytes, such as a test that measures the level of sodium. Other LDTs are complex and measure or detect numerous analytes. For example, DNA variations can be detected from a blood sample, which can be used to help diagnose a genetic disease. Various levels of chemicals can be measured to help diagnose a patient’s state of health, such as levels of cholesterol or sodium.
While the uses of an LDT are often the same as the uses of FDA-cleared or approved in vitro-diagnostic tests, some labs may choose to offer their own test. For example, a hospital lab may run its own vitamin D assay, even though there is an FDA-cleared test for vitamin D currently on the market.
The FDA does not consider diagnostic devices to be LDTs if they are designed or manufactured completely, or partly, outside of the laboratory that offers and uses them.
LDT’s are important to the continued development of personalized medicine, but it is important that in vitro diagnostics are accurate so that patients and health care providers do not seek unnecessary treatments, delay needed treatments, or become exposed to inappropriate therapies.
The FDA has generally not enforced premarket review and other applicable FDA requirements because LDTs were relatively simple lab tests and generally available on a limited basis. But, due to advances in technology and business models, LDTs have evolved and proliferated significantly since the FDA first obtained comprehensive authority to regulate all in vitro diagnostics as devices in 1976. Some LDTs are now more complex, have a nation-wide reach and present higher risks, such as detection of risk for breast cancer and Alzheimer’s disease, which are similar to those of other IVDs that have undergone premarket review.
The FDA has identified problems with several high-risk LDTs including: claims that are not adequately supported with evidence; lack of appropriate controls yielding erroneous results; and falsification of data. The FDA is concerned that people could initiate unnecessary treatment or delay or forego treatment altogether for a health condition, which could result in illness or death. The FDA is aware of faulty LDTs that could have led to: patients being over- or undertreated for heart disease; cancer patients being exposed to inappropriate therapies or not getting effective therapies; incorrect diagnosis of autism; unnecessary antibiotic treatments; and exposure to unnecessary, harmful treatments for certain diseases such as Lyme disease.
To help health care providers and patients better rely on the thousands of laboratory tests that are used every day to diagnose disease or other conditions or guide treatment and to encourage the advance of personalized medicine, on July 31, 2014 the FDA notified Congress of the Agency’s intent to issue a draft oversight framework for LDTs based on risk to patients rather than whether they were made by a conventional manufacturer or a single laboratory. This draft oversight framework includes pre-market review for higher-risk LDTs, like those used to guide treatment decisions, including the many companion diagnostics that have entered the market as LDTs. In addition, under the draft framework, the FDA would continue to exercise enforcement discretion for low-risk LDTs and LDTs for rare diseases, among others. The framework would be phased in over many years.
To read the official guidance, go to http://www.fda.gov/downloads/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm416685.pdf or to http://www.fda.gov/downloads/medicaldevices/deviceregulationandguidance/guidancedocuments/ucm416684.pdf
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