Diagnostic Kits/Glossary
Abbreviations
The table below is a list of commonly used abbreviations throughout this wiki.
| Abbreviation | Definition |
|---|---|
| 510(k)/PMA | Pre-Market Notification |
| ASR | Analyte Specific Reagent |
| CLIA | Clinical Laboratory Improvement Amendments Act |
| CMS | Centers for Medicaid and Medicare Services |
| FDA | Food and Drug Administration |
| IVDs | ''In Vitro'' Diagnostics |
| IVDMIAs | ''In Vitro'' Diagnostic Multi-Variate Assays |
| LDTs | Laboratory Developed Tests |
Analyte Specific Reagent (ASR)
Generally, the term “analyte specific reagent” or “ASR” is used to describe a component of a genetic test that is commonly sold or used with a “testing kit.” Scientists use the term to describe certain types of biochemical, chemical, or other substances, and occasionally devices, that are used to conduct a test at a laboratory. However, because the FDA regulates the use and sale of ASRs to some extent, the definition used within the FDA regulations is also commonly used in practice.
Although ASRs are often defined in layman’s terms as the “building blocks” or “active ingredients” of a test, it's helpful to understand how genetic tests are brought to market. Genetic tests tend to be developed either as a "Testing Kit" which is commercially sold to laboratories who conduct the tests, or as a "Laboratory Developed Test" (or LDT), which is developed by a laboratory solely for "in-house use," and is not commercially sold to other entities.
- Testing Kits: When a device manufacturer develops a genetic test and sells it to a laboratory who will collect the specimen and actually conduct the test, they sell the test as a "kit" that includes all the necessary ASRs, as well as instructions on how to conduct the test.
- LDTs: when a testing laboratory develops its own genetic test, including the ASRs, and uses the test (also called a in-house, home brew, or LDT) only at their testing laboratory and does not commercially sell the test to anyone else.
The differences of how the test is developed and sold is important for regulatory reasons. Different federal regulations apply to the sale and use of ASRs. This depends on whether the ASR is being used soley for in-house use at a laboratory (i.e., LDTs), or if it is being sold commercially by testing manufacturers as part of a kit.
For regulatory purposes, the FDA defines ASRs as:
- “antibodies, both polyclonal and monoclonal, specific receptor proteins, ligands, nucleic acid sequences, and similar reagents which, through specific binding or chemical reaction with substances in a specimen, are intended for use in a diagnostic application for identification and quantification of an individual chemical substance or ligand in biological specimens.”[1]
For more information on the regulatory distinctions of ASRs see our wiki page on U.S. Regulation.
See Also:
- FDA Regulations on ASRs
- Wikipedia Definition
- Medical Device Industry.com
- How Lab Tests Get to Market
- AACC.org Resources
Clinical Laboratory Improvement Amendments (CLIA)
See CMS Regulations
Analytical & Clinical Validity & Utility
One problem that is repeatedly encountered in literature is how to quantify the proficiency and usefulness of a particular genetic test. At present, there are no universally established standards for genetic tests to determine proficiency and usefulness by a regulatory body. However, Professional Associations, Laboratory Accreditation Organizations, Policy Groups and Patient Advocacy Organizations all seem to agree that the follow criteria are important when addressing these questions.
- Analytical Validity: refers to the level of accuracy and consistency with which a particular genetic characteristic, such as a DNA sequence variant, chromosomal deletion or biochemical indicator, can be identified in a given laboratory test.
- Clinical Utility: defines the risks and benefits associated with the introduction of a test into practice, including the impact of positive and negative test results on health outcomes, cost-effectiveness, and ethical, legal and social issues associated with test use.
- Clinical Validity: refers to the accuracy of a test when used to identify the presence of disease or predict a patient's clinical status.
See Also:
Genetics vs Genomics
Genetics
Genetics is a term that refers to the study of genes and their role in inheritance - the way certain traits or conditions are passed down from one generation to another. Genetics involves scientific studies of single genes and their effects. Genes (units of heredity) carry the instructions for making proteins, which direct the activities of cells and functions of the body. Genes influence traits such as hair and eye color as well as health and disease development. Genetics determines much (but not all) of a person's appearance and health status, but environmental differences also play a part. Examples of single gene disorders that would be considered as "genetics" include cystic fibrosis and PKU (phenylketonuria).
See Also:
Genomics
Genomics is a relatively new term that describes the study of all of a person's genes including interactions of those genes with each other and the person's environment. Genomics involves the scientific study of complex diseases such as heart disease, asthma, diabetes and cancer because they are caused more by a combination of genetic and environmental factors. Genomics is offering new possibilities for therapies and treatment of some diseases, as well as new diagnostic methods. The major tools and methods related to genomics studies are bioinformatics, genetic analysis, measurement of gene expression, and determination of gene function.
See Also:
Typology of Genetic Tests
See Regulatory Classifications of Genetic Tests
In-Vitro Diagnostic Multivariate Index Assay (IVDMIAs)
See Regulatory Classifications of Genetic Tests
Direct Access Testing (DAT)
"As with home testing, direct access testing (DAT) has been growing in popularity over the past few years. Currently, 34 states permit consumers to order their own lab tests - without a medical order from their health care provider. Also known as patient authorized testing, DAT is a reflection of Americans' focus on health and preventive medicine, offering the opportunity for patients to take a more active role in their own health care.
In some respects, direct access testing has been around for some time. Over-the-counter home tests are a type of DAT since they do not require a prescription and can be bought and used at the consumer’s discretion. Now, the trend has expanded to include laboratories offering clinical tests at the patient’s request. In retail centers in Colorado, Montana, Missouri, Kansas, and Utah, patients can walk into a lab and request certain tests; wellness centers offer health screens and other lab tests; and free-standing and mobile testing facilities offer screening tests to the public, such as in grocery stores and pharmacies.
Most DAT labs limit the availability of tests to simple, general health tests such as complete blood counts (CBC), cholesterol levels, throat and urine cultures, diabetes screening (blood glucose tests), chemistry panels, PSA for prostate cancer, thyroid tests, HIV antibody tests, blood typing, pregnancy tests, and urine drug screens.
Direct access testing may reduce costs for the patient by eliminating the expense of doctor’s office visits, providing vital information to patients who are concerned with a particular health problem or who may otherwise avoid testing due to inconvenience or concerns over anonymity. However, most insurance companies do not cover tests that are not ordered by a physician; therefore, you should expect to pay out-of-pocket for these services. In addition, labs providing DAT services must provide consumers with reference ranges and some assistance in interpreting the results. However, you are not operating under the guidance of your physician, who may be better able to determine what tests you really need but also what the results of those tests mean in light of your specific clinical signs, symptoms, and medical history." [1]
Direct to Consumer (DTC)
IVDs sold directly to consumers who operate the tests themselves. Also known as Over the counter (OTC) or home-based kits. Some DTC products may also be considered DAT products. In these cases, the consumer collects the sample themselves with a sampling kit and mails it away for analysis in a commercial lab (DNAdirect's products work this way). In most DTC IVDs, such as home pregnancy tests or blood glucose tests, the sample collection and analysis happens together in the home.
"While the majority of diagnostic tests are conducted by clinicians and laboratory personnel, individual consumers also purchase diagnostics for private use in their homes. The market for home testing devices expanded from $1.19 billion in 1994 to $4.8 billion in 2002. Among home testing devices approved by the FDA are those that measure cholesterol levels, glucose levels, vaginal pH levels, blood clotting time (for patients on blood thinning drugs such as warfarin) and the presence of fecal occult blood (for detecting colon cancer). The FDA also has approved home testing devices that test for hepatitis C virus (HCV) and HIV, as well as for detecting menopause, pregnancy and drug abuse. The most frequently used home testing devices include blood glucose monitors for diabetics, pregnancy tests and cholesterol tests." [1]
- [1]Goodman et al. The Value of Diagnostics: Innovation, Adoption and Diffusion Into Health Care. (2005) pp. 58-59
Reference Lab
"When diagnostic capabilities are needed beyond those provided in hospitals and physician practices, analysis is conducted in reference labs. While reference labs comprise only 2.8% of all clinical labs within the US, these facilities are responsible for 32% of the diagnostic industry’s revenue, due to their focus on processing large volumes of diagnostic tests for a broad client base. Reference labs generally perform both routine testing and esoteric testing. The largest reference labs may conduct more than 4,400 different types of tests, ranging from high-throughput routine tests (e.g., routine culture, cholesterol tests, Pap smears) to complex or specialized diagnostic tests for Lyme’s disease, cancer, cardiovascular disease and HIV." [1]
"Reference labs are usually private, commercial facilities that do high volume routine and specialty testing. Most of the tests performed are referred from physician’s offices, hospitals and other health care facilities (e.g., nursing homes and other facilities). While most hospitals try to do as many tests as possible in-house, reference labs are used for specialized tests that are ordered only occasionally or that require specialized equipment." [2]
"The major national reference labs including Quest, LabCorp, Specialty/Ameripath, Mayo and others account for at least 60% of the market for esoteric test services. The remaining 40% is shared by a group of some 3000 small, local market laboratories. The major reference labs have built a comprehensive menu of specialized test services and continue to expand their offerings via collaborations with leading medical research centers. They offer a huge presence in the market and manage distribution networks that touch just about every medical specialty. Thus many CLIA-registered company sponsored test services avail themselves of the marketing resources offered by the national reference labs." [3]
- [1] Goodman et al. The Value of Diagnostics: Innovation, Adoption and Diffusion Into Health Care. (2005) pp. 28
- [2] http://www.labtestsonline.org/lab/labtypes-3.html
- [3] Rosen. Diagnostic Test Service Commercialization: A Roadmap to Diagnostics in the 21st Century. (2008) pg. 22
Pharmacogenetics & Pharmacogenomics (PGx)
Pharmacogenetics and/or pharmacogenomics (PGx) is the study of differential drug response due to genetic variation. The two terms tend to be used interchangeably, although the -genetics suffix suggests studies and assertions involving tens of genes while -genomics suggests hundreds or thousands. Many clinical applications to date have focused on drug-metabolizing enzymes such as CYP450s. Other tests examine tens of genes to predict the most efficacious anti-cancer drug. In general, PGx studies attempt to rationally optimize drug choice and dosage while minimizing side-effects.
Drug developers are increasingly including PGx studies in clinical trials and subsequently marketing both PGx diagnostics and the drug or drugs indicated by the test. Note that the included diagnostic does not necessarily help diagnose the condition, but instead determine the appropriate therapeutic response.
See the recent paper by Flockhart et al for a review of 11 pharmacogenomic diagnostics currently on the market.
Pre-market Approval (PMA)
510(k) Pre-Market Notifications
See FDA 510(k) Pre-Market Notifications
Back to Diagnostic Kits
- ↑ FDA Regs., Definition of Analyte-Specific Reagents, 21 C.F.R. § 864.4020.