There are many available substance abuse detection methods on the market, not limited to urine drug testing, saliva drug testing, and hair follicle drug testing. Despite claims made from manufacturers and retailers, it can be difficult to measure the accuracy of individual instant test kits. No drug test is necessarily more accurate than another, but the context of the drug test is important.
How do drug tests work?
Depending on the specimen type, instant drug tests have unique features and are performed in different ways:
- Saliva drug testing: A mouth swab is placed in the donor's mouth for 5-10 minutes, or until enough saliva is collected. Some saliva drug tests include a color indicator to display adequate collection. The swab is then inserted into the kit, where the saliva reacts to built-in test strips.
Mouth Swab Drug Test Accuracy
Saliva drug tests are the most accurate when the goal is to determine recency of drug use. The detection window for saliva drug tests is the shortest of all drug testing methods, which is beneficial if someone is suspected of using drugs onsite.
- Urine drug testing: A test cup or dip card are both applicable for urine testing. A donor must privately collect a specimen using a sterile or integrated cup. Integrated cups with built-in strips will immediately react to the sample. Or, a dip card is inserted into a sterile collection cup to react in the same way.
Urine Drug Test Accuracy
Urine drug tests are used in industries of all types. This traditional method of screening offers a balance of benefits, including an extended detection window and the ability to screen up to 16 different substances.
- Hair drug testing: Once a hair sample is collected close to the donor's scalp, it is sent to a SAMHSA-certified laboratory for analysis. Hair drug testing cannot yield instant results, and interpretation may require a few days.
Drug Test Accuracy Statistics
Most drug tests are 99% accurate in and of themselves; however, the accuracy of results depends on a number of individual factors, including frequency of drug use, cross-reactivity with prescription medicine, length of time between drug use and drug test, and even donor metabolism.
According to WebMD (and accounting for the aforementioned factors), positive results obtained via instant immunoassay are generally 90% true, while negative test results are 85% true. Fortunately, any uncertainty surrounding an instant test result can be qualmed via laboratory confirmation testing.
What is GC/MS Testing?
Gas chromatography-mass spectrometry (GC/MS) testing is applied in certified laboratory settings to confirm initial findings from instant immunoassays. This two-step process involves isolating compounds in a donor's specimen first by size (GC) and then by structure (MS). GC/MS is virtually non-refutable, boasting greater than 99.99% accuracy.
What do they look for in a drug test?
Some devices are able to detect up to 16 different drugs of abuse at once:
- Marijuana (THC)
- Amphetamine (AMP)
- Cocaine (COC)
- Barbiturates (BAR)
- Phencyclidine (PCP)
- Methadone (MTD)
- Oxycodone (OXY)
- Methamphetamine (mAMP)
- Tramadol (TRA)
- Ecstasy (MDMA)
- Opiates (OPI)
- Morphine (MOR)
- Propoxyphene (PPX)
Drug test panels should honor industry organizational guidelines, since it is not necessary to test for more drugs of abuse than necessary, and testing for too few drugs may lead to non-compliance.