Choosing a Drug Test Panel: Concepts and Considerations

All of the drugs employers can test for, except phencyclidine, methaqualone, Ecstasy, and LSD, have some legitimate medical uses.

For employers, deciding to implement a drug abuse testing program is only the first step in a process that requires planning and forethought. To be successful, many decisions must be made to ensure the program truly meets your goals--beginning with determining which drugs to test for. To make this determination and other related decisions, it's key to first understand what drug abuse testing can and cannot tell you and how the urine testing process works.

Drug Abuse vs. Drug Use
First off, you'll note the process is called "drug abuse testing," not "drug testing." This is an important distinction. What you are looking for is drug abuse, not legitimate drug use. You don't want to know whether an employee is taking an amphetamine for attention deficit hyperactivity disorder as prescribed by his doctor, which is an example of legitimate drug use. What you do want to know is whether that person is taking "speed" for its rush or to combat the fatigue of working two jobs, which is an example of drug abuse. If a negative employment decision is made based on an applicant's legitimate drug use, the decision could be found to be discriminatory under ADA or other employee protection laws.

Use vs. Impairment
Drug abuse testing tells you nothing about how impaired the donor is. All it tells you is the level of drug in the donor's urine. Impairment is really a medical decision that is best made by a health care provider through a physical and mental status exam.

A high level of a drug in the urine doesn't mean the donor is impaired, just as a low level doesn't mean the donor is not impaired. The exception to this is alcohol. Breath alcohol levels correspond to blood alcohol levels that, in turn, correspond to impairment.

The Testing Process
Labs that run drug abuse testing conduct two different types of tests on urine specimens. The first is a screening test using a process called immunoassay testing. Immunoassay tests use antibodies to detect the presence of a drug or metabolite in urine. This type of test is not very specific for the drug being tested for, but it doesn't have many false negatives. In other words, some of the tests this method calls positive may not really be positive, but all of the tests it calls negative are really negative.

If the screening test is positive, then the lab runs the urine through a second, more specific testing process called gas chromatography/mass spectrophotometry (GC/MS). During the GC/MS test, drugs or drug metabolites are extracted from the specimen, physically separated, and identified. This test is like fingerprinting--if it comes back positive, then the drug is present.

There are a number of reasons why GC/MS isn?t used on every specimen. It's much more expensive than immunoassay testing and can take days to get results. It's technically a more difficult testing process and takes special training and skills to run.

What is Really Tested For
When discussing drug abuse testing results, it's common to say positive for marijuana or cocaine. Technically, however, that is inaccurate. The lab does test directly for certain drugs, but for marijuana, the test is really for THC (tetrahydrocannabinol), the active substance found in marijuana. For cocaine, the test is for benzoylecgonine (a metabolite of cocaine).

Cut-Off Levels
When the lab calls a drug test a negative, it doesn't mean that no drug was found in the urine. It means the amount of drug found in the urine didn't exceed the established cut-off levels. Cut-off levels are not zero in order to account for possible passive inhalation. For example, a person in a room with marijuana smokers will inhale some smoke. The drug is excreted in the urine and may come up at a very low level when the person is tested.

The Role of the MRO
In the drug abuse testing process, MROs (physicians with special training in all aspects of drug testing and drug abuse) are responsible for determining whether a confirmed positive result indicates legitimate drug use or drug abuse. A confirmed positive result means the lab has checked the specimen twice, using two different methods, and is sure the drug is present in the urine at or above the accepted cut-off level. Legitimate drug use or drug abuse, however, must still be determined. All of the drugs employers can test for, except phencyclidine, methaqualone, Ecstasy, and LSD, have some legitimate medical uses. For example, THC (tetrahydrocannabinol), the active ingredient in marijuana, is found in the drug Marinol, which is used by some cancer patients undergoing chemotherapy and by certain patients who are HIV positive.

The Medical Review Officer (MRO) investigates confirmed positives by reviewing the results and talking to the donor.
The Medical Review Officer (MRO) investigates confirmed positives by reviewing the results and talking to the donor. If the MRO determines the presence of the drug in the urine is the result of drug abuse, the result will be a verified positive. If the MRO determines the presence of the drug in the urine is the result of legitimate drug use, the result will be a verified negative.

What Drugs Should You Test For?
Of the thousands of legal and illegal drugs available, how do you decide which ones to test for? Here are some considerations to help you arrive at the appropriate number for your organization:

  • Test for drugs that are commonly abused.
  • There's no reason to test for drugs that have no abuse potential, such as medications taken for heart disease, diabetes, arthritis, etc.
  • Consider federal government guidelines for testing.
  • The federal Department of Transportation long ago established the five drugs it believes are the most commonly abused. Called the "DOT 5," they are: marijuana; cocaine; amphetamines/methamphetamine; opiates (codeine, morphine, and heroin); and phencyclidine (PCP). There are many other drugs of abuse that could have been added to DOT's list (such as opioids, propoxyphene, methadone, benzodiazepines, barbiturates, LSD, Ecstasy, methaqualone, etc.), but DOT decided these five drugs would become its standard.
  • Consider costs for additions to the standard 5-panel.
  • The more drugs you test for, the more it will cost you. The lab costs will be greater because there are more tests that need to be run. You may be charged more for your MRO services because there will be more positives resulting in more work for the MRO.
  • Consider how testing for additional drugs will affect turnaround time.
  • Most of your negative drug abuse testing results are reported back within 24-48 hours because the MRO doesn't have to contact the donor. In the event of a confirmed positive, under DOT guidelines, the MRO must try for 10 days to contact the donor. If the donor provides a legitimate explanation for the drug use, the donor has five additional business days to obtain documentation supporting the legitimate use of the drug. The MRO must then verify the information provided by the donor.
  • Consider potential exposure to drugs in your industry.
  • Certain industries, such as health care, have a higher incidence of employees abusing certain types of drugs, because there is increased availability of the drugs. If your employees have access to many drugs, it may be reasonable to add these drugs to your panel.
  • Consider the odds of additional verified positives.
  • The odds are slim that certain drugs, such as barbiturates and methadone, will test positive, so it may not make sense to test for them. By contrast, the odds are much higher that are other drugs, such as benzodiazepines, will test positive.

Data for Designing Your Panel
As an MRO, over the past two and half years I have been collecting data for a study on my verified positive cases. The study contains information on 2,178 positive donors with 2,293 positives. (One hundred and nine donors were positive for two drugs, and six were positive for three drugs.) It sheds some interesting light on which drugs most often come up as verified positives, which could factor into their applicability for an employer's test panel.

Data from the study strongly suggests that, at a minimum, employers should opt for a DOT-5, or 5-panel test. It shows that 82.7 percent of verified positives were for one or more of these five drugs. The 5-panel test will catch the vast majority of drug abusers.

Many of the drugs included in expanded drug abuse testing panels are commonly prescribed by physicians for pain control, treatment of anxiety or insomnia, or for controlling seizures--which would result in a confirmed positive test result but not a verified positive test result. Thus, an employer who opts to test for these drugs may see many positive results reported by the lab that can be legitimately explained by the donor. For these drugs, the number of verified positives found in the study is as follows:

  • Propoxyphene
  • (the active ingredient in Darvocet, Darvon, Propoxy, and others) is a commonly abused pain killer. In my data, 84 of the confirmed positives were for propoxyphene, but only 21 (25 percent) of these cases turned out to be verified positives, indicating drug abuse.
  • Benzodiazepines
  • (Valium, Xanax, Ativan, Halcion, and many more) are used to treat anxiety, sleeping problems, and depression. People who overuse these drugs can become addicted. In my data there were 78 confirmed positives, but only 24 (31 percent) verified positives.
  • Barbiturates
  • (phenobarbital) are used primarily to treat seizures. They also are found in certain pain pills that are used primarily by migraine headache sufferers and in a few medications used to treat stomach problems. In the past, before benzodiazepines, they were the primary drug for treating insomnia. Barbiturates have low abuse potential. I found 65 confirmed positives but only 6 (9 percent) verified positives.
  • Methadone
  • is a drug used to treat heroin addiction and for pain control. It's against DOT regulations to operate a motor vehicle that falls under the DOT's control when taking this drug. However, it's not included in the DOT 5-panel. I found only 17 confirmed positives for methadone, with 3 (18 percent) reported as a verified positive.
  • Ecstasy
  • (methylenedioxymethamphetamine) is in the amphetamine family and is a popular street drug. It has no legitimate medical uses. There have been proposals made to the DOT to add it to the standard 5-panel test, but so far this hasn't happened. In my data, there were only three verified positives for Ecstasy.
  • Opioids
  • (oxycodone, hydrocondone, Oxycontin, Tylox, Percocet, Vicodin, and many more) is a class of drugs that are semi-synthetic or synthetic pain relievers and as strong as opiate drugs. They have the same side effects and potential for abuse. It's a common misconception that drugs such as oxycodone and Oxycontin will show up in a test for opiates; they will not. In my data, there were two cases of confirmed positives for opioids. Of these, both were verified positive.
  • Methaqualone
  • (Quaaludes) is a "downer," depressing the nervous system. This drug is no longer manufactured, and few companies test for it. In my cases, there has not been a positive for this drug.

The number of drugs you can add to your testing panel is large, and employers should consider their return on the extra cost and potential delay in receiving drug test reports. There is no one right answer; each employer has to decide what's important to it.

The first step in establishing a drug abuse testing program is understanding the urine-based testing process and what it can tell you. With this understanding, you can make a reasonable decision on which drugs you want to include in your panel--based upon how much you want to spend, your time frame for getting your results, and the risks specifically related to your workplace. If you opt to test for more drugs, you will need to consider the expense, the increased chance of having verified positives for drugs that are rarely abused, and potentially longer turnaround time for receiving confirmed positive, verified negative results.

Establishing a preplacement drug abuse testing program is only one step in implementing a drug-free workplace program. The other components--education, testing at other times, and an employee assistance program--also are essential for the success of your program.

This article appeared in the April 2005 issue of Occupational Health & Safety.

This article originally appeared in the April 2005 issue of Occupational Health & Safety.

Download Center

Featured Whitepapers

OH&S Digital Edition

  • OHS Magazine Digital Edition - June 2021

    June 2021


      High-Visibility 101: Everything You Need to Know
      Seven Tips for How to Choose and Use SRLs
      How to Keep Employees Safe in 2021
      The Heat is Coming - Keep Your Cool Indoors and Out
    View This Issue