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Drug abuse screening: get your lab's share of a booming market.

Drug abuse screening: Get your lab's share of a booming market

Drug testing has gained tremendous popularity in the past three years. Although specialty laboratories initially dominated the market, hospital and small reference laboratories have recently begun testing for such abused substances as amphetamines, barbiturates, benzodiazepines, cocaine, methaqualone, opiates, THC, and PCP.

One indication of the market's size: $64 million was spent in the U.S. and $73 million worldwide on various packaged reagent kits in 1985, according to a Boston Biomedical Consultants study.1 These totals, which do not include the thin layer chromatography and confirmation testing market, illustrate the rise of immunological screening systems.

The study also revealed that reference laboratories and the military did the bulk of the U.S. spending on kits, 34 and 31 per cent, respectively, followed by hospitals (19 per cent) and employers performing on-site tests (16 per cent).

Any laboratory that wants to enter or capture a larger share of the market must understand an array of drug abuse testing issues. We will review these issues, starting with the reasons for testing.

Why do employers test? They want to detect drug use in job candidates, in current employees in general, or in employees involved in accidents or other incidents where drugs may have played a part. Each of these reasons for testing has its own requirements and legal implications.

Preemployment testing, generally the last step before hiring, accounts for the vast majority of drug screening programs. Although results usually determine whether someone will land a job, they are often not confirmed. Some companies allow repeat testing at a later date; most do not.

Because it may be considered discriminatory, many states prohibit blanket screening of all job applicants. Even when allowed by law, such programs are quite costly for firms interviewing a large number of candidates.

Some employers collect specimens and perform analyses on-site. A larger number of employers only collect the specimens, often in a nonmedical setting, and send them to a laboratory. This causes logistical problems. Testing laboratories cannot provide routine pickup and transportation of specimens because preemployment testing is commonly cpisodic and infrequent.

Another option is to have third parties handle specimen collection and testing. The collection site may be a physician's office, an emergicenter or other free-standing facility, or a hospital. It isn't always the testing site as well. A hospital that handles other tests for an employer, say as part of a physical examination, would be obliged to collect specimens for drug testing even if the employer wanted them sent to an outside laboratory.

Testing of current employees is usually called random screening. That's likely to mean that scheduling of the tests changes from year to year, not that employees are randomly chosen for scrutiny. It is done without cause--there is no suspicion of drug use. Because of union and employee resistance, few employers conduct this type of screening. Those that do have frequently negotiated the testing with unions.

Random screening commonly involves employees in sensitive positions that affect safety or the integrity of an enterprise. For instance, an individual operating a nuclear reactor might be tested, but members of the bakers' union could successfully argue that the nature of their jobs does not warrant drug screens.

The third type of testing, called incident or for-cause testing, often follows suspected drug- or alcohol-related events. Examples include industrial mishaps, highway or railroad accidents, or unusual behavior on the job. When for-cause testing is necessary, a medical setting is preferred because the person may require immediate medical attention, and blood specimens must be drawn to rule out other medical causes of the accident.

Specimen collection. Urine is preferred over other fluids for several reasons. For one, obtaining the specimen is easy. It does not involve an invasive procedure and can be done in any bathroom.

Drug concentration is usually much higher in urine than in blood. Moreover, many drugs and their metabolites are excreted in urine for a prolonged period after use, so there is a greater chance they will be found days or weeks later. Test procedures are also simpler for urine, which is available in greater quantity than blood.

Incident testing often calls for combined blood and urine tests to determine very recent consumption of drugs. Blood collection, which requires skills found in medical settings, provides hospitals and health care centers with an opportunity for increasing business.

A positive urine test is an excellent indicator of consumption of a drug, but it cannot prove impairment. Nor are blood values absolute proof of impairment for the drugs of abuse that are typically the object of mass screening (except alcohol).

Nevertheless, a positive test is often grounds for dismissal or denial of employment, and a person who has taken drugs may try to conceal usage by tampering with the specimen. The laboratory can take a number of steps to insure test validity.

The most reliable but intrusive method is to have someone witness specimen collection. This involves an obvious violation of personal privacy. Although the method is essentially foolproof, many companies and laboratories prefer other approaches.

One alternative requires an individual to disrobe and change into a hospital-style garment to prevent the substitution of a negative specimen at the collection site. Using a room without any water supply is best but usually not practical. The following precautions can be taken on-site to guard against tampering when a bathroom is used:

Examine the appearance of the urine. Federal guidelines for testing Government employees require the use of bluing agents in toilets to reveal attempts at specimen dilution.

Carry out temperature checks--they are easy and relatively reliable. Thermometers or temperature dots made specifically for urine can reveal specimen temperature at the collection time.

Use dipsticks to determine the specific gravity of the urine. They can indicate if a specimen was diluted or had substances added.

Measure pH with a dipstick to check for the presence of a strong acid or base that might interfere with immunological tests.

Perform simple chemical tests for other commonly added substances.

With any of these steps, maintain the integrity of the specimen by never testing in the original container. Instead, draw off small aliquots for individual tests.

Among testing procedures, immunological methods are most subject to adulteration. Since they do not use extraction techniques to separate certain drugs and they require narrow pH and ionic strength ranges, these tests are easier to interfere with than thin layer chromatography.

The most commonly used adulterant is water, which lowers the concentration of drugs below the detection limit. Other foreign substances that have interfered with drug tests include common table salt and bleach.

On-site testing. Employers can maintain complete control with on-site screening programs. The advantages may include low cost, good turnaround time, and minimized logistical and chain-of-custody problems. But reagent waste, poor utilization of kits, and purchases of ancillary supplies often cancel out any savings.

Prison systems, police agencies, and parole boards form the typical market for this type of testing. Most of these agencies employ Emit because it can be used with many different analyzers, but the U.S. military uses both Emit and Abuscreen.

One drawback of on-site testing is a possible conflict of interest problem, as employers both accuse and judge employees. To avoid legal difficulties with a discharged individual, it is important that skilled personnel perform drug screens, that specimens be properly identified, and that positive results be confirmed.

A different method from the original screen must be used for confirmation testing. The most common are gas chromatography, high performance liquid chromatography, and gas chromatography /mass spectrometry.

Test accuracy. A common question about drug screening is, "How accurate are the tests?' The answer may be expressed as a percentage representing the predictive value of a positive result-- the number of true positives relative to total positives. For example, if the predictive value is 68 per cent, 32 per cent of individuals who test positive will have false positives and could be wrongfully dismissed or denied employment.

The lower the prevalence of true positives in a given population, the lower the predictive value of a positive test. In a population with low prevalence, the predictive value will be poor, no matter how sensitive and specific a test is. The need for confirmatory testing would be particularly acute since most positive results would be false positives.

Role of the laboratory. To deliver the services promised, the laboratory must perform tests in a consistent, reliable manner. This does not mean all tests must be correct, but any error should not be the result of faulty lab procedures. The laboratory should apprise employers of the methods used, their degree of accuracy, and the way results are confirmed. Implied promises of foolproof testing may embroil a lab in legal action if erroneous results lead to the discharge of an employee.

To avoid such difficulties, laboratories should encourage clients to submit blind duplicate specimens, which build credibility and demonstrate that quality control is taken seriously. Laboratory personnel must also understand the methods used, the implications of various medications, and the impact of the results. They cannot merely provide tests without knowing the limitations.

Remember that confidentiality is essential in drug testing. Unless it is carefully guarded, laboratories can be subject to defamation suits. Numeric identification systems and tight security can eliminate the possibility of public disclosure of an individual's results.

Reports should go only to predesignated individuals in companies. The laboratory staff should avoid conversations with unknown parties about test methods and results. Calls from interested but unauthorized parties are far more common than imagined!

Another vital element in drug testing is good record keeping, which laboratories should practice in any event. Since some cases will eventually result in legal action, all requisitions, chain-of-custody forms, worksheets, instrument printouts, and chromatograms should be retained.

Some laboratories sequester paperwork from all positive specimens to insure completeness. Since years may pass before results are requested, identities of lab personnel involved should be indicated by name, not initials.

A good chain of custody is necessary for identifying a specimen in a medicolegal setting. This audit trail documents the passage of a specimen from party to party and whether it has been opened. Any specimens not under direct surveillance should be placed in a locked refrigerator or freezer.

Proper specimen identification is a popular issue with defense attorneys, especially when confirmatory gas chromatography/mass spectrometry has been performed and there is little chance to contest the scientific validity of a result. It is important to note that if collection and transportation are not under its control, the laboratory can only attest to the integrity of the specimen on its premises.

Selecting a method. The most frequently used screening methods are chromatographic or immunological. Chromatographic procedures include thin layer chromatography (TLC) and the prepackaged Toxi-Lab system. Immunological systems include Emit, Abuscreen, and TDx.

TLC can detect between 40 and 50 drugs. Although it needs little equipment and is relatively inexpensive, it has a number of disadvantages: It is labor-intensive, requires a high skill level to interpret plates, and involves a specimen extraction step. The procedure is excellent for detecting drug overdoses, but it is less than ideal for screening healthy individuals.

Immunological methods such as radioimmunoassay, enzyme immunoassay, and fluorescence polarization immunoassay are most commonly used by hospital and reference laboratories. They are easily automated, have no extraction steps, require minimal labor, produce an objective result, and detect drugs at lower levels than TLC. The drawbacks are that fewer drugs can be detected, the cost per test is high, and an expensive analyzer is required.

In summary, industrial drug testing is a market that can enable hospitals to increase their laboratory revenue. However, it requires knowledge and skills not routinely available in the typical clinical laboratory. Any lab seeking a share of the market must weigh its resources and ability to adapt against the demands posed by this burgeoning specialty.

1. "U.S. Market Estimate of Manufacturer Sales.' Waltham, Mass., Boston Biomedical Consultants, 1986.
COPYRIGHT 1987 Nelson Publishing
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 1987 Gale, Cengage Learning. All rights reserved.

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Author:De Cresce, Robert P.; Lifshitz, Mark S.
Publication:Medical Laboratory Observer
Date:Oct 1, 1987
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