Interference by nonsteroidal anti-inflammatory drugs in EMIT and TDx assays for drugs of abuse

Rational Urine Drug Monitoring in Patients Receiving Opioids for Chronic Pain: Consensus Recommendations

Objective

To develop consensus recommendations on urine drug monitoring (UDM) in patients with chronic pain who are prescribed opioids.

Methods

An interdisciplinary group of clinicians with expertise in pain, substance use disorders, and primary care conducted virtual meetings to review relevant literature and existing guidelines and share their clinical experience in UDM before reaching consensus recommendations.

Results

Definitive (e.g., chromatography-based) testing is recommended as most clinically appropriate for UDM because of its accuracy; however, institutional or payer policies may require initial use of presumptive testing (i.e., immunoassay). The rational choice of substances to analyze for UDM involves considerations that are specific to each patient and related to illicit drug availability. Appropriate opioid risk stratification is based on patient history (especially psychiatric conditions or history of opioid or substance use disorder), prescription drug monitoring program data, results from validated risk assessment tools, and previous UDM. Urine drug monitoring is suggested to be performed at baseline for most patients prescribed opioids for chronic pain and at least annually for those at low risk, two or more times per year for those at moderate risk, and three or more times per year for those at high risk. Additional UDM should be performed as needed on the basis of clinical judgment.

Conclusions

Although evidence on the efficacy of UDM in preventing opioid use disorder, overdose, and diversion is limited, UDM is recommended by the panel as part of ongoing comprehensive risk monitoring in patients prescribed opioids for chronic pain.

Evaluation of two enzyme immunoassays for the detection of the cocaine metabolite benzoylecgonine in 1,398 urine specimens

BACKGROUND

Benzoylecgonine (BE) is the primary urinary metabolite of cocaine. Two enzyme immunoassays were evaluated for the detection of BEin urine with a 300 ng/ml cutoff: the DRI® Cocaine Metabolite Assay and Lin-Zhi International's (LZ) Cocaine Metabolite Enzyme Immunoassay.

METHODS

This study involved 1,398 urine specimens from criminal justice and pain management programs. Gas chromatography/mass spectrometry (GC/MS) data were obtained for presumptive positives, and for negative urine specimens yielding responses significantly above the negative control.

RESULTS

Approximately 46% (644) of the specimens yielded positive results by DRI, and 47% (664) were positive by LZ. One specimen screened positive with both assays but was found to have a nondetectable BE concentration by GC/MS, indicating one false positive for each assay. Twenty-one specimens yielding negative DRIresults contained BEabove 300 ng/ml, and 29 specimens yielded false negatives with the LZassay. Therefore, the overall agreement between both immunoassays and GC/MSresults was 98%. Assay sensitivity was 0.968 (DRI) and 0.958 (LZ); the selectivity for both assays was 0.999. Urine specimens containing cocaine, additional cocaine metabolites, and other drugs were also tested. No cross-reactivity was observed.

CONCLUSION

Both the DRIand LZassays provide a precise, reliable method for the routine detection of BEin urine.

‘False-positive’ and ‘false-negative’ test results in clinical urine drug testing

The terms ‘false-positive’ and ‘false-negative’ are widely used in discussions of urine drug test (UDT) results. These terms are inadequate because they are used in different ways by physicians and laboratory professionals and they are too narrow to encompass the larger universe of potentially misleading, inappropriate and unexpected drug test results. This larger universe, while not solely comprised of technically ‘true’ or ‘false’ positive or negative test results, presents comparable interpretive challenges with corresponding clinical implications. In this review, we propose the terms ‘potentially inappropriate’ positive or negative test results in reference to UDT results that are ambiguous or unexpected and subject to misinterpretation. Causes of potentially inappropriate positive UDT results include in vivo metabolic conversions of a drug, exposure to nonillicit sources of a drug and laboratory error. Causes of potentially inappropriate negative UDT results include limited assay specificity, absence of drug in the urine, presence of drug in the urine, but below established assay cutoff, specimen manipulation and laboratory error. Clinical UDT interpretation is a complicated task requiring knowledge of recent prescription, over-the-counter and herbal drug administration, drug metabolism and analytical sensitivities and specificities.

Urine drug screening: practical guide for clinicians

Drug testing, commonly used in health care, workplace, and criminal settings, has become widespread during the past decade. Urine drug screens have been the most common method for analysis because of ease of sampling. The simplicity of use and access to rapid results have increased demand for and use of immunoassays; however, these assays are not perfect. False-positive results of immunoassays can lead to serious medical or social consequences if results are not confirmed by secondary analysis, such as gas chromatography-mass spectrometry. The Department of Health and Human Services' guidelines for the workplace require testing for the following 5 substances: amphetamines, cannabinoids, cocaine, opiates, and phencyclidine. This article discusses potential false-positive results and false-negative results that occur with immunoassays of these substances and with alcohol, benzodiazepines, and tricyclic antidepressants. Other pitfalls, such as adulteration, substitution, and dilution of urine samples, are discussed. Pragmatic concepts summarized in this article should minimize the potential risks of misinterpreting urine drug screens.

Drug screening and confirmation by GC–MS: Comparison of EMIT II and Online KIMS against 10 drugs between US and England laboratories

Drug screening through urinalysis is a widely accepted tool for rapid detection of potential drug use at a relatively low cost. It is, therefore, a potentially useful method for detecting and monitoring drug use in a variety of contexts such as the criminal justice system, pre-employment screening and a variety of treatment centers. This article explores the efficacy of two commercially available drug-screening assays: Online KIMS assay (Roche) and EMIT II assays. First, we evaluate the sensitivity and specificity of two immunoassays. A total of 738 urine samples were collected among adult arrestee populations from Chicago, New Orleans and Seattle through the Arrestee Drug Abuse Monitoring (ADAM) program. Partial samples were split within one laboratory and analyzed by both enzymes multiplied immunoassay technique (EMIT) II and kinetic interaction of microparticle in solution (KIMS) assays for a 10-drug panel (amphetamine, barbiturates, benzodiazepines, marijuana, cocaine, methadone, methaqualone, opiate, phencyclidine and propoxyphene). Gas chromatography-mass spectrometry (GC-MS) was used as a confirmation method for all positives from either EMIT II or KIMS for all experiments. Second, the paper examines whether using different testing laboratories plays a role in the final results. The same experiments were repeated at two different testing locations: one in California and one in London and England. Third, the paper studies whether drug testing results vary between two laboratories when each of them had used their own routine screening method: the Forensic Science Service (FSS) at Birmingham, United Kingdom with KIMS assay and Medscreen Limited at London, United Kingdom with EMIT II. In summary, both EMIT II and KIMS assays generate fairly consistent results. The concordance rate against each of the 10 drugs tested is relatively high (97.4-100%). The discrepancies, in most cases, occurred at drug concentrations near the cut-off levels. There were more discrepant results between two laboratories compared to when specimens were analyzed at the same laboratory using two different assays.

Hypothesis on interferences in kinetic interaction of microparticles in solution (KIMS) technology

The present paper describes an evaluation of the interferences found with an immunochemical drug test performed during a workplace control. During the period 1993–2003 more than 200,000 urine samples from workers were examined by the Italian Air Force. Samples were screened for drugs of abuse (opiates, cocaine, cannabinoids, amphetamines, methadone) using an immunochemical technique (Roche, kinetic interaction of microparticles in solution, KIMS). A total of 520 positive samples were sent to the Forensic Toxicology Laboratory for confirmation by gas chromatography/mass spectrometry (GC/MS). Approximately 39% of these were found to be true positives. For the remaining samples, pharmacological therapy in subjects was estimated to evaluate possible interferences due to medicine intake. Our study showed a high frequency of false-positive results with this immunochemical technique, mainly for the cannabinoid and amphetamine groups. Recurrent references to some medicines during subject anamnesis were noted.

Clin Chem Lab Med 2006;44;894–7.

Detection of drug use during pregnancy

Several methods of drug testing are efficacious in identifying and monitoring drug use during pregnancy. Urine screening remains the most commonly used method despite the limited period during which drugs can be detected. Hair has been recognized as a possible alternate test specimen, but wider acceptance of hair testing must await better understanding of drug disposition in hair, answers to the issues relating to interpretation, and the development of less demanding laboratory techniques. Regardless of the matrix used, proper interpretation of the results of drug testing requires familiarity with the sensitivity, specificity, and limitations of the laboratory methodologies employed. Moreover, unconfirmed positive results may actually be false-positives and must be interpreted with caution, particularly if they are the basis for major clinical decisions.

Screening for drugs of abuse (II): Cannabinoids, lysergic acid diethylamide, buprenorphine, methadone, barbiturates, benzodiazepines and other drugs

Requirements for the provision of an efficient and reliable service for drugs of abuse screening in urine have been summarized in Part I of this review. The requirements included rapid turn-around times, good communications between requesting clinicians and the laboratory, and participation in quality assessment schemes. In addition, the need for checking/confirmation of positive results obtained for preliminary screening methods was stressed. This aspect of the service has assumed even greater importance with widespread use of dip-stick technology and the increasing number of reasons for which drug screening is performed. Many of these additional uses of drug screening have possible serious legal implications, for example, screening school pupils, professional footballers, parents involved in child custody cases, persons applying for renewal of a driving licence after disqualification for a drug-related offence, doctors seeking re-registration after removal for drug abuse, and checking for compliance with terms of probation orders; as well as pre-employment screening and work-place testing. In many cases these requests will be received from a general practitioner or drug clinic with no indication of the reason for which testing has been requested. This also raises the serious problems of a chain of custody, provision of two samples, stability of samples, and secure and lengthy storage of samples in the laboratory-samples may be requested by legal authorities several months after the initial testing. The need for confirmation of positive results is now widely accepted but it may be equally important to confirm unexpected negative results. Failure to detect the presence of maintenance drugs may lead to the patient being discharged from a drug treatment clinic and, if attendance at the clinic is one of the terms of continued employment, to dismissal. It seems likely that increasing abuse of drugs and the efforts of regulatory authorities to control this, will lead to the manufacture of more designer drugs. Production of substituted phenethylamines was facilitated by the drug makers' cook book, 'PIHKAL' (Phenethylamines I Have Known And Loved) by Dr Alexander Shulgin and Ann Shulgin, and production of substituted tryptamines is promised in their next book, TIHKAL. Looking to the future, laboratories will need to ensure that they can detect and quantitate an ever-increasing number of drugs and related substances. The question of confidence in results of drugs of abuse testing raised in 1993 by Watson has assumed even greater importance as a result of attention focused on the OJ Simpson trial in Los Angeles. Toxicological investigations are likely to be challenged more frequently in the future. Even if analyses have been performed by GC-MS, there is a need to establish the level of match between the spectrum of the unknown substance and a library spectrum which is considered acceptable for legal purposes. It will also be essential to ensure that computer libraries contain spectra for all substances likely to be encountered in drugs of abuse screening.

Compulsory random drug testing of prisoners in England and Wales: design flaws in the system

The Home Office has recently introduced compulsory testing of prisoners in England and Wales for drug abuse. From 1996 all prisons in the UK will be involved. Urine samples from approximately 10% of the prison population will be collected each month. The method of drug analysis selected by the Home Office is fast and economical but readily prone to interference from common substances giving false results. An elaborate procedure has therefore been evolved including a rigorous personal search of the prisoner to prevent sample adulteration. The definitive test gas chromotography - mass spectrometry (GC-MS), is more expensive but is resistant to sample adulteration, and currently all positive samples are confirmed by this method. In view of the proportion of samples that have tested positive, the extent of the unknown number of false negatives, and the possible rejection of the collection protocol by prisoners, savings could be made if the method of analysis employed in the first instance was GC-MS. This paper illustrates the inaccuracies produced in an assay technique similar to that used by the Home Office when urine is contaminated by simple, commonly available substances.