An assessment of oral fluid drug screening devices

Diagnostic accuracy for self-reported methamphetamine use versus oral fluid test as the reference standard in a methamphetamine-dependent intervention trial population

AIMS

Treatment of methamphetamine dependence requires monitoring of recent use or abstinence. Self-report is commonly used for routine monitoring, but the accuracy of self-report is not established. For the treating clinician, the key accuracy statistic is the negative predictive value (NPV). The study aim was to estimate the NPV of self-reported non-use of methamphetamine compared with an oral fluid reference standard.

DESIGN, SETTING AND PARTICIPANTS

This study was a secondary (subgroup) analysis from a randomized controlled pharmacotherapy trial. Three Australian outpatient addiction services took part. Particpants were 139 people dependent on methamphetamine.

MEASUREMENTS

Weekly oral fluid samples over 12 weeks to determine methamphetamine (and amphetamine) concentrations were used as the reference standard. Self-report of any methamphetamine use in the previous 7 days by the time-line follow-back method was the index test. Standard diagnostic accuracy statistics were calculated for all available paired episodes (n = 1134). Three NPV values were calculated: unadjusted NPV and NPV adjusted for clustering of observations through logistic regression and generalized estimating equation (GEE). We also calculated the NPVs for a range of prevalence rates of methamphetamine use, for the calculated levels of sensitivity and specificity.

FINDINGS

Sensitivity was 96.4% [95% confidence interval (CI) = 95-97.5], specificity was 63.7% (95% CI = 57.3-69.8) and positive predictive value (PPV) was 90.8% (95% CI = 88.8-92.6). The unadjusted NPV was 82.7% (95% CI = 76.5-87.9), adjusted NPV by logistic regression 82.7% (95% CI = 73.9-91.5) and GEE 76.8% (95% CI = 66.8-86.8). At a methamphetamine use prevalence of 5%, the estimated NPV would be 99.7% (95% CI = 99.6-99.9) and at 95% prevalence, 48.2% (95% CI = 39.6-57.0).

CONCLUSIONS

Self-report of no recent methamphetamine use appears to be sufficiently accurate to be clinically useful at the expected prevalence rates of methamphetamine use in clinical treatment settings. If generalizable to clinical settings, where these tests are routinely conducted, this may permit a reduction in the frequency and cost of oral fluid assays.

Saliva, a bodily fluid with recognized and potential diagnostic applications

Human whole saliva is a bodily fluid that can be obtained easily by noninvasive techniques. Specimens can be collected by the patient also at home in order to monitor health status and variations of several analytes of clinical interest. The contributions to whole saliva include secretions from salivary glands and, among others, from the gingival crevicular fluid that derives from the epithelial mucosa. Therefore, saliva is currently a relevant diagnostic fluid for many substances, including steroids, nonpeptide hormones, therapeutic drugs, and drugs of abuse. This review at first briefly describes the different contributions to whole saliva. A section illustrates the procedures for the collection, handling, and storage of salivary specimens. Another section describes the present use of whole saliva for diagnostic purposes and its specific utilization for the diagnosis of several local and systemic diseases. The final sections illustrate the future opportunities offered by various not conventional techniques with a focus on the most recent –omic investigations. It describes the various issues that have to be taken into account to avoid false positives and negatives, such as the strength of the experimental plan, the adequacy of the number of samples under study, and the proper choice of controls.

Prescription medication use as a risk factor for motor vehicle collisions: a responsibility study

INTRODUCTION

Previous studies on the effect of prescription medications on MVCs are sparse, not readily applicable to real-world driving and/or subject to strong selection bias. This study examines whether the presence of prescription medication in drivers' blood is associated with being responsible for MVC.

METHODS

This modified case-control study with responsibility analysis compares MVC responsibility rates among drivers with detectable levels of six classes of prescription medications (anticonvulsants, antidepressants, antihistamines, antipsychotics, benzodiazepines, opioids) versus those without. Data were collected between January 2010 and July 2016 from emergency departments in British Columbia, Canada. Collision responsibility was assessed using a validated and automated scoring of police collision reports. Multivariable logistic regression was used to determine OR of responsibility (analysed in 2018-2019).

RESULTS

Unadjusted regression models show a significant association between anticonvulsants (OR 1.92; 95% CI 1.20 to 3.09; p=0.007), antipsychotics (OR 5.00; 95% CI 1.16 to 21.63; p=0.03) and benzodiazepines (OR 2.99; 95% CI 1.56 to 5.75; p=0.001) with collision responsibility. Fully adjusted models show a significant association between benzodiazepines with collision responsibility (aOR 2.29; 95% CI 1.16 to 4.53; p=0.02) after controlling for driver characteristics, blood alcohol and Δ-9-tetrahydrocannabinol concentrations, and the presence of other prescription medications. Antidepressants, antihistamines and opioids exhibited no significant associations.

CONCLUSION

There is a moderate increase in the risk of a responsible collision among drivers with detectable levels of benzodiazepines in blood. Physicians and pharmacists should consider collision risk when prescribing or dispensing benzodiazepines. Public education about benzodiazepine use and driving and change to traffic policy and enforcement measures are warranted.

Thermographic detection and quantification of THC in oral fluid at unprecedented low concentrations

With recent changes in the legalization of cannabis around the world, there is an urgent need for rapid, yet sensitive, screening devices for testing drivers and employees under the influence of cannabis at the roadside and at the workplace, respectively. Oral fluid lateral flow immunoassays (LFAs) have recently been explored for such applications. While LFAs offer on-site, low-cost and rapid detection of tetrahydrocannabinol (THC), their nominal detection threshold is about 25 ng/ml, which is well above the 1-5 ng/ml per se limits set by regulations. In this paper, we report on the development of a thermo-photonic imaging system that utilizes the commercially available low-cost LFAs but offers detection of THC at unprecedented low concentrations. Our reader technology examines photothermal responses of gold nanoparticles (GNPs) in LFA through lock-in thermography (LIT). Our results (n = 300) suggest that the demodulation of localized surface plasmon resonance responses of GNPs captured by infrared cameras allows for detection of THC concentrations as low as 2 ng/ml with 96% accuracy. Quantification of THC concentration is also achievable with our technology through calibration.

Assessing the validity of eyelid parameters to detect impairment due to benzodiazepines

OBJECTIVE

Benzodiazepines impair driving ability and psychomotor function. Eyelid parameters accurately reflect drowsiness; however, the effects of benzodiazepines on these measures have not been extensively studied. The aim of this study was to investigate the effect of benzodiazepines on eyelid parameters and evaluate their accuracy for detecting psychomotor impairment.

METHODS

Eyelid parameters were recorded during a psychomotor vigilance task (PVT) and driving simulation over 2 days, baseline, and after 20-mg oral temazepam. The utility of eyelid parameters for detecting PVT lapses was evaluated using receiver operating characteristic curves, and cut-off levels indicating impairment (≥1 and ≥2 PVT lapses per min) were identified. The accuracy of these cut-off levels for detecting driving simulator crashes was then examined.

RESULTS

PVT and driving simulator performance was significantly impaired following benzodiazepine administration (p < .05). Average eyelid closure duration (inter-event duration) was a reliable indicator of PVT lapses (area under the curve [AUC] of 0.87-0.90). The cut-off value of eyelid closure duration derived from PVT AUC was able to predict driving simulator crashes with moderately high sensitivity and specificity (76.23% and 75.00%).

CONCLUSIONS

Eyelid parameters were affected by benzodiazepines and accurately detected the psychomotor impairment. In particular, eyelid closure duration is a promising real-time indicator of benzodiazepine impairment.

Prevalence of illicit substance use among patients presenting to the emergency department with acute behavioural disturbance: Rapid point-of-care saliva screening

OBJECTIVE

To determine the prevalence of illicit substance use among patients presenting to one ED with acute behavioural disturbance using point-of-care saliva testing.

METHODS

A prospective observational study was conducted. Acute behavioural disturbance was defined as any episode requiring a security response for unarmed threat (Code Grey). The setting was a single ED and tertiary referral centre located in metropolitan Australia. Participants were adults presenting to the ED requiring a Code Grey. Saliva was analysed for meth/amphetamine, cannabis, cocaine and opiates using a rapid point-of-care test. Self-reported drug use was recorded at the time of saliva testing. Data collection occurred between August 2016 and March 2017.

RESULTS

There were 229 valid saliva samples. Participants were, on average, 35 years (range 18-72) and male (168/229; 73%). Forty percent (95% confidence interval 34-47) of samples tested positive, with 20% positive for two or more substances. Meth/amphetamines was detected in 92% of positive samples, 17% of samples tested positive for opiates, 8% for cannabis and 7% for cocaine. Among participants, 19% self-reported current substance use and 20% reported using illicit substances within the past 24 h.

CONCLUSIONS

The prevalence of illicit substance use among this cohort was 40%. Self-reporting was unreliable. Point-of-care saliva testing is feasible. Early identification of harmful drug use may assist clinical decision making in selected or undifferentiated cases and provide an opportunity to implement harm minimisation strategies and make referrals.

Spectroelectrochemical and computational studies of tetrahydrocannabinol (THC) and carboxy-tetrahydrocannabinol (THC-COOH)

Electrochemical SERS allows for the rapid detection of both THC and THC-COOH in bodily fluid matrices without interferences from matrix species, paving the way to a point-of-need tool for cannabinoid detection.

Oral Fluid Drug Testing: Analytical Approaches, Issues and Interpretation of Results

With advances in analytical technology and new research informing result interpretation, oral fluid (OF) testing has gained acceptance over the past decades as an alternative biological matrix for detecting drugs in forensic and clinical settings. OF testing offers simple, rapid, non-invasive, observed specimen collection. This article offers a review of the scientific literature covering analytical methods and interpretation published over the past two decades for amphetamines, cannabis, cocaine, opioids, and benzodiazepines. Several analytical methods have been published for individual drug classes and, increasingly, for multiple drug classes. The method of OF collection can have a significant impact on the resultant drug concentration. Drug concentrations for amphetamines, cannabis, cocaine, opioids, and benzodiazepines are reviewed in the context of the dosing condition and the collection method. Time of last detection is evaluated against several agencies' cutoffs, including the proposed Substance Abuse and Mental Health Services Administration, European Workplace Drug Testing Society and Driving Under the Influence of Drugs, Alcohol and Medicines cutoffs. A significant correlation was frequently observed between matrices (i.e., between OF and plasma or blood concentrations); however, high intra-subject and inter-subject variability precludes prediction of blood concentrations from OF concentrations. This article will assist individuals in understanding the relative merits and limitations of various methods of OF collection, analysis and interpretation.

User experience and operational feasibility of four point-of-collection oral fluid drug-testing devices according to Brazilian traffic agents

OBJECTIVE

Traffic fatalities in Brazil still rank among the highest worldwide, with an overall rate of 23.4 deaths/100,000 inhabitants/year. Although alcohol and drug use play an important role in traffic accidents, national data about their relative influence are scarce. Drug screening is not routinely performed by traffic agents because alcohol is the only substance regularly investigated in roadblocks. Therefore, we aimed to describe the initial traffic agent user experience for 4 handheld point-of-collection oral fluid drug testing devices used in routine roadblocks in Brazil, focusing on usage perceptions in hopes of generalizing this approach for other developing countries.

METHODS

Four different oral fluid collection devices were evaluated: The DDS2, the DOA MultiScreen, the Dräger DrugTest 5000, and the Multi-Drug Multi-Line Twist Screen Device. Fourteen trained traffic agents obtained oral fluid from 164 drivers and performed 37 qualitative evaluations of the devices. Traffic agents filled out a questionnaire focusing on 9 feasibility criteria: Overall simplicity for roadside operation; operational success; saliva sample collection time; sample analysis time; ease of sample preparation and analysis; agreement with observed clinical signs; overall hygiene and safety; sufficient operating instructions; and hygiene of saliva collection. These were weighted based on an expert panel and yielded an overall composite device experience score that ranged from 1 (poor) to 100 (excellent).

RESULTS

Ease of use, operational success, and acceptable collection and analysis time were considered the most important criteria by the expert panel. The results ranged from 27.3 to 88.9% for simplicity of use; 45.5 to 100.0% for operational success; 27.3 to 100% for acceptable collection time; and 36.4 to 100.0% for acceptable analysis time. The final device scores, based on the agents' user experiences, ranked as follows: DOA MultiScreen: 49.3/100; Dräger DrugTest 5000: 82.4/100; Multi-Drug Multi-Line Twist Screen Device: 84.3/100; DDS2: 88.4/100.

CONCLUSION

Based on the selected criteria, 3 of the 4 devices were considered useful by traffic agents in routine roadblock operations. The weighted evaluations suggest that their ease of use (handling, sampling analysis, and reliability), as well as their agreement with findings obtained by other means, defined their utility to traffic agents, although such appraisals must be further analyzed in future studies.

Microfluidic electrochemical immunosensor for the trace analysis of cocaine in water and body fluids

Quick but accurate testing and on-the-spot monitoring of cocaine in oral fluids and urine continues to be an important toxicological issue. In terms of drug testing, a number of devices have been introduced into the market in recent decades, notably for workplace inspection or roadside testing. However, these systems do not always fulfill the requirements in terms of reliability, especially when low cut-off levels are required. With respect to surface water, the presence of anthropogenic small organic molecules such as prescription and over-the-counter pharmaceuticals as well as illicit drugs like cannabinoids, heroin, or cocaine, has become a challenge for scientists to develop new analytical tools for screening and on-site analysis because many of them serve as markers for anthropogenic input and consumer behavior. Here, a modular approach for the detection of cocaine is presented, integrating an electrochemical enzyme-linked immunosorbent assay (ELISA) performed on antibody-grafted magnetic beads in a hybrid microfluidic sensor utilizing flexible tubing, static chip and screen-printed electrode (SPE) elements for incubation, recognition, and cyclic voltammetry measurements. A linear response of the sensor vs. the logarithm of cocaine concentration was obtained with a limit of detection of 0.15 ng/L. Within an overall assay time of 25 minutes, concentrations down to 1 ng/L could be reliably determined in water, oral fluids, and urine, the system possessing a dynamic working range up to 1 mg/L.