NA, not applicable or not available; MDMA, methylenedioxymethamplietamine.
NA, not applicable or not available; MDMA, methylenedioxymethamplietamine.
analytical criteria (Table 4). For oral fluid, the sensitivity of the on-site test devices and of some confirmation methods was very poor (Table 5). This was explained by the extremely low concentrations of benzodiazepines in oral fluid (often <1 ng/mL). This was even more so for the low levels of some benzo-diazepines, such as flunitrazepam. No on-site tests were available for sweat.
For cannabinoids, comparison of the performance of the different matrices showed a small advantage for oral fluid (89% accuracy; Table 3), which is not unexpected considering the much longer window of detection of cannabis metabolites in urine compared with the presence of tetrahydrocannabinol (THC) in blood. Three of 11 on-site tests for urine met the analytical criteria. These were Dipro, Cortez (Cortez Diagnostics), and SRT (Table 4). In comparison with blood, the accuracy of the best on-site urine tests was close to 90%. For the on-site oral-fluid tests (Table 5), the sensitivity was too low (only 18 to 25% when compared with blood results). The required sensitivity of on-site oral-fluid tests was 2 ng/mL of THC. There were indications that THC may bind to the material of some sampling devices. Much higher concentrations of THC could be extracted from the cotton of the Salivette®, in comparison with the THC concentrations in oral fluid. A possible explanation could be that the cotton of the Salivette absorbs the THC that has been sequestered onto teeth and gum, but this possibility needs to be confirmed. This phenomenon could be useful for increasing the sensitivity of oral-fluid analysis for THC, if a suitable extraction method can be found to release the THC trapped on the fibers of the sampling device. For testing of cannabinoids with sweat, no on-site test devices were available.
For cocaine and metabolites, both oral fluid and urine gave good correlation for the prediction of positive drug results in blood assessed by GC-MS (Table 3). Eight of the 11 on-site tests met the analytical criteria. These were Dipro, RDS, TesTcup (Roche Diagnostics.), Syva Rapid Cup (SRC), SRT, SureScreen™ (Surescreen Diagnostics), Status DS™ (Lifesign), and Triage (Table 4). Even when compared with blood results, four tests had an accuracy of greater than 95% and sensitivity and specificity greater than 90%: RDS, Roche TesTcup, SRT, and Triage. In oral fluid, the evaluation was hampered by the low number of positive samples (Table 5). In addition, the sensitivity of Drugwipe was too low. For sweat, the number of samples that could be evaluated was also small, and the evaluation was done with positive samples only. The accuracy of Drugwipe was 77% (Table 6).
When comparing the GC-MS analysis of opiates in different body fluids with the GC-MS analysis of blood samples, oral fluid had slightly better accuracy than urine (Table 3). Six of the 11 on-site tests met the analytical criteria (Table 4): RDS, Cortez, SRC, SRT, Status DS, and Triage. With oral fluid, the on-site tests showed less accuracy than with urine tests (Table 5). The sensi tivity, in particular, was too low. An ideal oral-fluid test should have a detection limit of 2-5 ng/mL for opiates.
When the necessary facilities were available (e.g., a sanitary van), urine could be obtained relatively easily at the roadside. When the facilities were not available, obtaining a urine sample was a problem, and it could be time-consuming if the driver had to be brought to a suitable facility. In some cases, the volume of urine obtained was low and was insufficient for certain test devices. Some countries clearly stated that sampling urine at the roadside was unacceptable. A clear majority of countries preferred oral fluid as the matrix for roadside testing, while one country favored sweat and one country favored urine. The methods for obtaining oral fluid needed further improvements. Wiping over the tongue seemed to be a well-accepted technique, but in this case the analytical detection technique needed to be very sensitive. Sampling oral fluid with dedicated devices also gave rise to the following problems:
• It was sometimes messy and uncomfortable for the subject;
• The cooperation of the subject was needed (in some cases, intentionally or not, the subject swallowed the collection device);
• Oral fluid was sometimes viscous and could not be used with some devices.
Moreover, dry mouth was a frequently encountered problem in drug users. Sampling was then even more difficult and time-consuming. However, in the present evaluation, obtaining oral fluid for testing was successful in nearly all cases. Overall, sweat and oral-fluid sampling seemed very well accepted by the subjects, much moreso than that of urine or blood.
Eleven different on-site test devices for detection of illegal drugs in urine were evaluated. Most of the urine test devices only reached accuracy levels of approx 90% when correlated with the blood results. This could be a result of the discrepancy in temporal distribution of drugs in different body fluids. A much better accuracy rate is reached when the urine results of roadside test devices are correlated with urine results from GC-MS analysis. In this case, several test devices surpass the 95% accuracy rate for some drug classes. However, some limitations of the study design, which is mainly dictated by the different legal situations, must be pointed out:
• The analytical methods used in all the countries were not identical; the evaluation of the devices was done in different places—at the roadside, in the police station, or in the laboratory;
• The devices were evaluated by different persons, which made their comments on the practical and operational aspects of the study difficult to compare;
• Prevalence of drug use and the selection criteria of the subjects differed among the countries, resulting in variability in the preferential use of different specimens for different on-site test devices in different countries.
In several countries, the ROSITA evaluations were the first experience that police officers had had with roadside drug tests and, despite some problems and disappointments, police officers still liked having the tools to detect drivers under the influence of drugs. Users of on-site tests had also shown great creativity in overcoming some of the encountered problems. The oral-fluid devices available at the time of the study all had practical disadvantages, and the analytical evaluation was not satisfactory. But the need for such devices was so great that in one country, police officers preferred to perform an oral-fluid test that was imperfect, rather than no test at all. In other countries, police would rather use urine tests. Police did not have major objections to collecting specimens. A majority of the countries favored oral fluid as a test matrix. Besides the analytical evaluation discussed here, all test devices that were part of the field trials had also been evaluated by the police with respect to handling, ease of sampling, speed, and overall user-friendliness.
In the "needs and requirements" survey, most police forces in Europe expressed preferences for test devices based on oral fluid or sweat because of the ready availability of the specimen. Interestingly, sampling urine during the field-test phase was not a problem, if appropriate facilities (such as a sanitary van) were available. In other cases, drivers had to be taken to a police station or health center, which took time. In one country, when drivers were asked to give a urine sample at the roadside without suitable facilities, the refusal rate was high. Most police forces in Europe are legally not authorized to obtain a urine sample by force. Sampling oral fluid or sweat was much more acceptable to drivers. The possibility of using sweat as a testing specimen is especially of interest to the police forces.
In some cases, the volume of urine collected was not sufficient for the cup-type test devices (e.g., SRC, TesTcup, RDS). This was a problem in 3% of the cases in Germany. In that respect, RDS has the advantage that the urine can be pipetted onto the card.
In some cases, the calculation of the different analytical criteria was hampered by the skewing of the data toward one end of the positive-negative spectrum. For example, many drivers have been tested with ORALscreen, but most of the results turn out to be negative, leading to good accuracy values despite the fact that sensitivity is insufficient. The accuracy of the on-site tests for oral fluid is not satisfactory when one compares it with the reference method in the same specimen: the sensitivity is between 25% (ORALscreen cannabinoids)
and 88% (Drugwipe amphetamines/MDMA). Specificity is in the range of 48% (RapiScan benzodiazepines) to 100% (RapiScan cocaine). Very high specificity values are again a result of no or very low numbers of positive samples. The performance of Drugwipe for amphetamines/MDMA and opiates in sweat seems good, but very few negative samples were analyzed. More studies will be needed to confirm these findings and to allow a proper evaluation of Drugwipe as a sweat test.
Benzodiazepines are present in oral fluids in extremely low concentrations. In a review by Kidwell (8), the limits of the methods used to detect benzodiazepines in oral fluid range from 0.05 to 5 ng/mL, with the majority being less than 0.3 ng/mL. At present, the sensitivity of the on-site test and of some confirmation methods is poor.
The sampling method for Drugwipe (wiping over the tongue) was appreciated everywhere, because of minimal discomfort and low sample-volume requirement. ORALscreen was considered "disgusting" in Germany and Scotland because of the many complications that occurred during sampling, and in nearly all cases, the fingers of the officers and researchers came into contact with oral fluid. This was certainly less acceptable to them than working with urine. Sampling with Cozart Rapiscan was also problematic. The process took a long time and was cumbersome. It was worse if drivers were able to provide only a limited volume of oral fluid, either because of low oral-fluid production or because of refusal to cooperate. The average duration of sampling with the Rapiscan was 4 min, with extremes between 1 and 12 min. Average total time for sampling plus analysis was 20 min (range was 13 to 33 min), which was considered too long for roadside use. One advantage of Cozart Rapiscan was the availability of excess (diluted) samples for performing confirmation tests in the laboratory. In the final analysis, sampling by wiping the tongue is well accepted, although this process requires a very sensitive detection method because of the low volume and the lack of sufficient sample for confirmation analysis. The other methods all have some drawbacks, and more research is needed to develop more efficient sampling methods.
In terms of practical use, none of the testing devices was fully acceptable to the police officers. In Germany, the acceptance of the oral-fluid tests was much less than any of the urine tests. Drugwipe was considered simple in terms of the training needed. The small sample volume and rapid turnaround time were appreciated; however, viewed less favorably were the availability of only single tests, the difficulty of reading of the results, and the need for water in order to perform the test. Use of the electronic reader was considered impractical in Norway, but was considered essential in all other countries. In Italy, oral fluid was considered quite easy to test at the roadside, at least through the use of Drugwipe.
With Avitar ORALscreen, problems were encountered in the transferal of oral fluid from the sampling device to the test. In Scotland, problems were encountered with the transfer of viscous oral fluid, and some samples failed to migrate to the analytical strip as a result of manufacturing faults. Some problems with reading the ORALscreen were reported. Faint lines were produced, especially for cannabinoids, resulting in difficulty in distinguishing presence or absence of drugs. The multiple pieces of equipment and the need to place them on a flat surface made the use of Cozart Rapiscan impractical for a police officer on a motorbike, and restricted its use to police officers driving a van. The equipment proved to be rather complicated to use, and the total time needed to obtain a result (sample collection, sample preparation, run time) was at least 15 min. Often, it took that long just to collect sufficient oral fluid from drivers under the influence of drugs, as they often had very dry mouth as a result of drug use. General comments from police officers were that the sample-preparation procedures (filtration, pipetting, and handling of sample tubes) were rather complicated, such that previous training in the laboratory was necessary.
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