Evaluation of a Urine On-Site Drugs of Abuse Screening Test in Patients Admitted to a Psychiatric Emergency Unit

The objective of this study was to characterize the usefulness and reliability of a commonly used urinary on-site drugs of abuse screening test device when used routinely at admittances to a psychiatric emergency unit. Urine samples from 262 emergency psychiatric admittances representing 217 patients were analyzed by a commercially available on-site test for the detection of amphetamines, benzodiazepines, cannabis, cocaine, and opiates in urine. The samples were first screened by nurses at the psychiatric department, thereafter by 2 technicians at the laboratory, and finally, analyzed by liquid chromatography/mass spectrometry. Results of 45.8% of the screening tests were true negative for all 5 drugs/drug groups tested, whereas those of 29.4% were true positive for 1 or several drugs/drug groups and true negative for the others. Thus, in total, 75.2% were correct for all 5 drugs/drug groups. In general, the sensitivities (42.9%-90.0% for the various drug groups) were lower than the specificities (92.7%-100.0%). The accuracies were 86.3% for benzodiazepines, 92.4% for cannabis, 94.7% for opiates, and 97.0% for amphetamines. No cocaine was found in any of the samples. For cannabis, the accuracy was higher among the laboratory technicians than among the nurses. The results from on-site screening testing should not be considered as the final conclusion on the intake of drugs of abuse but must be interpreted with caution.