Although rapid bedside toxicological screening is reliable, it has not been validated in the emergency department (ED) setting. We assessed the accuracy of a 10-min bedside immunoassay, Triage Panel (TP), for 7 drugs of abuse and
tricyclic antidepressants (TCA) in ED patients suspected of
drug toxicity. This was a prospective observational study conducted at an urban teaching ED (100,000 visits/year) of patients suspected of
drug toxicity during a 7-month period. The assay was compared for agreement with combined SYVA EMIT and TLC. GC/MS or HPLC was used for analyzing sensitivity and specificity in discordant findings. A total of 172 cases (ages 0.6-73 years) were screened with TP, and 100 (58%) were found to be positive for at least one
drug. Sensitivity (proportion and 95% CI) was as follows:
cocaine 30/31 (90.6-100%),
phencyclidine no cases,
THC 21/24 (80.1-94.3),
opiates 14/14 (100),
amphetamines 1/1 (NA),
barbiturates 10/10 (100),
benzodiazepines 20/21 (90.5-99.9), and TCA 13/13 (100). Specificity was above 98% for every
drug except TCAs (which was 95%), partly due to interference from
iminostilbene (a
carbamazepine metabolite) in three cases. Agreement between TP and hospital laboratory was over 90% for every
drug class. Both
benzodiazepines and
THC showed significant disagreement between the two testing modalities. In conclusion, in a series of ED patients suspected of
drug toxicity, the TP was an accurate tool to rule out the presence of seven drugs of abuse and TCAs. Further testing will be required to verify the efficacy of the test in populations with a higher prevalence of
phencyclidine and
amphetamine abuse.