543 - Let's Hash This Out: The case for Rapid THC Testing to Reduce ED Resource Utilization

Publication Number: 543.5666

Amanda S. Dupont, Medical College of Wisconsin, Mequon, WI, United States; Danny Thomas, Medical College of Wisconsin, milwaukee, WI, United States; Stanley Lo, Medical College of Wisconsin, Milwaukee, WI, United States; Kaitlyn E. Zakszewski, Medical College of Wisconsin, Wauwatosa, WI, United States; Michelle L. Reeves, Children's Hospital of Wisconsin, Milwaukee, WI, United States; Patrick S. Walsh, Medical College of Wisconsin, Milwaukee, WI, United States

Background: Rates of THC ingestion in pediatric emergency departments (ED) have increased dramatically in recent years. These children often present to the ED with unexplained altered mental status (AMS), which can lead to extensive diagnostic testing. Without a history of ingestion, diagnosis of THC intoxication is often delayed, particularly as urine drug screens take over an hour to result. Access to bedside point of care (POC) THC testing would potentially decrease time to diagnosis resulting in a decrease of unnecessary invasive workup for these children.

Objective: Establish sensitivity and specificity of POC urine THC test, comparing with a standard urine drug screen.

Design/Methods: This single center, prospective, 12-month observational study uses discarded urine specimens from children less than 18 years of age that have a urine drug screen ordered as standard of care during workup in the ED or during hospital admission. After gold standard urine drug testing was performed, the lab technician ran the POC THC test on the surplus urine. The gold standard urine drug screen detects THC at 20ng/ml. The POC test detects THC levels at 20ng/ml, 50ng/ml, 100ng/ml, and 200ng/ml. Prior data indicates that roughly 30% of urine samples are positive for THC. We used 300 and 700 patients for establishing sensitivity and specificity of POC testing, respectively, with a 95% confidence interval.

Results: We have collected 476 THC tests out of the 1,000 predicted samples. Of the 476 tests there are 121 true positives, 314 true negatives, 2 false positives, and 33 false negative. Based on the current data, intermediate analysis found the study POC THC test to have a specificity of 99.4% and a sensitivity of 78.6%. To date, 17% of the samples were rerun due to failure to meet control standards.

Conclusion(s): In this preliminary analysis, the American Screening Corp POC THC test demonstrated excellent specificity and moderate sensitivity for THC poisoning compared with our standard urine drug screen. There are some challenges in technical completion of the tests. This POC test could potentially be implemented in the ED to improve time-to-diagnosis of THC intoxication and reduce unnecessary diagnostic testing.