Evaluation of in-house drug evidence testing by King County Medical Examiner's Office in “real-time” fatal overdose surveillance

With the escalating overdose epidemic, many surveillance efforts have appeared. In 2018, King County Medical Examiner's Office (KCMEO) initiated a fatal overdose surveillance project aimed at expediting death certification and disseminating timely information. In this project, KCMEO investigators collected items of evidence of drug use from overdose death scenes, which were tested by five in-house methods, four using handheld devices: TruNarc Raman spectrometer, with and without the manufacture's H-Kit, Rigaku ResQ Raman spectrometer, and MX908 mass spectrometer. The fifth in-house method used fentanyl-specific urine test strips. Results from in-house testing were compared with results from Washington State Patrol (WSP) Materials Analysis Laboratory. From 2019 to 2022, there were 4244 evidence items of drugs and paraphernalia collected from 1777 deaths scenes. A total of 7526 in-house tests were performed on collected specimens, and 2153 tests were performed by the WSP laboratory using standard analytical methods. The WSP results served as reference standards to calculate performance metrics of the in-house methods. Sensitivities, specificities, and predictive values ranged from good to poor depending on the method, drug, and evidence type. Certain drugs were often associated with specific evidence types. Acetaminophen was frequently found in combination with fentanyl. Fentanyl test strips gave good scores for detecting fentanyl; otherwise, in-house methods using handheld devices had poor performance scores with novel drugs and drugs diluted in mixtures. The results showed that in-house testing of drug evidence has value for medical examiner overdose surveillance, but it is resource intensive, and success depends on collaboration with forensic laboratories.