Distinguishing features of Excited Delirium Syndrome in non-fatal use of force encounters

Study objective: The frequency with which the police encounter non-fatal cases of Excited Delirium Syndrome (ExDS) has not been well studied. To date only a single prospective, epidemiologic study has been completed to determine the prevalence of the features of ExDS in police use of force (UoF) encounters. We examined a cluster of previously published features associated with ExDS to establish if these features were consistently recognizable across policing populations, thus demonstrating reproducibility. We further sought to determine whether any feature or number of concomitant features were likely to have physiologic significance. These are important first steps in determining a case definition of ExDS in a law enforcement and medical setting. Methods: A prospective evaluation of a consecutive cohort of subjects involved in UoF encounters with police was conducted. Data were collected through the UoF reporting database of a large Canadian law enforcement agency from January, 2012 to December, 2013. The ten core characteristics of ExDS that have been observed in past research were documented by officers and, consistent with previous research, the presence of six or more features was used to identify probable cases of ExDS and a state of medical emergency. Results: UoF occurred in 4799 of 5.4 million policeepublic interactions (0.09%). Of the UoF encounters, 73 (1.5%) subjects displayed six or more features of ExDS. Upwards of 9.2% of these subjects could be expected to be at risk of sudden and unexpected arrest-related death (ARD). Features with the highest odds of being presented with a large number of concomitant features included "Does not Fatigue", "Superhuman Strength" and "Tactile Hyperthermia" (287, 137 and 93 times higher, respectively). Moreover, "Tactile Hyperthermia" demonstrated the highest odds of being presented in individuals with a large number of features as opposed to those with fewer (33 times higher). Conclusion: We demonstrate that there is the ability for law enforcement officers to consistently recognize and report features of ExDS that have been associated with ARD. The varying presence of features across the examined categories indicates that some features are more distinguishing than others, which may enable narrowing the scope of features that represent ExDS and understanding its pathophysiology. The current debate surrounding whether or not ExDS exists limits first responders and emergency physicians in their ability to increase awareness, improve training and interventions, and design appropriate policy and response protocols to reduce ARDs. Crown Copyright (C) 2016 Published by Elsevier Ltd. All rights reserved.