Restraint in police use of force events: examining sudden in custody death for prone and not-prone positions.

Little is understood about the incidence of sudden death, its underlying pathophysiology, or its actual relationship to subject positioning. We report data from 4828 consecutive use of force events (August 2006-March 2013) in 7 Canadian police agencies in Eastern and Western Canada. Consecutive subjects aged >18 years who were involved in a police use of force event were included regardless of outcome. Officers prospectively documented: final resting position of the subject (prone or non-prone), intoxicants and/or emotional distress, presence of features of excited delirium, and the use of all force modalities. Our outcome of interest was sudden in-custody death. Our study has 80% power to detect a difference of 0.5% in sudden death between the positions. In over 3.25 million consecutive police--public interactions; use of force occurred in 4,828 subjects (0.1% of police public interactions; 95% CI = 0.1%, 0.1%). Subjects were usually male (87.5%); median age 32 years; 81.5% exhibited alcohol and/or drug intoxication, and/or emotional distress at the scene. Significantly more subjects remained in a non-prone vs. prone position; but over 2000 subjects remained prone. One individual died suddenly and unexpectedly in the non-prone position with all 10 features of excited delirium. No subject died in the prone position. There was no significant difference in sudden in custody death, in a worst case scenario 99.8% of subjects would be expected to survive being in either the prone or non-prone position following police use of force.