Identifying Chicago's High Users of Police-Involved Emergency Services.

Abstract

To identify individuals at risk for behavioral health (BH)-involved encounters with police in Chicago, Illinois. We linked Chicago Police Department (CPD) arrest and Fire Department (CFD) BH-involved ambulance event data. We identified at-risk individuals who accumulated at least 1 BH-involved ambulance and at least 1 arrest event between May 2016 and April 2017. We identified a high-use subgroup displaying most intensive services use. We identified high-use locations with highest volume of ambulance events with only CFD data. Of 83 392 individuals and 116 105 events in the linked emergency events data, 1842 at-risk individuals accounted for 2.2% of individuals, 5.6% of all events, and 16% of BH-involved CFD events with police involvement. A total of 330 high-use individuals accounted for 0.4% of individuals, 2% of events, and 4.7% of CFD events with police involvement. Top-100 high-use locations accounted for 9% of CFD events, and individuals of high-use location events are largely distinct from high-use individuals. Integrated police and ambulance data hold promise to identify individuals at risk for BH-involved encounters with police and to support proactive interventions to prevent or improve response at these encounters.