title: The association between neighborhood effects and out-of-hospital cardiac arrest outcomes.
abstract: To date, 72% of variability in survival following out-of-hospital cardiac arrest (OHCA) is explained by the Utstein variables. Whether neighborhood factors further influence a return of spontaneous circulation or survival after OHCA is poorly understood.
  
  
  
  We completed a retrospective cohort study of all paramedic-treated OHCA within the City of Toronto's 531 census tracts between 2006 and 2014. Neighborhood variables included the Ontario Marginalization Index - a measure of poverty, ethnicity and instability - crime rate and the density of family physicians. Hierarchical logistic regression analysis explored the association between a patient's census tract (neighborhood) characteristics and survival to hospital discharge and a prehospital return of spontaneous circulation (ROSC). Receiver operator characteristics curves measured how the Utstein variables and neighborhood factors discriminate OHCA outcomes.
  
  
  
  There were 23,067 OHCA during the study period, with 10,097 cases excluded due to obvious death, 896 from an obvious etiology and 2589 cases for other reasons, leaving 9485 patients for analysis. Of the neighborhood variables, only census tracts with a moderate ethnic concentration had an increased likelihood of survival-to-hospital discharge. The Utstein variables accounted for 89.2% of survival and 39.8% of prehospital ROSC. Adding all neighborhood factors to the Utstein model increased discrimination for survival to discharge to 89.8% (p=0.005) and of a prehospital ROSC to 40.8% (p=0.006).
  
  
  
  Residential neighborhood factors marginally improve discrimination for outcomes after an OHCA, beyond the Utstein variables. Further research should explore the influence of other currently unmeasured neighborhood factors on OHCA outcomes.
authors.affiliation: Rescu, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Canada. Electronic address: buickJ@smh.ca.
authors.forename: Jason E
authors.initials: JE
authors.lastname: Buick
authors.affiliation: Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; Department of Medicine, University of Toronto, Toronto, Canada. Electronic address: rayJ@smh.ca.
authors.forename: Joel G
authors.initials: JG
authors.lastname: Ray
authors.affiliation: Institute of Health Policy, Management and Evaluation, Faculty of Medicine, University of Toronto, Toronto, Canada; Institute for Clinical and Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto, Canada. Electronic address: alex.kiss@ices.on.ca.
authors.forename: Alexander
authors.initials: A
authors.lastname: Kiss
authors.affiliation: Rescu, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; Division of Emergency Medicine, Department of Medicine, University of Toronto, Toronto, Canada. Electronic address: morrisonL@smh.ca.
authors.forename: Laurie J
authors.initials: LJ
authors.lastname: Morrison
mesh_terms: D000328:Adult; D000368:Aged; D016887:Cardiopulmonary Resuscitation / Q000401:mortality*; D016009:Chi-Square Distribution; D004632:Emergency Medical Services; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009864:Ontario / Q000453:epidemiology; D058687:Out-of-Hospital Cardiac Arrest / Q000401:mortality*; D010821:Physicians, Family / Q000600:supply & distribution; D012372:ROC Curve; D012111:Residence Characteristics; D012189:Retrospective Studies; D012931:Social Environment; D013997:Time Factors; D055815:Young Adult
keywords: Cardiopulmonary resuscitation; Geographic information systems; Heart arrest; Patients; Sudden death