title: A comprehensive assessment of health care utilization among homeless adults under a system of universal health insurance.
abstract: OBJECTIVE
  We comprehensively assessed health care utilization in a population-based sample of homeless adults and matched controls under a universal health insurance system.
  
  
  METHODS
  We assessed health care utilization by 1165 homeless single men and women and adults in families and their age- and gender-matched low-income controls in Toronto, Ontario, from 2005 to 2009, using repeated-measures general linear models to calculate risk ratios and 95% confidence intervals (CIs).
  
  
  RESULTS
  Homeless participants had mean rates of 9.1 ambulatory care encounters (maximum = 141.1), 2.0 emergency department (ED) encounters (maximum = 104.9), 0.2 medical-surgical hospitalizations (maximum = 14.9), and 0.1 psychiatric hospitalizations per person-year (maximum = 4.8). Rate ratios for homeless participants compared with matched controls were 1.76 (95% CI = 1.58, 1.96) for ambulatory care encounters, 8.48 (95% CI = 6.72, 10.70) for ED encounters, 4.22 (95% CI = 2.99, 5.94) for medical-surgical hospitalizations, and 9.27 (95% CI = 4.42, 19.43) for psychiatric hospitalizations.
  
  
  CONCLUSIONS
  In a universal health insurance system, homeless people had substantially higher rates of ED and hospital use than general population controls; these rates were largely driven by a subset of homeless persons with extremely high-intensity usage of health services.
authors.affiliation: Stephen W. Hwang, Catharine Chambers, and Shirley Chiu are with the Centre for Research on Inner City Health, part of the Keenan Research Centre in the Li Ka Shing Knowledge Institute at St. Michael's Hospital, Toronto, Ontario. Marko Katic and Alex Kiss are with the Department of Research Design and Biostatistics, Sunnybrook Health Sciences Centre, Toronto. Donald A. Redelmeier is with the Institute for Clinical Evaluative Sciences, Sunnybrook Health Sciences Centre, Toronto. Wendy Levinson is with the Department of Medicine, University of Toronto.
authors.forename: Stephen W
authors.initials: SW
authors.lastname: Hwang
authors.forename: Catharine
authors.initials: C
authors.lastname: Chambers
authors.forename: Shirley
authors.initials: S
authors.lastname: Chiu
authors.forename: Marko
authors.initials: M
authors.lastname: Katic
authors.forename: Alex
authors.initials: A
authors.lastname: Kiss
authors.forename: Donald A
authors.initials: DA
authors.lastname: Redelmeier
authors.forename: Wendy
authors.initials: W
authors.lastname: Levinson
mesh_terms: D000328:Adult; D000553:Ambulatory Care / Q000706:statistics & numerical data; D002170:Canada / Q000453:epidemiology; D015331:Cohort Studies; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006296:Health Services / Q000706:statistics & numerical data*; D006703:Ill-Housed Persons / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D008875:Middle Aged; D012959:Socioeconomic Factors; D014481:United States / Q000453:epidemiology; D019472:Universal Health Insurance