title: Incidence of psychotic disorders among first-generation immigrants and refugees in Ontario.
abstract: BACKGROUND
  Evidence suggests that migrant groups have an increased risk of psychotic disorders and that the level of risk varies by country of origin and host country. Canadian evidence is lacking on the incidence of psychotic disorders among migrants. We sought to examine the incidence of schizophrenia and schizoaffective disorders in first-generation immigrants and refugees in the province of Ontario, relative to the general population.
  
  
  METHODS
  We constructed a retrospective cohort that included people aged 14-40 years residing in Ontario as of Apr. 1, 1999. Population-based administrative data from physician billings and hospital admissions were linked to data from Citizenship and Immigration Canada. We used Poisson regression models to calculate age- and sex-adjusted incidence rate ratios (IRRs) and 95% confidence intervals (CIs) for immigrant and refugee groups over a 10-year period.
  
  
  RESULTS
  In our cohort (n = 4,284,694), we found higher rates of psychotic disorders among immigrants from the Caribbean and Bermuda (IRR 1.60, 95% CI 1.29-1.98). Lower rates were found among immigrants from northern Europe (IRR 0.50, 95% CI 0.28-0.91), southern Europe (IRR 0.60, 95% CI 0.41-0.90) and East Asia (IRR 0.56, 95% CI 0.41-0.78). Refugee status was an independent predictor of risk among all migrants (IRR 1.27, 95% CI 1.04-1.56), and higher rates were found specifically for refugees from East Africa (IRR 1.95, 95% CI 1.44-2.65) and South Asia (IRR 1.51, 95% CI 1.08-2.12).
  
  
  CONCLUSIONS
  The differential pattern of risk across ethnic subgroups in Ontario suggests that psychosocial and cultural factors associated with migration may contribute to the risk of psychotic disorders. Some groups may be more at risk, whereas others are protected.
authors.affiliation: Departments of Epidemiology and Biostatistics, and Psychiatry (Anderson), Western University, London Ont.; Institute for Clinical Evaluative Sciences (Anderson, Cheng, Kurdyak), Toronto, Ont.; Centre for Addiction and Mental Health (Cheng, McKenzie, Kurdyak), Toronto, Ont.; Mailman School of Public Health (Susser), Columbia University, New York, NY; Department of Psychiatry (McKenzie, Kurdyak), University of Toronto, Toronto, Ont. kelly.anderson@schulich.uwo.ca.
authors.forename: Kelly K
authors.initials: KK
authors.lastname: Anderson
authors.affiliation: Departments of Epidemiology and Biostatistics, and Psychiatry (Anderson), Western University, London Ont.; Institute for Clinical Evaluative Sciences (Anderson, Cheng, Kurdyak), Toronto, Ont.; Centre for Addiction and Mental Health (Cheng, McKenzie, Kurdyak), Toronto, Ont.; Mailman School of Public Health (Susser), Columbia University, New York, NY; Department of Psychiatry (McKenzie, Kurdyak), University of Toronto, Toronto, Ont.
authors.forename: Joyce
authors.initials: J
authors.lastname: Cheng
authors.affiliation: Departments of Epidemiology and Biostatistics, and Psychiatry (Anderson), Western University, London Ont.; Institute for Clinical Evaluative Sciences (Anderson, Cheng, Kurdyak), Toronto, Ont.; Centre for Addiction and Mental Health (Cheng, McKenzie, Kurdyak), Toronto, Ont.; Mailman School of Public Health (Susser), Columbia University, New York, NY; Department of Psychiatry (McKenzie, Kurdyak), University of Toronto, Toronto, Ont.
authors.forename: Ezra
authors.initials: E
authors.lastname: Susser
authors.affiliation: Departments of Epidemiology and Biostatistics, and Psychiatry (Anderson), Western University, London Ont.; Institute for Clinical Evaluative Sciences (Anderson, Cheng, Kurdyak), Toronto, Ont.; Centre for Addiction and Mental Health (Cheng, McKenzie, Kurdyak), Toronto, Ont.; Mailman School of Public Health (Susser), Columbia University, New York, NY; Department of Psychiatry (McKenzie, Kurdyak), University of Toronto, Toronto, Ont.
authors.forename: Kwame J
authors.initials: KJ
authors.lastname: McKenzie
authors.affiliation: Departments of Epidemiology and Biostatistics, and Psychiatry (Anderson), Western University, London Ont.; Institute for Clinical Evaluative Sciences (Anderson, Cheng, Kurdyak), Toronto, Ont.; Centre for Addiction and Mental Health (Cheng, McKenzie, Kurdyak), Toronto, Ont.; Mailman School of Public Health (Susser), Columbia University, New York, NY; Department of Psychiatry (McKenzie, Kurdyak), University of Toronto, Toronto, Ont.
authors.forename: Paul
authors.initials: P
authors.lastname: Kurdyak
mesh_terms: D000293:Adolescent; D000328:Adult; D054242:Emigrants and Immigrants / Q000523:psychology* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D009864:Ontario / Q000453:epidemiology; D011618:Psychotic Disorders / Q000453:epidemiology*; D012036:Refugees / Q000523:psychology* / Q000706:statistics & numerical data; D012189:Retrospective Studies; D012959:Socioeconomic Factors; D055815:Young Adult