title: Remigration of migrants with severe disease: myth or reality?--a register-based cohort study.
abstract: BACKGROUND
  'Remigration bias' is often referred to when explaining low mortality outcomes among migrants compared with local-born. The hypothesis suggests that severely ill migrants tend to return to their country of origin, but it has hitherto not been tested in a large-scale epidemiological study. Consequently, we studied whether migrants with severe disease were more likely to emigrate compared with migrants without severe disease.
  
  
  METHODS
  A historic prospective cohort study was conducted based on all adult refugees and family reunification immigrants (n = 114,331) who obtained residence permission in Denmark between 1 January 1993 and 31 December 2010. Migrants with severe disease were identified through the Danish National Patient Register. Emigrations during follow-up (1 January 1993 to 31 December 2011) were identified using the Danish Civil Registration System. Hazard ratios were calculated for emigration among migrants with different levels of disease severity, adjusting for sex, age and income.
  
  
  RESULTS
  Results showed progressively fewer emigrations with increasing disease severity. Migrants with low (HR = 0.92; 95% CI: 0.80-1.06), moderate (HR = 0.84; 95% CI: 0.67-1.06) and high (HR = 0.70; 95% CI: 0.55-0.90) disease severity had fewer emigrations to 'country of origin' compared with migrants without disease. For emigration to 'any country', results likewise showed fewer emigrations among migrants with low (HR = 0.86; 95% CI: 0.78-0.95), moderate (HR = 0.73; 95% CI: 0.62-0.87) and high (HR = 0.64; 95% CI: 0.53-0.76) disease severity. This tendency was also observed by nationality and migrant status. On the disease-specific level, no uniform tendencies in emigration patterns were identified.
  
  
  CONCLUSIONS
  The results do not generally support the hypothesis of 'remigration bias' but rather suggest the opposite. Accordingly, remigration bias does not appear to explain lower mortality of migrants.
authors.affiliation: 1 Section for Health Services Research, Department of Public Health, Danish Research Centre for Migration, Ethnicity, and Health, University of Copenhagen, Copenhagen, Denmark 2 Department of Immigrant Medicine, Section of Infectious Diseases, Hvidovre Hospital, Copenhagen, Denmark mano@sund.ku.dk.
authors.forename: Marie
authors.initials: M
authors.lastname: Norredam
authors.affiliation: 3 Section for Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Oluf Hoejbjerg
authors.initials: OH
authors.lastname: Hansen
authors.affiliation: 3 Section for Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Jørgen Holm
authors.initials: JH
authors.lastname: Petersen
authors.affiliation: 4 Department of Public Health, Amsterdam Medical Centre, Amsterdam University, Amsterdam, The Netherlands.
authors.forename: Anton E
authors.initials: AE
authors.lastname: Kunst
authors.affiliation: 1 Section for Health Services Research, Department of Public Health, Danish Research Centre for Migration, Ethnicity, and Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Maria
authors.initials: M
authors.lastname: Kristiansen
authors.affiliation: 1 Section for Health Services Research, Department of Public Health, Danish Research Centre for Migration, Ethnicity, and Health, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Allan
authors.initials: A
authors.lastname: Krasnik
authors.affiliation: 4 Department of Public Health, Amsterdam Medical Centre, Amsterdam University, Amsterdam, The Netherlands.
authors.forename: Charles
authors.initials: C
authors.lastname: Agyemang
mesh_terms: D000328:Adult; D002908:Chronic Disease / Q000453:epidemiology*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012042:Registries / Q000706:statistics & numerical data*; D012720:Severity of Illness Index