title: Differences in hospital attendance for anaphylaxis between immigrants and non-immigrants: a cohort study.
abstract: The impact of migration on the risk of anaphylaxis remains unknown. We hypothesized that non-Western immigrants have a lower incidence of anaphylaxis compared to Danish-born. We investigated variations in hospital attendance for anaphylaxis between immigrants and Danish-born including time- and age- trends.
  
  
  
  A register-based, historical prospective cohort design. Refugees or family reunified immigrants (n = 127 250) who, between January 1, 1994 and December 31, 2010, obtained residency permits in Denmark were included and matched in a 1 : 6 ratio on age and sex with Danish-born individuals (n = 740 600). Personal identification numbers were cross-linked to the Danish National Patient Registry identifying all first-time hospital attendances for anaphylaxis from January 1, 1994 and December 31, 2010. Incidence rate ratios were estimated, stratified for sex and region of birth, adjusting for age using a Cox regression model including the influence of duration of residence and age when residence was obtained.
  
  
  
  In total 1053 hospital attendances for anaphylaxis were identified: 89 among non-Western immigrants, 9 among Western immigrants and 955 among Danish-born patients. Both male (RR = 0.65; 95%CI: 0.46;0.90) and female (RR = 0.64; 95%CI: 0.48;0.85) non-Western immigrants had a significantly lower risk ratio of hospital attendance for anaphylaxis compared to Danish-born. Compared to Danish-born, non-Western immigrants living in Denmark during the entire follow-up period also showed a decreased risk (RR = 0.65; 95%CI: 0.34;1.25). Compared to Danish-born, non-Western immigrants who obtained residence permission as children had a decreased risk of hospital attendance for anaphylaxis (RR = 0.48; 95%CI: 0.25;0.91).
  
  
  
  This Danish register-based study using nationwide data revealed fewer hospital attendances for anaphylaxis among non-Western immigrants compared to Danish-born; however this protection was lost over time.
authors: Danish Research Centre for Migration, Ethnicity and Health, Section of Health Services Research, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.|Section of Immigrant Medicine, Department of Infectious Diseases, Copenhagen University Hospital, Hvidovre, Denmark.
authors: M
authors: M
authors: Norredam
authors: Allergy & Respiratory Research Group, Centre for Population Health Sciences, The University of Edinburgh, Edinburgh, UK.|Division of General Internal Medicine and Primary Care, Brigham and Women's Hospital/Harvard Medical School, Boston, MA, USA.
authors: A
authors: A
authors: Sheikh
authors: Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors: K
authors: K
authors: Dynnes Svendsen
authors: Section of Biostatistics, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors: J
authors: J
authors: Holm Petersen
authors: Allergy Clinic, Copenhagen University Hospital Gentofte, Copenhagen, Denmark.
authors: L H
authors: LH
authors: Garvey
authors: Center for Healthy Aging, Section of Health Services Research, Department of Public Health, University of Copenhagen, Copenhagen, Denmark.
authors: M
authors: M
authors: Kristiansen
mesh_terms: D000293:Adolescent; D000328:Adult; D000707:Anaphylaxis / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D054242:Emigrants and Immigrants / Q000706:statistics & numerical data*; D005260:Female; D054625:Healthcare Disparities / Q000706:statistics & numerical data*; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D012042:Registries; D012307:Risk Factors; D055815:Young Adult
keywords: allergy; anaphylaxis; hospital attendance; immigrants; migration