title: Hospitalizations due to allergic reactions in Finnish and Swedish children during 1999-2011.
abstract: Several authors have reported on allergic reactions that resulted in presentation to the emergency department. However, studies of the secular trend of hospitalizations for paediatric allergic reactions, including anaphylaxis, are scarce. The aim of this study was to describe the secular trends of hospitalizations for allergic reactions, including anaphylaxis, among children aged 0-19 years in Finland and Sweden, and to establish the trend of prescribed epinephrine auto-injectors (EAI) among paediatric populations.
  
  
  
  Using national databases, we identified hospitalizations between 1999 and 2011 with the primary diagnosis of allergic reaction per International Classification of Diseases, 10th Revision.
  
  
  
  Hospitalizations for allergic reactions totalled 1987 in Finland and 5433 in Sweden. Incidence rates increased in both countries. In Finland, the incidence of admission was 7.8 per 100 000 person-years at the start of the study period and 15.8 at the end of the study period. The corresponding numbers among Swedish children were 13.7 and 31.8 per 100 000 person-years. In Finland, 60% of children hospitalized were aged under 10 years. In Sweden, this proportion was somewhat lower, at 48%. Most hospitalizations occurred between May and September. The prevalence of EAI prescriptions in Finland increased by fourfold during the study period. In Sweden, such an increase was not identified.
  
  
  
  The incidence of allergic reactions leading to hospitalizations between 1999 and 2011 increased in Finland and Sweden among children aged 0 to 19 years. In Finland, the incidence was lower throughout the study period compared to Sweden. Younger children constituted the majority of hospitalized children.
authors.affiliation: Allergy Centre, Tampere University Hospital, Tampere, Finland.|Centre for Child Health Research, Tampere University and University Hospital, Tampere, Finland.|Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.
authors.forename: J E
authors.initials: JE
authors.lastname: Kivistö
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.|Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: J L P
authors.initials: JL
authors.lastname: Protudjer
authors.affiliation: Allergy Centre, Tampere University Hospital, Tampere, Finland.
authors.forename: J
authors.initials: J
authors.lastname: Karjalainen
authors.affiliation: Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.|Sachs' Children and Youth Hospital, Stockholm, Sweden.
authors.forename: M
authors.initials: M
authors.lastname: Wickman
authors.affiliation: Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden.|Centre for Allergy Research, Karolinska Institutet, Stockholm, Sweden.
authors.forename: A
authors.initials: A
authors.lastname: Bergström
authors.affiliation: Department of Orthopaedics, Tampere University Hospital, Tampere, Finland.|Department of Clinical Science, Intervention and Technology (CLINTEC), Division of Orthopedics and Biotechnology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: V M
authors.initials: VM
authors.lastname: Mattila
mesh_terms: D000293:Adolescent; D017677:Age Distribution; D002648:Child; D002675:Child, Preschool; D016208:Databases, Factual; D005260:Female; D005387:Finland / Q000453:epidemiology; D049673:History, 20th Century; D049674:History, 21st Century; D006760:Hospitalization; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology* / Q000266:history; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015995:Prevalence; D062486:Public Health Surveillance; D012621:Seasons; D013548:Sweden / Q000453:epidemiology
keywords: anaphylaxis; child; hospitalization; hypersensitivity