title: Hospitalization rates and prognosis of patients with anaphylactic shock in Denmark from 1995 through 2012.
abstract: BACKGROUND
  Anaphylactic shock (AS) is an acute, potentially life-threatening hypersensitivity reaction. There are limited population-based data on changes in the hospitalization rate and prognosis of AS.
  
  
  OBJECTIVE
  We sought to examine the proportion of patients with AS admitted to an intensive care unit (ICU), the prognosis of AS, and time trends in AS hospitalization rates in Denmark from 1995 through 2012.
  
  
  METHODS
  We performed a population-based cohort study in Denmark from 1995 through 2012 (cumulative population, 7.1 million) using the Danish National Patient Registry and the Danish Civil Registration System. Outcomes included time trends in first-time AS hospitalization rates, percentage admitted to an ICU, and 30-day mortality overall and stratified by year.
  
  
  RESULTS
  We included 6,707 patients with a first-time hospitalization for AS during 103,747,997 person-years of observation time. The average AS hospitalization rate was 64.6 (95% CI, 63.1-66.2) per 1,000,000 person-years. From 1995 to 2012, the annual AS hospitalization rate increased more than 2-fold (rate ratio, 2.6; 95% CI, 2.2-3.0). However, the annual hospitalization rate in children increased 10-fold (rate ratio, 10.75; 95% CI, 5.59-20.67). Only 0.7% of patients died within 30 days after admission (50 deaths), and most fatal AS cases occurred among patients aged 30 years or older. During the 2005-2012 period, 14.5% of patients hospitalized with AS were admitted to an ICU.
  
  
  CONCLUSIONS
  The AS hospitalization rate increased from 1995 to 2012; however, the 30-day mortality was less than 1%.
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark; Research Centre of Emergency Medicine, Aarhus University Hospital, Aarhus, Denmark. Electronic address: anni.jeppesen@clin.au.dk.
authors.forename: Anni Nørgaard
authors.initials: AN
authors.lastname: Jeppesen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Christian Fynbo
authors.initials: CF
authors.lastname: Christiansen
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Trine
authors.initials: T
authors.lastname: Frøslev
authors.affiliation: Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Henrik Toft
authors.initials: HT
authors.lastname: Sørensen
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000707:Anaphylaxis / Q000453:epidemiology*; D002648:Child; D002675:Child, Preschool; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D011446:Prospective Studies; D012042:Registries; D055815:Young Adult
keywords: Anaphylactic; epidemiology; incidence; intensive care unit; prognosis; shock