title: Risk factors for severe anaphylaxis in patients receiving anaphylaxis treatment in US emergency departments and hospitals.
abstract: BACKGROUND
  Although reported risk factors for severe anaphylaxis include older age, presence of comorbid medical conditions, and concomitant medications, previous studies have used varying definitions for anaphylaxis and heterogeneous methodology.
  
  
  OBJECTIVE
  To describe risk factors for severe anaphylaxis among US patients treated in emergency departments (EDs) or hospitals for anaphylaxis.
  
  
  METHODS
  Individuals with an ED visit/hospitalization for anaphylaxis were identified from 2 MarketScan Research Databases using an expanded International Classification of Diseases, Ninth Revision, Clinical Modification diagnosis code algorithm. Eligibility for the current study required continuous medical and prescription coverage for at least 1 year before and after the index date. Severe anaphylaxis was defined as a reaction requiring hospital admission.
  
  
  RESULTS
  Among 11,972 individuals, 2,622 (22%) had severe anaphylaxis. Unadjusted analysis showed that severe anaphylaxis was associated with older age and higher comorbidity burden. These patients were also less likely to have filled an epinephrine autoinjector (EAI) prescription or visited an allergist/immunologist, but more likely to have had an ED visit/hospitalization (any cause). On multivariable analysis, filling an EAI prescription (odds ratio [OR], 0.64; 95% CI, 0.53-0.78) or visiting an allergist/immunologist (OR, 0.78; 95% CI, 0.63-0.95) before the index event was associated with a lower risk of severe anaphylaxis, while any previous ED visit (OR, 1.18; 95% CI, 1.07-1.30) or hospitalization (OR, 1.55; 95% CI, 1.36-1.75) was associated with a higher risk of severe anaphylaxis.
  
  
  CONCLUSIONS
  In this large cohort with an ED visit or hospitalization for anaphylaxis, 22% had severe anaphylaxis. Pre-index preventive anaphylaxis care (ie, EAI prescription fill and allergist/immunologist visit) was associated with a significantly lower risk, supporting the benefits of preventive anaphylaxis care in real-world practice.
authors.affiliation: Department of Emergency Medicine, Weill Cornell Medical College, New York, NY. Electronic address: sunday.clark@gmail.com.
authors.forename: Sunday
authors.initials: S
authors.lastname: Clark
authors.affiliation: Sanofi US, Bridgewater, NJ.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Wei
authors.affiliation: Department of Pediatrics, Rhode Island Hospital, Alpert School of Medicine at Brown University, Providence, RI.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Rudders
authors.affiliation: Department of Rheumatology, Allergy, and Immunology, the Department of Medicine, and the Department of Emergency Medicine, Massachusetts General Hospital, Harvard Medical School, Boston, Mass.
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D000328:Adult; D000367:Age Factors; D000707:Anaphylaxis / Q000453:epidemiology* / Q000517:prevention & control*; D001993:Bronchodilator Agents / Q000008:administration & dosage*; D016208:Databases, Factual; D004632:Emergency Medical Services; D004636:Emergency Service, Hospital; D004837:Epinephrine / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012307:Risk Factors; D012646:Self Administration; D012720:Severity of Illness Index; D014481:United States / Q000453:epidemiology
chemical_list: D001993:Bronchodilator Agents; D004837:Epinephrine
keywords: Anaphylaxis; emergency department; hospitalization; severity