title: Characterisation of systemic reactions to subcutaneous immunotherapy with airborne allergens and classification according to WAO 2010.
abstract: BACKGROUND
  Systemic reactions (SR) to subcutaneous immunotherapy (SCIT) are rare but potentially severe. The use of different definitions and classifications hampered comparability between studies.
  
  
  OBJECTIVE
  To determine the frequency of SR to SCIT with airborne allergens, and to characterise and classify them according to the WAO 2010 recommendations.
  
  
  METHODS
  Cross-sectional, retrospective study. Data on patients, immunotherapy and SR to SCIT were collected from the SCIT record forms. During the study period, 22,332 SCIT injections were administered (3732 patients).
  
  
  RESULTS
  A total of 26 SR (0.1% of administrations) were recorded in 16 (0.6%) patients (median age 22 years, nine males, all with rhinitis and nine with asthma). Twenty-one (81%) SR occurred during the induction phase; eight (31%) in the first hour after administration. According to the WAO 2010 classification, 12 (46%) were grade 1 and 14 (54%) were grade 2. Most grade 2 reactions occurred in asthmatics, presented as mild asthma symptoms and resolved without need for medical observation. Only two individuals without asthma presented grade 2 reactions, both with concurrent cutaneous and low respiratory symptoms; both required medical observation and treatment despite late onset; 82% (n=12) of grade 2 reactions were late. No grade 3-5 reactions were registered and only one patient needed adrenaline treatment. No risk factors for SR to SCIT were identified in this study.
  
  
  CONCLUSIONS
  SCIT is a safe treatment when administered by trained staff. The WAO 2010 classification might be useful for retrospectively classifying the severity of reactions, although its usefulness in treatment decision needs further research.
authors.affiliation: Centro Hospitalar São João, E.P.E., Serviço de Imunoalergologia, Porto, Portugal. Electronic address: natachalsantos@gmail.com.
authors.forename: N
authors.initials: N
authors.lastname: Santos
authors.affiliation: Centro Hospitalar São João, E.P.E., Serviço de Imunoalergologia, Porto, Portugal.
authors.forename: A M
authors.initials: AM
authors.lastname: Pereira
authors.affiliation: Centro Hospitalar São João, E.P.E., Serviço de Imunoalergologia, Porto, Portugal.
authors.forename: R
authors.initials: R
authors.lastname: Silva
authors.affiliation: Centro Hospitalar São João, E.P.E., Serviço de Imunoalergologia, Porto, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Torres da Costa
authors.affiliation: Centro Hospitalar São João, E.P.E., Serviço de Imunoalergologia, Porto, Portugal.
authors.forename: J L
authors.initials: JL
authors.lastname: Plácido
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology*; D001249:Asthma / Q000150:complications / Q000276:immunology / Q000628:therapy*; D003430:Cross-Sectional Studies; D003888:Desensitization, Immunologic / Q000009:adverse effects*; D064420:Drug-Related Side Effects and Adverse Reactions / Q000145:classification* / Q000209:etiology; D005260:Female; D006801:Humans; D007279:Injections, Subcutaneous; D008297:Male; D052638:Particulate Matter / Q000276:immunology*; D012189:Retrospective Studies; D012220:Rhinitis / Q000150:complications / Q000276:immunology / Q000628:therapy*; D012867:Skin / Q000187:drug effects* / Q000473:pathology; D055815:Young Adult
chemical_list: D000485:Allergens; D052638:Particulate Matter
keywords: Allergen immunotherapy; Classification; Systemic reactions