title: Allergen immunotherapy for the prevention of allergy: A systematic review and meta-analysis.
abstract: There is a need to establish the effectiveness, cost-effectiveness, and safety of allergen immunotherapy (AIT) for the prevention of allergic disease.
  
  
  
  Two reviewers independently screened nine international biomedical databases. Studies were quantitatively synthesized using random-effects meta-analyses.
  
  
  
  A total of 32 studies satisfied the inclusion criteria. Overall, meta-analysis found no conclusive evidence that AIT reduced the risk of developing a first allergic disease over the short term (RR = 0.30; 95% CI: 0.04-2.09) and no randomized controlled evidence was found in relation to its longer-term effects for this outcome. There was, however, a reduction in the short-term risk of those with allergic rhinitis developing asthma (RR = 0.40; 95% CI: 0.30-0.54), with this finding being robust to a pre-specified sensitivity analysis. We found inconclusive evidence that this benefit was maintained over the longer term: RR = 0.62; 95% CI: 0.31-1.23. There was evidence that the risk of new sensitization was reduced over the short term, but this was not confirmed in the sensitivity analysis: RR = 0.72; 95% CI: 0.24-2.18. There was no clear evidence of any longer-term reduction in the risk of sensitization: RR = 0.47; 95% CI: 0.08-2.77. AIT appeared to have an acceptable side effect profile.
  
  
  
  AIT did not result in a statistically significant reduction in the risk of developing a first allergic disease. There was, however, evidence of a reduced short-term risk of developing asthma in those with allergic rhinitis, but it is unclear whether this benefit was maintained over the longer term. We are unable to comment on the cost-effectiveness of AIT.
authors.affiliation: Department of Public Health, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Maria
authors.initials: M
authors.lastname: Kristiansen
authors.affiliation: Evidence-Based Health Care Ltd, Edinburgh, UK.
authors.forename: Sangeeta
authors.initials: S
authors.lastname: Dhami
authors.affiliation: Institute for Health and Human Development, University of East London, London, UK.
authors.forename: Gopal
authors.initials: G
authors.lastname: Netuveli
authors.affiliation: Hans Christian Andersen Children's Hospital, Odense University Hospital, Odense, Denmark.
authors.forename: Susanne
authors.initials: S
authors.lastname: Halken
authors.affiliation: Department of Mother and Child Health, The Referral Centre for Food Allergy Diagnosis and Treatment Veneto Region, University of Padua, Padua, Italy.
authors.forename: Antonella
authors.identifier: 0000-0002-5026-5862
authors.initials: A
authors.lastname: Muraro
authors.affiliation: The David Hide Asthma and Allergy Research Centre, St Mary's Hospital, Newport, Isle of Wight, UK.|NIHR Respiratory Biomedical Research Unit, University Hospital Southampton NHS Foundation Trust, Southampton, UK.|Faculty of Medicine, University of Southampton, Southampton, UK.
authors.forename: Graham
authors.initials: G
authors.lastname: Roberts
authors.affiliation: Hospital Medica Sur, Mexico City, Mexico.
authors.forename: Desiree
authors.initials: D
authors.lastname: Larenas-Linnemann
authors.affiliation: Section of Allergy and Clinical Immunology, National Heart and Lung Institute, Imperial College London, Royal Brompton Hospital, London, UK.
authors.forename: Moises A
authors.initials: MA
authors.lastname: Calderón
authors.affiliation: Section of Allergy and Clinical Immunology, National Heart and Lung Institute, Imperial College London, Royal Brompton Hospital, London, UK.
authors.forename: Martin
authors.initials: M
authors.lastname: Penagos
authors.affiliation: Division of Asthma, Allergy and Lung Biology, Department of Paediatric Allergy, MRC & Asthma Centre in Allergic Mechanisms of Asthma, King's College London, London, UK.|St Thomas NHS Foundation trust, London, United Kingdom.
authors.forename: George
authors.initials: G
authors.lastname: Du Toit
authors.affiliation: Department of Allergy & Immunology, Hospital Quironsalud Bizkaia, Bilbao, Spain.
authors.forename: Ignacio J
authors.initials: IJ
authors.lastname: Ansotegui
authors.affiliation: Allergy & Asthma Center Westend, Berlin, Germany.
authors.forename: Jörg
authors.initials: J
authors.lastname: Kleine-Tebbe
authors.affiliation: Clinic for Pediatric Pneumonology and Immunology, Charité Medical University Berlin, Berlin, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Lau
authors.affiliation: Department for Ped Pneumology and Immunology, Charite, Berlin, Germany.
authors.forename: Paolo Maria
authors.initials: PM
authors.lastname: Matricardi
authors.affiliation: Department of Pediatrics, University of Messina, Messina, Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Pajno
authors.affiliation: Institute of Human Development, University of Manchester, Manchester, UK.|Allergy Department, 2nd Pediatric Clinic, University of Athens, Athens, Greece.
authors.forename: Nikolaos G
authors.initials: NG
authors.lastname: Papadopoulos
authors.affiliation: Department of Otorhinolaryngology, Head and Neck Surgery, Medical Faculty Mannheim, Universitätsmedizin Mannheim, Heidelberg University, Mannheim, Germany.|Center for Rhinology and Allergology, Wiesbaden, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Pfaar
authors.affiliation: University of Edinburgh, Edinburgh, UK.
authors.forename: Dermot
authors.initials: D
authors.lastname: Ryan
authors.affiliation: Section of Allergy and Clinical Immunology, National Heart and Lung Institute, Imperial College London, Royal Brompton Hospital, London, UK.
authors.forename: Alexandra F
authors.initials: AF
authors.lastname: Santos
authors.affiliation: Netherlands Anaphylaxis Networks, The Netherlands.
authors.forename: Frans
authors.initials: F
authors.lastname: Timmermanns
authors.affiliation: Department for Ped Pneumology and Immunology, Charite, Berlin, Germany.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Wahn
authors.affiliation: University of Edinburgh, Edinburgh, UK.
authors.forename: Aziz
authors.initials: A
authors.lastname: Sheikh
mesh_terms: D000818:Animals; D001249:Asthma / Q000517:prevention & control*; D003362:Cost-Benefit Analysis; D003888:Desensitization, Immunologic / Q000379:methods*; D006801:Humans; D006967:Hypersensitivity / Q000276:immunology / Q000628:therapy*; D012220:Rhinitis; D012306:Risk
keywords: allergen immunotherapy; allergic diseases; allergy; atopy; prevention; sensitization