title: Efficacy of allergen immunotherapy in reducing the likelihood of developing new allergen sensitizations: a systematic review.
abstract: BACKGROUND
  Guidelines and position papers indicate that allergen immunotherapy (AIT) is the only disease-modifying treatment, including prevention of the onset of new allergen sensitizations. However, this preventive effect was shown by only a few observational studies. Our aim was to systematically review the efficacy of AIT in preventing the onset of new allergen sensitizations.
  
  
  METHODS
  Computerized bibliographic searches of Medline, EMBASE, and the Cochrane Library (through June 2015) were supplemented with manual searches of reference lists. Observational studies or randomized controlled trials with a long-term observation period were included. Paired reviewers extracted data about study characteristics and assessed biases. The end point was the risk difference in the onset of new allergen sensitizations between patients treated with AIT and pharmacotherapy. The strength of the evidence was graded based on the risk of bias, consistency, and magnitude of effect, according to the GRADE Working Group's guide.
  
  
  RESULTS
  Eighteen studies (1049 children, 10 057 adults) met the inclusion criteria. The risk of bias was high in all but one study. Low evidence supports the position that AIT prevents the onset of new allergen sensitizations, with 10 of 18 studies reporting a reduction in the onset of new sensitizations in patients treated with AIT vs placebo. Small studies and studies with a shorter follow-up showed the highest benefit of AIT.
  
  
  CONCLUSIONS
  The overall evidence provides a low-grade level of the evidence supporting the efficacy of AIT in preventing the onset of new allergen sensitizations, but high-quality studies could change this estimate.
authors.affiliation: Scuola e Cattedra di Allergologia e Immunologia Clinica, Dipartimento dell'Emergenza e dei Trapianti d'Organo (D.E.T.O.), Università di Bari 'Aldo Moro', Bari, Italy.
authors.forename: D
authors.initials: D
authors.lastname: Di Bona
authors.affiliation: Dipartimento di Scienze Economiche Aziendali e Statistiche, Università degli Studi di Palermo, Palermo, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Plaia
authors.affiliation: Dipartimento BioMedico di Medicina Interna e Specialistica (Di.Bi.M.I.S), Università degli Studi di Palermo, Palermo, Italy.
authors.forename: M S
authors.initials: MS
authors.lastname: Leto-Barone
authors.affiliation: Dipartimento BioMedico di Medicina Interna e Specialistica (Di.Bi.M.I.S), Università degli Studi di Palermo, Palermo, Italy.
authors.forename: S
authors.initials: S
authors.lastname: La Piana
authors.affiliation: Scuola e Cattedra di Allergologia e Immunologia Clinica, Dipartimento dell'Emergenza e dei Trapianti d'Organo (D.E.T.O.), Università di Bari 'Aldo Moro', Bari, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Macchia
authors.affiliation: Dipartimento BioMedico di Medicina Interna e Specialistica (Di.Bi.M.I.S), Università degli Studi di Palermo, Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Di Lorenzo
mesh_terms: D000485:Allergens / Q000008:administration & dosage / Q000276:immunology*; D000818:Animals; D003888:Desensitization, Immunologic / Q000009:adverse effects / Q000379:methods; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000276:immunology* / Q000517:prevention & control / Q000628:therapy*; D007114:Immunization; D007073:Immunoglobulin E / Q000276:immunology; D016017:Odds Ratio; D016896:Treatment Outcome
chemical_list: D000485:Allergens; D007073:Immunoglobulin E
keywords: GRADE; allergen immunotherapy; asthma; rhinoconjunctivitis; systematic review