title: The current overuse and misuse of meta-analyses on sublingual immunotherapy: the case of grass pollen allergy.
abstract: OBJECTIVE
  Meta-analysis provides the highest level of evidence-based efficacy of a medical treatment or intervention. Allergen immunotherapy in its two forms of subcutaneous immunotherapy and sublingual immunotherapy (SLIT) is an effective treatment of respiratory allergy as shown by meta-analyses, but in recent years there has been an overflow of meta-analyses on SLIT, with contrasting results that may generate confusion among physicians.
  
  
  RESULTS
  It can be observed that flaws are often present in meta-analyses including: incorrect selection of trials, inappropriate use of evaluation parameters for the analysis, and unsuitable analyses. For instance, it is clear that a meta-analysis of several small studies does not predict the results of a single large study that remains the gold standard to assess the efficacy and safety of a treatment. To assess the interest of the matter, we calculated the number of citations of meta-analyses on SLIT efficacy in the 10 years after the first publication in 2005 and detected a continuous decrease in citations.
  
  
  CONCLUSIONS
  Today, the appropriateness of a meta-analysis should be carefully evaluated, taking into account that a meta-analysis uses a statistical approach to combine the results from multiple small studies to increase power, to improve estimates of the size of the effect, and/or to resolve uncertainty when reports disagree. Editors and reviewers of medical journals should consider that to judge a meta-analysis requires a high level of expertise that is obvious in reviewers belonging to the Cochrane organization.
authors.affiliation: aDepartment of Clinical & Experimental Medicine, University of Parma, Parma bASST Centro Specialistico G. Pini /CTO, Milan cAllergy and Respiratory Diseases, IRCCS San Martino-IST-University of Genoa, Genoa, Italy.
authors.forename: Erminia
authors.initials: E
authors.lastname: Ridolo
authors.forename: Cristoforo
authors.initials: C
authors.lastname: Incorvaia
authors.forename: Bruna Luciana
authors.initials: BL
authors.lastname: Gritti
authors.forename: Giovanni
authors.initials: G
authors.lastname: Passalacqua
mesh_terms: D000485:Allergens / Q000276:immunology; D000818:Animals; D052179:Antigens, Plant / Q000276:immunology; D019317:Evidence-Based Medicine; D006801:Humans; D017712:Peer Review, Research; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology / Q000628:therapy*; D063729:Sublingual Immunotherapy / Q000379:methods*
chemical_list: D000485:Allergens; D052179:Antigens, Plant