title: Network meta-analysis shows commercialized subcutaneous and sublingual grass products have comparable efficacy.
abstract: BACKGROUND
  Subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) have been shown to effectively treat grass pollen allergies, although direct comparisons are sparse.
  
  
  OBJECTIVE
  To estimate the relative efficacy of SLIT tablets compared with SCIT and SLIT drops in commercially available products though network meta-analysis.
  
  
  METHODS
  A literature search of MEDLINE, Embase, and Cochrane Library publications. Randomized, double-blind clinical trials of SCIT, SLIT drops, and SLIT tablets for grass pollen were included. Bayesian network meta-analyses estimated the standardized mean difference (SMD) across 3 immunotherapy modalities on allergic rhinoconjunctivitis symptom and medication score data from publications or received from authors. Both fixed and random effects models were investigated.
  
  
  RESULTS
  Thirty-seven studies were included in meta-analyses for symptom scores and 31 studies for medication scores. In the random effects model, SCIT and SLIT tablets were significantly different from placebo for symptom scores: SMDs (95% CI) of -0.32 (-0.45 to -0.18) and -0.32 (-0.41 to -0.23), respectively. No significant difference was identified for SLIT drops compared with placebo (SMD, -0.17; -0.37 to 0.04). For medication scores, significant differences compared with placebo were observed for SCIT (SMD, -0.33; 95% CI, -0.52 to -0.13), SLIT tablets (SMD, -0.23; 95% CI, -0.29 to -0.17), and SLIT drops (SMD, -0.44; 95% CI, -0.83 to -0.06). Network meta-analysis revealed no significant differences in SMDs (95% credible interval) for symptom scores (0.0145 [-0.19 to 0.23]) or medication scores (0.133 [-0.31 to 0.57]) between SLIT tablets and SCIT, or for symptom scores (-0.175 [-0.37 to 0.02]) and medication scores (0.188 [-0.18 to 0.56]) between SLIT tablets and SLIT drops.
  
  
  CONCLUSIONS
  The comparisons for grass pollen immunotherapy products commercialized in at least 1 country indicate comparable reductions in allergic rhinoconjunctivitis symptoms and supplemental medication use for SLIT tablets and SCIT in the first pollen season.
authors.affiliation: National Jewish Health, Denver, Colo. Electronic address: nelsonh@njhealth.org.
authors.forename: Harold
authors.initials: H
authors.lastname: Nelson
authors.affiliation: Optum Burlington, ON, Canada.
authors.forename: Shannon
authors.initials: S
authors.lastname: Cartier
authors.affiliation: Merck & Co, Inc, Whitehouse Station, NJ.
authors.forename: Felicia
authors.initials: F
authors.lastname: Allen-Ramey
authors.affiliation: ALK Hørsholm, Denmark.
authors.forename: Simon
authors.initials: S
authors.lastname: Lawton
authors.affiliation: Imperial College London, Section of Allergy and Clinical Immunology, National Heart and Lung Institute, Royal Hospital Brompton, London, United Kingdom.
authors.forename: Moises A
authors.initials: MA
authors.lastname: Calderon
mesh_terms: D000286:Administration, Sublingual; D003233:Conjunctivitis, Allergic / Q000628:therapy*; D003888:Desensitization, Immunologic / Q000379:methods*; D006801:Humans; D007279:Injections, Subcutaneous; D006109:Poaceae / Q000276:immunology*; D016032:Randomized Controlled Trials as Topic; D006255:Rhinitis, Allergic, Seasonal / Q000628:therapy*; D016896:Treatment Outcome
keywords: Allergen immunotherapy; grass pollen; immunotherapy; meta-analysis; subcutaneous immunotherapy; sublingual immunotherapy