title: Subcutaneous and sublingual immunotherapy for seasonal allergic rhinitis: a systematic review and indirect comparison.
abstract: BACKGROUND
  Severe allergic rhinitis uncontrolled by pharmacotherapy can adversely affect quality of life. Both subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT) have demonstrated effectiveness in this patient group; however, it remains uncertain which route of administration is more effective.
  
  
  OBJECTIVE
  We sought to update existing systematic reviews on the clinical effectiveness of SCIT and SLIT versus placebo, to undertake a systematic review of head-to-head trials, and to compare the relative effectiveness of SCIT and SLIT in an adjusted indirect comparison.
  
  
  METHODS
  Standard systematic review methods aimed at minimizing bias were used. Double-blind, randomized, placebo-controlled trials of SCIT or SLIT or trials of SCIT versus SLIT were included. Meta-analysis and indirect comparison meta-analysis with meta-regression were performed.
  
  
  RESULTS
  Updated meta-analyses confirmed statistically significant benefits for SCIT and SLIT compared with placebo in adults and, to a lesser extent, in children. Only 1 head-to-head trial met the inclusion criteria; both this and the indirect comparisons did not provide conclusive results in favor of either SCIT or SLIT based on symptom-medication or quality-of-life scores. There was a trend toward favoring SCIT for symptom and medication scores.
  
  
  CONCLUSIONS
  Although there is clear evidence of effectiveness of both SCIT and SLIT, superiority of one mode of administration over the other could not be consistently demonstrated through indirect comparison, and further research is needed to establish the comparative effectiveness of SCIT versus SLIT.
authors.affiliation: Department of Public Health, Epidemiology & Biostatistics, University of Birmingham, Birmingham, United Kingdom. j.dretzke@bham.ac.uk
authors.forename: Janine
authors.initials: J
authors.lastname: Dretzke
authors.forename: Angela
authors.initials: A
authors.lastname: Meadows
authors.forename: Nicola
authors.initials: N
authors.lastname: Novielli
authors.forename: Aarnoud
authors.initials: A
authors.lastname: Huissoon
authors.forename: Anne
authors.initials: A
authors.lastname: Fry-Smith
authors.forename: Catherine
authors.initials: C
authors.lastname: Meads
mesh_terms: D000286:Administration, Sublingual; D000328:Adult; D000485:Allergens / Q000008:administration & dosage; D002648:Child; D003888:Desensitization, Immunologic / Q000009:adverse effects / Q000379:methods*; D004311:Double-Blind Method; D006801:Humans; D007279:Injections, Subcutaneous; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D006255:Rhinitis, Allergic, Seasonal / Q000628:therapy*; D016896:Treatment Outcome
chemical_list: D000485:Allergens