title: Analysis of allergen immunotherapy studies shows increased clinical efficacy in highly symptomatic patients.
abstract: BACKGROUND
  The assessment of allergen immunotherapy (AIT) efficacy in the treatment for seasonal allergic rhinoconjunctivitis (SAR) symptoms is challenging. Allergen immunotherapy differs from symptomatic therapy in that while symptomatic therapy treats patients after symptoms appear and aims to reduce symptoms, AIT is administered before symptoms are present and aims to prevent them. Thus, clinical studies of AIT can neither establish baseline symptom levels nor limit the enrolment of patients to those with the most severe symptoms. Allergen immunotherapy treatment effects are therefore diluted by patients with low symptoms for a particular pollen season. The objective of this analysis was to assess the effect possible to achieve with AIT in the groups of patients presenting the most severe allergic symptoms.
  
  
  METHODS
  Study centres were grouped into tertiles categorized according to symptom severity scores observed in the placebo patients in each centre (low, middle and high tertiles). The difference observed in the average score in each tertile in active vs placebo-treated patients was assessed. This allowed an estimation of the efficacy that could be achieved in patients from sites where symptoms were high during the pollen season.
  
  
  RESULTS
  An increased treatment effect was observed in the most severe patients and was independent of the study analysed and symptom score used.
  
  
  CONCLUSIONS
  The use of a tertile approach to analyse efficacy in AIT in SAR clinical studies can give a more accurate assessment of potential clinical benefit.
authors.affiliation: Infection, Inflammation & Immunity Research Division, School of Medicine, Southampton General Hospital, UK.
authors.forename: P
authors.initials: P
authors.lastname: Howarth
authors.forename: H-J
authors.initials: HJ
authors.lastname: Malling
authors.forename: M
authors.initials: M
authors.lastname: Molimard
authors.forename: P
authors.initials: P
authors.lastname: Devillier
mesh_terms: D000286:Administration, Sublingual; D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology; D002648:Child; D002675:Child, Preschool; D003233:Conjunctivitis, Allergic / Q000209:etiology / Q000276:immunology / Q000503:physiopathology / Q000628:therapy*; D003888:Desensitization, Immunologic / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D006109:Poaceae / Q000009:adverse effects / Q000276:immunology*; D011058:Pollen / Q000009:adverse effects / Q000276:immunology; D016032:Randomized Controlled Trials as Topic; D006255:Rhinitis, Allergic, Seasonal / Q000209:etiology / Q000276:immunology / Q000503:physiopathology / Q000628:therapy*; D012621:Seasons; D012720:Severity of Illness Index; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000485:Allergens