title: A prospective, clinical study on asymptomatic sensitisation and development of allergic rhinitis: high negative predictive value of allergological testing.
abstract: BACKGROUND
  Asymptomatic aeroallergen sensitisation affects approximately 10% of Western adolescents and is an established risk factor for the development of respiratory allergy. The reported incidence is 2-20% annually. Previous studies are based on out-seasonal symptom recollection or selected populations, conferring bias towards higher incidence rates.
  
  
  OBJECTIVE
  The aim was to determine the incidence of onset of symptoms among clinically well-characterised asymptomatic, sensitised subjects compared with controls, and to evaluate the predictive values of common allergological tests.
  
  
  METHODS
  We performed a prospective, clinical, non-interventional, 2-year follow-up study on subjects (identified by population screening) with seasonal allergic birch or grass pollen rhinitis (n = 52), asymptomatic sensitisation to grass or birch (AS, n = 52) or non-atopic, healthy control subjects (n = 39). Experimental allergen susceptibility was assessed at inclusion and at follow-up by skin prick test, conjunctival challenge, intradermal late-phase reaction and measurement of specific IgE. Participants completed in-seasonal symptom and medication diaries during 2 subsequent seasons.
  
  
  RESULTS
  We observed an annual incidence rate of 5% for the onset of symptoms in the AS group (healthy control group 0%). At baseline, the AS group displayed intermediate experimental allergen susceptibility. Subjects developing symptoms had higher levels of specific IgE and larger late-phase reaction than those persistently asymptomatic. However, the positive predictive values were low (14-27%) in contrast to the negative predictive values (95-100%).
  
  
  CONCLUSIONS
  In a well-characterised young population, asymptomatic aeroallergen sensitisation conferred a low risk for onset of symptoms during the 2-year follow-up. Persistent asymptomatic phenotype could be accurately predicted by negative results from simple allergological testing.
authors.affiliation: Allergy Clinic, Copenhagen University Hospital, Gentofte, Denmark. uffe.bodtger@dadlnet.dk
authors.forename: Uffe
authors.initials: U
authors.lastname: Bodtger
authors.forename: Kristian
authors.initials: K
authors.lastname: Assing
authors.forename: Lars K
authors.initials: LK
authors.lastname: Poulsen
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology; D029662:Betula / Q000276:immunology; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D015994:Incidence; D008297:Male; D008875:Middle Aged; D006109:Poaceae / Q000276:immunology; D011058:Pollen / Q000276:immunology; D011237:Predictive Value of Tests; D011446:Prospective Studies; D006255:Rhinitis, Allergic, Seasonal / Q000175:diagnosis* / Q000453:epidemiology* / Q000276:immunology; D012680:Sensitivity and Specificity; D012882:Skin Tests; D055815:Young Adult
chemical_list: D000485:Allergens; D007073:Immunoglobulin E