Definitions of outcomes
Allergic rhinitis was diagnosed by a pediatric allergy specialist using the following criteria: (1) Current upper respiratory symptoms (nasal blockage, rhinorrhea, nasal itching and sneezing after allergen exposure); (2) At least one positive SPT to common inhalant allergens. The symptoms were classified as “seasonal” when they were limited to a certain period or a season, and as “perennial“when they occurred throughout the year. Duration of the symptoms was classified according to ARIA guidelines(6) as “Intermittent ” (the symptoms present less than 4 days a week or for less than 4 consecutive weeks) or “Persistent ” (present more than 4 days a week and for more than 4 consecutive weeks). AR was classified as “mild ” when none of the severity items (sleep disturbance, impairment of daily activities, leisure and/or sport, impairment of school or work and presence of troublesome symptoms) was present, and as “moderate/severe ” in patients with one or more of the aforementioned items.
Allergic conjunctivitis: Defined as the presence of current ocular symptoms (tearing, burning, itching and redness in the eyes) and positive SPT.
Physician-diagnosed asthma: Defined as current symptoms (wheeze and cough) and positive bronchodilator responsiveness (improvement of FEV1 by 12% or more following administration of 200 mcg salbutamol), and/or a positive response to a trial of therapy with inhaled or oral corticosteroids(19).
Atopic dermatitis: Current pruritus and a relapsing eczematous rash typically found over flexor surfaces.
Allergic sensitization: SPT mean wheal diameter at least 3 mm greater compared to the negative control.
Parental asthma and parental allergic rhinitis were determined by questionnaire at enrollment.