Prevalence and classification of rhinitis in preschool children in Portugal: a nationwide study.

BACKGROUND Information on rhinitis epidemiology in preschool children is scarce. OBJECTIVES To estimate, in children with 3-5 years of age, current rhinitis prevalence, to describe rhinitis symptoms and associated sociodemographic characteristics, and to report allergic rhinitis and its impact on asthma (ARIA) classification. METHODS Cross-sectional, nationwide, population-based study including children aged 3-5 years. A multistep selection strategy was used to obtain a representative sample. Data were collected at kindergartens and parish centers by face-to-face interview to caregivers, using an adapted ISAAC questionnaire. 'Current rhinitis' (CR) was defined as the presence of ≥1 rhinitis symptom (repeated sneezing and/or itchy nose, blocked nose for >1 h, or runny nose without having a cold/flu) in the last year. Rhinitis lasting ≥4 days/week and ≥4 consecutive weeks was classified as persistent. Moderate-severe disease interfered 'a moderate amount' or 'a lot' in daily activities. RESULTS Five thousand and eighteen children were included. CR prevalence was 43.4% [95% CI (42.0-44.8%); n = 2179] and that of physician-diagnosed rhinitis was 11.7% [95% CI (10.8-12.6%); n = 588]. Of children with CR, 67% reported blocked nose, 48% rhinorrhea, and 46% sneezing/itchy nose. Considering ARIA classification, 30% of the population had mild intermittent, 3% mild persistent, 7% moderate-severe intermittent, and 3% moderate-severe persistent rhinitis. Children with CR had more current wheezing, physician-diagnosed asthma, self-reported food allergy, and family history of allergic disease. These characteristics were also associated with persistent and moderate-severe rhinitis. CONCLUSIONS This is the first nationwide population-based study reporting rhinitis prevalence and ARIA classification in preschool children. In this age-group, rhinitis is frequent and underdiagnosed. About 25% children with rhinitis presented moderate-severe disease.