Rhinitis in children: co-morbidities and phenotypes.

Rhinitis and its co-morbidities affect quality of life; and in children, little is known. We therefore aimed to describe the co-morbidities and phenotypes of current rhinitis in 10-yr-old Norwegian children. We used information on rhinitis, asthma, allergic sensitization, anaphylaxis, and lung function tests from clinical examinations and structured parental interviews of 1019 children included in the birth cohort study, the Environment and Childhood Asthma Study, in Oslo. Current rhinitis was reported in 254 (25.0%) of the children, and 87.4% had at least one allergy-related co-morbidity of rhinitis, with conjunctivitis the most prevalent (75.6%). Overall, 11.8% of the children had conjunctivitis combined with current asthma and atopic eczema. Children with rhinitis were also more likely to have severe bronchial hyperresponsiveness (BHR) (PD(20) <or= 1 micromol methacholine) than children without rhinitis (17.5% and 5.8%, respectively, p < 0.001), as well as BHR (PD(20) <or= 8 micromol). The children with rhinitis and allergic sensitization (72.8%) had more frequently BHR, severe BHR, and conjunctivitis, but did not differ with respect to any other co-morbidity from children with rhinitis without allergic sensitization. Children with symptoms reported by exposure to both pollen and furry pets had more often asthma, wheeze, and BHR compared to the children who reported rhinitis symptoms only when exposed to pollen (91.9% of these had symptoms in spring/summer only). In conclusion, current rhinitis is closely associated with conjunctivitis, asthma, atopic eczema, and BHR in childhood. Conjunctivitis and BHR were most strongly linked to rhinitis with allergic sensitization.