Relationship between rhinitis and nocturnal cough in school children

Background: There is a complex relationship between rhinitis, asthma, and nocturnal cough. Methods: To evaluate whether rhinitis is an important risk factor for nocturnal cough and whether this effect is independent of asthma, we analyzed data collected using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire in a population-based nationwide survey. A child who had experienced a dry cough at night in the past 12months in the absence of a cold was defined as having nocturnal cough. Results: After excluding 11,475 records with incomplete data, data from 136,506 children were analyzed. Nocturnal cough was significantly more prevalent in children with current rhinitis compared with children without rhinitis. The association between rhinitis and nocturnal cough was significant in children who had current asthma (adjusted OR [95% CI]: 2.26 [2.00-2.56] in children aged 6-7yr, 1.90 [1.58-2.30] in those aged 13-14yr, and 1.86 [1.60-2.19] in those aged 16-17yr), and this association was even higher among children who had no asthma (adjusted OR [95% CI]: 3.65 [3.36-3.97] in children aged 6-7yr, 3.05 [2.79-3.32] in those aged 13-14yr, and 2.69 [2.51-2.88] in those aged 16-17yr). Conclusions: There was a close association between rhinitis and nocturnal cough in young children through adolescents, and this effect was independent of asthma. Upper airways should be examined in children with nocturnal cough.