Dysfunctional breathing in children with asthma: a rare but relevant comorbidity.

Hyperventilation and other clinical manifestations of dysfunctional breathing have been reported in childhood, but the prevalence is unknown. In adults, dysfunctional breathing may be a relevant comorbidity in asthma. We aimed to determine the prevalence of dysfunctional breathing in children with asthma and its impact on asthma control. We performed a cross-sectional survey in 203 asthmatic children (aged 5-18 years), using the Nijmegen Questionnaire and the paediatric Asthma Control Questionnaire. Dysfunctional breathing was found in 11 (5.3%) children; more females (eight (12.9%) out of 62) than males (three (2.1%) out 144, p=0.002). There was a dose-dependent relationship between increasing Nijmegen Questionnaire scores (increased risk of dysfunctional breathing) and poorer asthma control. Poor asthma control was more common in patients with dysfunctional breathing (10 (90.9%) out of 11 children) than in children without (65 (32.3%) out of 192 children; OR 19.3, 95% CI 3.14-430.70; p<0.0001). The median Asthma Control Questionnaire in children with dysfunctional breathing was higher (median (range) 2.00 (1.50-3.17)) than in children without (0.50 (0.17-1.17); p<0.001). The prevalence of dysfunctional breathing in children and adolescents referred to a hospital-based paediatric asthma clinic for severe or difficult-to-control asthma is 5%. The association between dysfunctional breathing and asthma control suggests that this may be a clinically relevant comorbidity in paediatric asthma.