Age-related changes in childhood wheezing characteristics: A whole population study.

BACKGROUND: Wheezing illnesses are characterized by phenotypic variability, which changes with age, but few studies report on a wide age range of children. We studied how prevalence, severity, and triggers of wheeze vary throughout childhood.

METHODS: We analyzed data from a large population-based cohort of children from Leicestershire, UK, who were followed from infancy through late adolescence using postal questionnaires. We used generalized estimating equations to describe age-related changes in prevalence of any wheeze: episodic viral and multiple trigger wheeze; wheeze triggered by exercise, aeroallergens, food/drinks, laughing/crying; and of severe wheeze (frequent attacks, shortness of breath, sleep disturbance, disturbance of daily activities) from age 1-18 years. We analyzed this in the entire cohort (absolute prevalence) and separately among children with wheeze (relative prevalence).

RESULTS: This study included 7670 children. Current wheeze was most common in 1-year-olds (36%) and then decreased in prevalence to reach 17% in children aged 14-17 years. Absolute prevalence of episodic viral wheeze (EVW) decreased with age (from 24% to 7%), while multiple trigger wheeze (MTW) remained relatively constant throughout childhood (8-12%). Among children with wheeze, the proportion with EVW decreased, and the proportion with MTW increased with age. In older children, wheeze triggered by exercise or aeroallergens, and wheeze accompanied by shortness of breath became more frequent, while wheeze triggered by food or laughter, and sleep disturbance decreased in prevalence.

CONCLUSION: Knowledge of these age-related changes in wheezing illness is informative for health care planning and the design of future research projects and questionnaires.