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Clinical patterns and natural history of asthma
1Pediatric Allergy and Pulmonary Division, University of Iowa, Iowa City 52242, USA. weinberger@uiowa.edu
Insights
Childhood asthma often starts with RSV infections. Most children improve, but some develop persistent asthma, especially those with symptoms unrelated to viral respiratory infections.
Area of Science:
- Pediatric Pulmonology
- Epidemiology of Asthma
- Viral Respiratory Infections
Background:
- Childhood asthma frequently originates in infancy, often linked to respiratory syncytial virus (RSV) infections.
- While most infants contract RSV, only a subset develops lower respiratory illness, with 25-50% experiencing recurrent asthma from viral respiratory infections (VRI).
- Young children under 5 exhibit high VRI frequency and the highest asthma hospitalization rates.
Purpose of the Study:
- To investigate the long-term natural history of childhood asthma.
- To identify predictors of persistent or adult-onset asthma.
- To assess the impact of asthma on lung function over time.
Main Methods:
- A 35-year longitudinal study tracking the natural history of asthma in children.
- Observation of asthma development, triggers (VRI, exercise), and progression.
- Monitoring of lung function, specifically forced expiratory volume at one second (FEV1).
Main Results:
- Approximately 20% of 7-year-olds had asthma, primarily episodic and linked to VRI.
- The majority of childhood asthma cases improved with age.
- A significant minority experienced recurrent adult asthma, particularly those with non-VRI-related childhood symptoms. Persistent asthma was rare.
- Lung function (FEV1) remained normal in episodic asthma but was low in severe, persistent cases, irrespective of treatment quality.
Conclusions:
- Childhood asthma's trajectory varies, with VRI-triggered episodic illness often resolving.
- Asthma symptoms independent of VRI in childhood are stronger predictors of persistent or adult-onset asthma.
- Lung function decline is associated with severe, persistent asthma, highlighting the importance of early identification and management.
Abstract:
Childhood asthma typically begins in infancy with a respiratory syncytial virus (RSV) infection. Although the majority of infants become infected with RSV, lower respiratory illness develops in only about 20%. About 25% to 50% of those subsequently experience recurrent acute asthma from viral respiratory infections (VRI). Children younger than 5 years have a high frequency of VRI and have the highest frequency of hospitalization for asthma of any age group. In a 35-year study of the natural history of asthma, 20% of 7-year-old children were found to have asthma, but most had only episodic illness with VRI. The majority of those children improved with age, but a substantial minority continued to have recurrent episodes as adults, generally induced by VRI or exercise. Persistent asthma developed in only a few. Children who had symptoms of asthma without VRI were more likely to continue having frequent episodic or chronic asthma as adults. Despite generally suboptimal treatment during the 35 years of the study, forced expiratory volume at one second did not deteriorate over time; it remained normal in children who had only episodic asthma, and it was consistently low in the children with severe, persistent asthma.