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Recurrent cough in childhood and its relation to asthma
A L Wright1, C J Holberg, W J Morgan
1Department of Pediatrics and Respiratory Sciences Center, College of Medicine, University of Arizona, Tucson, USA.
Insights
Recurrent cough (RC) in children without wheeze is distinct from asthma. RC with wheeze shares risk factors with asthma, indicating different underlying causes and potential for varied treatment approaches.
Area of Science:
- Pediatric Respiratory Medicine
- Allergy and Immunology
- Epidemiology
Background:
- Recurrent cough (RC) in children is a common concern, often evaluated in relation to asthma.
- Distinguishing between RC with and without wheezing is crucial for understanding underlying pathophysiology.
Purpose of the Study:
- To investigate risk factors for childhood recurrent cough (RC).
- To examine the relationship between RC and asthma.
- To differentiate between RC with and without wheeze.
Main Methods:
- Prospective, longitudinal study of 987 children at age 6.
- Assessment of RC via questionnaire, defining it as >= 2 episodes of cough without a cold in the past year.
- Evaluation of serum IgE, skin prick tests, lung function (V'maxFRC), and response to cold air challenge.
Main Results:
- Children with RC and wheeze showed increased respiratory illness, atopy, lower V'maxFRC, and greater lung function decline compared to controls.
- Parental smoking was a risk for RC without wheeze.
- Male gender, maternal allergy, early wheezing lower respiratory tract illness (LRI), and high IgE were risks for RC with wheeze.
- RC often resolved by age 6 or 11.
- High IgE and positive skin prick tests predicted persistent RC to age 6 in wheezing children.
Conclusions:
- Recurrent cough without wheeze appears distinct from classic asthma.
- RC with wheeze shares risk factors with asthma, suggesting overlapping but distinct conditions.
- Labeling distinct syndromes under a single term like "recurrent cough" may obscure underlying pathophysiological differences.
Abstract:
Risk factors for recurrent cough (RC) in childhood, and its relation to asthma were investigated as part of the prospective, longitudinal Tucson Children's Respiratory Study. RC, defined as > or = 2 episodes of cough without a cold in the past year, was assessed by questionnaire in 987 children at age 6. Children having RC without wheeze (n = 154) did not differ from children with neither symptom (n = 610) in serum IgE levels, skin test response, size-corrected forced expiratory flow, or percentage of decline following cold air challenge. In contrast, children with both RC and wheeze (n = 116) had significantly more respiratory illness, more atopy, lower flow at end-tidal expiration (V'maxFRC), and greater declines in lung function following cold air challenge than children with neither symptom. Current parental smoking was a risk for RC without wheeze, whereas male gender, maternal allergy, wheezing lower respiratory tract illness (LRI) in early life, and high IgE were significant risks for RC with wheeze, compared with children having neither symptom. RC early in life resolved in the majority of children, between ages 2-3 yr and age 6, and between age 6 and age 11. High IgE and positive skin prick test were associated with persistence of RC to age 6 among children who wheezed, and markers of allergy were associated with persistence of RC between 6 and 11 yr. These findings suggest that recurrent cough in the absence of wheeze differs in important respects from classic asthma, and using the same label to refer to these distinct syndromes may obscure their diverse pathophysiologies.