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Persistent nocturnal cough in childhood: a population based study
T K Ninan1, L Macdonald, G Russell
1University of Aberdeen, Department of Child Health.
Insights
Persistent nocturnal cough (PNC) in children, without other asthma symptoms, is rarely a sign of hidden asthma. Clinical features of children with PNC align more with asymptomatic children than those with polysymptomatic asthma.
Area of Science:
- Pediatric Pulmonology
- Epidemiology
- Allergy
Background:
- Persistent nocturnal cough (PNC) is a common respiratory symptom in children.
- Its role as an independent marker for childhood asthma requires further investigation.
Purpose of the Study:
- To determine if persistent nocturnal cough (PNC) is a valid independent marker for childhood asthma.
- To compare the clinical features of children with isolated PNC to those with polysymptomatic asthma and asymptomatic children.
Main Methods:
- A cross-sectional epidemiological study involving 4003 primary school children.
- Screening questionnaires identified symptomatic and asymptomatic children for diagnostic interviews.
- Stepwise discriminant analysis was used to categorize children based on symptoms.
Main Results:
- Children with isolated PNC showed clinical features more similar to asymptomatic children than to those with polysymptomatic asthma.
- Prevalence of prematurity was highest in the PNC group (19%).
- While eczema and parental asthma history were more common in PNC and polysymptomatic asthma groups compared to asymptomatic, PNC alone was not a strong indicator of asthma.
Conclusions:
- Persistent nocturnal cough (PNC) in children, when isolated and without other typical asthma symptoms like wheezing or chest tightness, is unlikely to be a manifestation of atypical or hidden asthma in most cases.
- PNC's clinical presentation more closely resembles that of the asymptomatic population.
Abstract:
A cross sectional epidemiological study was carried out to investigate the validity of persistent nocturnal cough (PNC) as an independent marker of childhood asthma. A screening questionnaire on respiratory symptoms was applied to 4003 children attending primary schools in Aberdeen, after which 799 symptomatic children and a random selection of 229 asymptomatic children were invited to attend for a diagnostic interview. Six hundred and seven (359 boys and 248 girls) symptomatic children and 135 asymptomatic children (57 boys and 78 girls) were selected from the screening questionnaires. Of 607 children with respiratory symptoms when interviewed, 27 (nine boys and 18 girls) had isolated PNC, and 97 (51 boys and 46 girls) had multiple symptoms (polysymptomatic asthma). The incidence of prematurity was highest in the group with PNC (19%). The prevalence of hay fever in children with PNC (11%) was similar to that of the asymptomatic group (15%) and less than that in the group with polysymptomatic asthma (41%). Eczema was twice as common in the PNC (19%) as in the asymptomatic children (10%) but only half as common in the polysymptomatic asthma group (35%). The prevalence of a parental history of hay fever was similar in all three groups. The prevalence of a parental history of eczema was similar in the PNC (7%) and asymptomatic (7%) groups but higher in the polysymptomatic asthma group (22%). The prevalence of a history of parental asthma was 30% in children with PNC, 13% in the asymptomatic group, and 42% in those with polysymptomatic asthma. The parents of three (11%) children with PNC were aware of a diagnosis of asthma; two of these children (7%) were on inhaled bronchodilator treatment and one (4%) was on a slow release theophylline preparation. Using a stepwise discriminant analysis procedure, in 18 (67%) children with PNC predicted membership was in the asymptomatic group and only nine (33%) children with PNC were grouped into the polysymptomatic asthma category. It is concluded that the clinical features of children with PNC resembled those of the asymptomatic population more closely than those of the polysymptomatic asthmatic population. In this age group PNC, in the absence of wheeze, shortness of breath or tightness in the chest, is likely to be a manifestation of atypical or hidden asthma in only a minority of cases.