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Childhood cough variant asthma and its relationship to classic asthma
Makoto Todokoro1, Hiroyuki Mochizuki, Kenichi Tokuyama
1Department of Pediatrics, Gunma University School of Medicine, Maebashi, Japan. mochihi@med.gunma-u.ac.jp
Insights
In children with chronic cough, cough variant asthma (CVA) is common. Early onset of CVA, not bronchial hyperresponsiveness, predicts the development of classic asthma in childhood.
Area of Science:
- Pediatric Pulmonology
- Asthma Research
- Respiratory Medicine
Background:
- Chronic cough in children can be diagnosed as cough variant asthma (CVA) when no other cause is found.
- The long-term outlook for infants and children diagnosed with CVA remains uncertain.
Purpose of the Study:
- To investigate the link between cough variant asthma (CVA) and the development of classic asthma in childhood.
- To identify risk factors for the progression from CVA to classic asthma.
Main Methods:
- A methacholine inhalation challenge using transcutaneous oxygen pressure (tcPO2) monitoring diagnosed CVA in 75 children with chronic cough.
- Patients with CVA were followed for over 3 years to track the onset of classic asthma.
- Comparison groups included children with classic asthma and age-matched controls.
Main Results:
- Over 3 years, 54% of children diagnosed with CVA developed classic asthma.
- A significant difference in the age of CVA onset was observed between children who developed classic asthma and those who did not.
- No significant difference in methacholine sensitivity (Dmin-PO2) was found between these groups.
Conclusions:
- Cough variant asthma (CVA) was diagnosed in 75% of children presenting with chronic cough.
- The age at onset of CVA, rather than the severity of bronchial hyperresponsiveness, is a key risk factor for developing classic asthma.
- Early detection and monitoring of CVA, particularly in younger children, are crucial for predicting asthma development.
Background:
In pediatrics, some patients with chronic cough who have no evidence of a causative disease are diagnosed as having cough variant asthma (CVA). The precise prognosis of infants and children with CVA, however, is still unclear.
Objective:
To evaluate the relationship between CVA and classic asthma in childhood.
Methods:
To diagnose CVA, we performed a methacholine inhalation challenge with use of a transcutaneous oxygen pressure (tcPO2) monitoring system in 100 children with chronic cough, and 75 children (45 boys and 30 girls; mean age, 5.7 years) were diagnosed as having CVA. These patients underwent follow-up monitoring for more than 3 years to ascertain whether classic asthma developed. For comparison, 53 age-matched children with classic asthma (30 boys and 23 girls; mean age, 5.6 years) and 30 age-matched control subjects (12 boys and 18 girls; mean age, 5.5 years) also participated in this study. Consecutive doses of methacholine were doubled until a 10% decrease in tcPO2 from the baseline was reached. The cumulative dose of methacholine at the inflection point of tcPO2 (Dmin-PO2) was considered to represent the sensitivity of tcPO2 to inhaled methacholine.
Results:
After 3 years or more of follow-up assessments, 52 of the 75 patients answered our questionnaire. Of the responding patients, 28 had been diagnosed as having classic asthma. A significant difference was noted in the age at onset of CVA between the children in whom classic asthma developed (the asthma-developed group) and those in whom classic asthma did not develop (the asthma-free group). No statistically significant differences in Dmin-PO2 between the asthma-developed group and the asthma-free group or between the girls and the boys, however, were foun
Conclusions:
This study showed that 75% of children with chronic cough had CVA, that classic asthma developed in 54% of the children with CVA, and that it is not the severity of bronchial hyperresponsiveness in CVA but the age at onset of CVA that is a risk factor for the development of classic asthma in childhood CVA.