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[Characteristics of airway hyperresponsiveness in children with chronic cough of different causes]
Xingmei Yu1, Haiyan Zhu, Chuangli Hao2
1Department of Respiratory Diseases, Children's Hospital of Soochow University, Suzhou 215003, China.
Insights
Airway hyperresponsiveness (AHR) in children varies by chronic cough cause. Bronchial provocation tests and sputum analysis help diagnose cough causes in children, differentiating conditions like cough variant asthma (CVA).
Area of Science:
- Pediatric Respirology
- Allergy and Immunology
- Diagnostic Medicine
Background:
- Chronic cough is a common pediatric complaint with diverse underlying causes.
- Characterizing airway hyperresponsiveness (AHR) is crucial for accurate diagnosis and management of pediatric chronic cough.
- Distinguishing between cough variant asthma (CVA), upper airway cough syndrome (UACS), and post-infectious cough (PIC) can be challenging.
Purpose of the Study:
- To investigate and compare the characteristics of airway hyperresponsiveness in children presenting with chronic cough attributed to distinct etiologies.
- To evaluate the diagnostic utility of bronchial provocation tests and induced sputum analysis in identifying the specific cause of chronic cough in pediatric patients.
Main Methods:
- A prospective study involving 66 children with single-cause chronic cough.
- Assessment included bronchial provocation tests (measuring PD20 FEV1), induced sputum eosinophil counts, and fractional exhaled nitric oxide (FeNO) at baseline and 4 weeks.
- Final diagnosis was confirmed based on treatment response, clinical examination, and laboratory findings.
Main Results:
- Cough variant asthma (CVA) cases showed significantly lower PD20 values compared to upper airway cough syndrome (UACS) and post-infectious cough (PIC) groups (P < 0.01).
- Sputum eosinophil counts were elevated (>3%) in all CVA cases, whereas UACS and PIC cases had counts below 3%.
- Positive airway hyperresponsiveness (AHR) decreased over 4 weeks in UACS and PIC groups, but remained positive in all CVA cases.
Conclusions:
- Airway hyperresponsiveness characteristics differ based on the etiology of chronic cough in children.
- Combining bronchial provocation tests with induced sputum analysis provides valuable insights for confirming the specific cause of chronic cough in pediatric patients.
- These diagnostic tools aid in differentiating between CVA, UACS, and PIC, guiding appropriate therapeutic strategies.
Objective:
To study the characteristics of airway hyperresponsiveness in children with different causes of chronic cough.
Methods:
A prospective study was conducted in children suffering from chronic cough caused by a single reason at the department of respirology of Children's Hospital of Soochow University from April 2012 to December 2013. Bronchial provocation test, induced sputum eosinophil count, and exhale nitric oxide were detected at beginning and 4 weeks later. The severity of the CVA was classified according to the integral dose of histamine which resulted in a 20% (PD20) fall in forced expiratory volume in 1 s (FEV1). All patients received treatment according to the recommended guidelines for chronic cough in children of China. According to the responses to the treatment and the results of physical examinations and laboratory findings, a final diagnosis was confirmed.
Results:
A total of 66 children were enrolled in this study, including cough variant asthma (CVA)in 17, upper airway cough syndrome (UACS) in 37, and post infection cough (PIC) in 12 cases. Positive AHR in CVA, UACS, and PIC groups was found in 17, 13, and 9 cases respectively at the first visit, and after 4 weeks, it was found in 17, 5, and 2 cases respectively. The severity of AHR in CVA, UACS and PIC at beginning and after 4 weeks were moderate to severe in 5, 0, 0 cases and 1, 0, 0 case; Mild to very mild in 12, 13, 9 cases and 16, 5, 2 cases.Negative response was found in 0, 24, 3 cases and 0, 32, 10 cases, respectively. The values of PD20 in CVA group (0.47 ± 0.28) mg were statistically lower those in UACS group (1.8 ± 0.64) mg and PIC group (1.2 ± 0.80) mg (P < 0.01) . The sputum eosinophil count was > 3% in all cases of CVA but all <3% in UACS and PIC.FeNO and sputum eosinophil counts were positively correlated (r = 0.687, P = 0.000) .
Conclusion:
The characteristics of airway responsiveness of chronic cough caused by different causes were varied in different AHR severity and course. Bronchial provocation test combined with induced sputum showed certain values for confirming the cause of chronic cough in children.
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