title: [Study on dynamic changes of airway hyperresponsiveness in children with cough variant asthma].
abstract: OBJECTIVE
  To explore the dynamic changes of airway hyperresponsiveness (AHR) in children with cough variant asthma (CVA).
  
  
  METHODS
  A prospective observational study was conducted at the Children's Hospital of Soochow University from April 2012 to March 2013. A total of 36 patients were diagnosed as CVA. According to the integral dose of histamine resulting in a 20% (PD20) fall in forced expiratory volume in 1 s (FEV1), the severity of CVA was graded. Corresponding treatment was administered and the dynamic changes of airway hyperresponsiveness were followed for 0, 1 and 6 months.
  
  
  RESULTS
  Among them, 14 patients suffered from CVA only while another 22 cases had CVA plus upper airway cough syndrome (UACS). PD20 of CVA and CVA+UACS groups were (0.46 ± 0.26) and (0.58 ± 0.34) mg respectively. No statistically significance existed between two groups (t = -0.880, P > 0.05). According to the value of PD20, AHR in CVA patients was classified into four degrees of severe, moderate, mild and very mild. Initially there were moderate (n = 8), mild (n = 21) and very mild (n = 5). At 1 month follow-up, moderate (n = 1), mild (n = 28) and borderline (n = 7); At 6 month, moderate (n = 2), mild (n = 20) and very mild (n = 7). And 4 cases turned negative and another 3 cases became lost. Cough symptom score and PD20 showed no significant correlation (r = -0.086, P > 0.05).
  
  
  CONCLUSIONS
  AHR in CVA patients is predominantly mild and very mild. And it decreases rapidly mostly during initial treatment phase. The proportion of conversion from CVA into negative and typical bronchial asthma is relatively low.
authors.affiliation: Department of Respiratory Diseases, Children's Hospital of Soochow University, Suzhou 215003, China.
authors.forename: Xingmei
authors.initials: X
authors.lastname: Yu
authors.forename: Haiyan
authors.initials: H
authors.lastname: Zhu
authors.forename: Xiaoyun
authors.initials: X
authors.lastname: Yang
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Lu
authors.forename: Huiquan
authors.initials: H
authors.lastname: Sun
authors.forename: Liping
authors.initials: L
authors.lastname: Fan
authors.forename: Hui
authors.initials: H
authors.lastname: Tao
authors.forename: Jing
authors.initials: J
authors.lastname: Zhou
authors.forename: Wei
authors.initials: W
authors.lastname: Luo
authors.forename: Kefang
authors.initials: K
authors.lastname: Lai
authors.affiliation: Email: hcl_md@163.com.
authors.forename: Chuangli
authors.initials: C
authors.lastname: Hao
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000150:complications / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000503:physiopathology*; D002648:Child; D003371:Cough / Q000209:etiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011446:Prospective Studies