title: Hydrogen peroxide in exhaled breath condensate in patients with asthma: a promising biomarker?
abstract: BACKGROUND
  The measurement of hydrogen peroxide (H(2)O(2)) in exhaled breath condensate (EBC) has been proposed as a noninvasive way of monitoring airway inflammation. However, results from individual studies on EBC H(2)O(2) evaluation of asthma are conflicting. The purpose of this study was to explore whether EBC H(2)O(2) is elevated in people with asthma and whether it reflects disease severity and disease control or responds to corticosteroid treatment.
  
  
  METHODS
  Studies were identified by searching PubMed, Embase, Cochrane Database, Cumulative Index to Nursing and Allied Health Literature (CINAHL), and www.controlled-trials.com for relevant reports published before September 2010. Observational studies comparing levels of EBC H(2)O(2) between patients with asthma who were nonsmokers and healthy subjects were included. Data were independently extracted by two investigators and analyzed using Stata 10.0 software.
  
  
  RESULTS
  Eight studies (involving 728 participants) were included. EBC H(2)O(2) concentrations were significantly higher in patients with asthma who were nonsmokers compared with healthy subjects, and higher values of EBC H(2)O(2) were observed at each level of asthma, classified either by severity or control level, and the values were negatively correlated with FEV(1). In addition, EBC H(2)O(2) concentrations were lower in patients with asthma treated with corticosteroids than in patients with asthma not treated with corticosteroids.
  
  
  CONCLUSIONS
  H(2)O(2) might be a promising biomarker for guiding asthma treatment. However, further investigation is needed to establish its role.
authors: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors: Yue
authors: Y
authors: Teng
authors: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors: Peili
authors: P
authors: Sun
authors: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors: Jingying
authors: J
authors: Zhang
authors: Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.
authors: Rongbin
authors: R
authors: Yu
authors: Department of Epidemiology and Biostatistics, School of Public Health, Nanjing Medical University, Nanjing, China.
authors: Jianling
authors: J
authors: Bai
authors: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China. Electronic address: yaoxin@njmu.edu.cn.
authors: Xin
authors: X
authors: Yao
authors: Department of Respiratory Medicine, The First Affiliated Hospital of Nanjing Medical University, Nanjing, China.
authors: Mao
authors: M
authors: Huang
authors: Airway Disease Section, National Heart and Lung Institute, Imperial College, London, England.
authors: Ian M
authors: IM
authors: Adcock
authors: Airway Disease Section, National Heart and Lung Institute, Imperial College, London, England.
authors: Peter J
authors: PJ
authors: Barnes
mesh_terms: D001249:Asthma / Q000175:diagnosis / Q000378:metabolism*; D015415:Biomarkers / Q000032:analysis*; D001944:Breath Tests / Q000379:methods*; D045853:Exhalation; D006801:Humans; D006861:Hydrogen Peroxide / Q000032:analysis*; D012720:Severity of Illness Index
chemical_list: D015415:Biomarkers; D006861:Hydrogen Peroxide