The measurement of hydrogen peroxide (H2O2) in exhaled breath condensate (EBC) has been proposed as a noninvasive way of monitoring airway inflammation. However, results from individual studies on EBC H2O2 evaluation of asthma are conflicting. The purpose of this study was to explore whether EBC H2O2 is elevated in people with asthma and whether it reflects disease severity and disease control or responds to corticosteroid treatment.
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 H2O2 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.
Eight studies (involving 728 participants) were included. EBC H2O2 concentrations were significantly higher in patients with asthma who were nonsmokers compared with healthy subjects, and higher values of EBC H2O2 were observed at each level of asthma, classified either by severity or control level, and the values were negatively correlated with FEV1. In addition, EBC H2O2 concentrations were lower in patients with asthma treated with corticosteroids than in patients with asthma not treated with corticosteroids.
H2O2 might be a promising biomarker for guiding asthma treatment. However, further investigation is needed to establish its role.