Exhaled H2O2 in steady-state bronchiectasis - Relationship with cellular composition in induced sputum, spirometry, and extent and severity of disease

Study objectives: To determine the concentration of exhaled H2O2 in patients with bronchiectasis, and to study the relationship between levels of exhaled H2O2 extent of disease, symptoms score, spirometry, and cellular composition obtained from induced sputum; furthermore, to account for possible confounding effects of inhaled corticosteroids (ICS) usage, long-term oral antibiotic treatment, and chronic colonization with Pseudomonas aeruginosa. Design: Cross-sectional study. Patients: Thirty patients with steady-state bronchiectasis. Results: Mean (95% confidence interval [CI]) exhaled H2O2 levels were significantly elevated in patients with bronchiectasis compared to normal subjects: 1.1 (0.87 to 1.29) muM vs 0.3 (0.19 to 0.36) muM, respectively (p < 0.0001). Patients treated with ICS had similar values as steroid-naive patients. The group of patients with P aeruginosa colonization showed a significantly increased concentration of H2O2 compared to the group without P aeruginosa colonization. Patients receiving long-term oral antibiotic treatment had significantly higher values of H2O2 compared to those not receiving antibiotics. There was a significant positive correlation between H2O2 and either the percentage of neutrophils in induced sputum or the extent of the disease as defined by high-resolution CT. A significant negative correlation was found between H2O2 and FEV1, percent predicted. Finally, there was a significant positive correlation between H2O2 and the symptoms score. Conclusions: Patients with bronchiectasis in stable condition showed increased levels of exhaled H2O2. The above-mentioned levels were not decreased either by ICS or long-term oral antibiotic treatment, but were significantly affected by chronic colonization with P aeruginosa. H2O2 levels could be an indirect index of neutrophilic inflammation, impairment of lung function, and extension and severity of the disease.