Increase in exhaled nitric oxide levels in patients with difficult asthma and correlation with symptoms and disease severity despite treatment with oral and inhaled corticosteroids

BACKGROUND Patients with difficult asthma suffer chronic moderate to severe persistent asthma symptoms despite high doses of inhaled and oral corticosteroid therapy. These patients suffer a high level of treatment and disease related morbidity but little is known about the degree of airway inflammation in these patients. METHODS Fifty two patients were examined to assess levels of exhaled nitric oxide (NO) as a surrogate marker of inflammatory activity in this condition. From this group, 26 patients were defined with severe symptoms and current physiological evidence of reversible airway obstruction requiring high dose inhaled (⩾2000 μg beclomethasone dipropionate (BDP) equivalent) or oral steroid therapy to maintain disease control. RESULTS Exhaled NO levels were higher in subjects with difficult asthma (mean 13.9 ppb, 95% CI 9.3 to 18.5) than in normal controls (7.4 ppb, 95% CI 6.9 to 7.8; p CONCLUSIONS Exhaled NO may serve as a useful complement to lung function and symptomatology in the assessment of patients with chronic severe asthma, and in the control and rationalisation of steroid therapy in these patients.