title: 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. Asthma and Allergy Group.
abstract: 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 (> or = 2000 micrograms 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 < 0.002), but lower than levels in steroid naive mild asthmatics (36.9 ppb, 95% CI 34.6 to 39.3; p < 0.001). Prednisolone treated patients had higher exhaled NO levels than patients only requiring inhaled corticosteroids (17.5 ppb, 95% CI 11.1 to 24.0 versus 7.2 ppb, 95% CI 4.6 to 9.8; p = 0.016), suggesting greater disease severity in this group. Non-compliance with prednisolone treatment was observed in 20% of patients but this did not explain the difference between the treatment groups. Exhaled NO levels were closely correlated with symptom frequency (p = 0.03) and with rescue beta agonist use (p < 0.002), but they did not correlate with lung function.
  
  
  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.
authors: Royal Brompton Hospital, London, UK.
authors: R G
authors: RG
authors: Stirling
authors: S A
authors: SA
authors: Kharitonov
authors: D
authors: D
authors: Campbell
authors: D S
authors: DS
authors: Robinson
authors: S R
authors: SR
authors: Durham
authors: K F
authors: KF
authors: Chung
authors: P J
authors: PJ
authors: Barnes
mesh_terms: D000280:Administration, Inhalation; D000284:Administration, Oral; D000293:Adolescent; D000328:Adult; D000368:Aged; D000893:Anti-Inflammatory Agents / Q000627:therapeutic use*; D001249:Asthma / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology; D015415:Biomarkers; D001944:Breath Tests; D005260:Female; D005938:Glucocorticoids / Q000627:therapeutic use*; D006801:Humans; D008168:Lung / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000378:metabolism*; D010349:Patient Compliance; D011239:Prednisolone / Q000097:blood
chemical_list: D000893:Anti-Inflammatory Agents; D015415:Biomarkers; D005938:Glucocorticoids; D009569:Nitric Oxide; D011239:Prednisolone