Clinically masked increases in bronchial inflammation in guideline-treated persistent asthma

BACKGROUND: Current guidelines generally recommend a combination of inhaled corticosteroids and a Beta2-agonist for persistent asthma. The adjustment of anti-inflammatory therapy in persistent asthma is advised to be guided mainly by the presence of symptoms. OBJECTIVE: To investigate whether clinically masked increases in bronchial inflammation occur in guideline-treated, persistent asthma following allergen exposure. METHODS: After a 4-week steroid-run-in period (fluticasone 250 microg twice daily) 48 allergic patients with persistent asthma underwent a bronchial challenge with a single dose of allergen, after inhalation of salbutamol (400 microg, nebulized dose). FEV1 and sputum markers of bronchial inflammation were measured before and after allergen challenge. Furthermore, additional rescue-salbutamol usage was recorded following allergen challenge. RESULTS: After allergen challenge there was a significant increase in sputum eosinophil numbers (geometric mean number x 10(4)/g [95% CI]: 0.5 [0.3; 1.0] before, and 2.4 [1.3; 4.2] after challenge, p=0.01). The mean change in FEV1 between 4 and 8h after challenge relative to baseline was -0.04% [95% CI-2.3; 2.2], p>0.9. None of the patients took additional rescue salbutamol over 8 h after allergen challenge. CONCLUSIONS: Clinically masked increases in bronchial inflammation occur in guideline-treated, persistent asthma following allergen exposure. This finding underscores the need for additional guides for the adjustment of anti-inflammatory therapy in persistent asthma