Objective: A proportion of asthmatic patients can achieve total control according to the Global Initiative for Asthma/National Institute of Health guidelines. The aim of this study was to investigate whether total control of asthma is accompanied by the remission of airway inflammation and bronchial hyperresponsiveness.
Methods: We assessed the number of eosinophil and the levels of eosinophil cationic protein (ECP) and interleukin (IL)-5 in induced sputum and bronchial responsiveness to methacholine in 76 patients with totally controlled asthma in comparison with 30 current untreated asthmatics and 20 healthy subjects.
Results: We found significantly higher number of eosinophil and higher levels of ECP and IL-5 in the total control group than those in healthy subjects (6.9% +/- 3.6% and 1.3% +/- 1.1%, 129.0 +/- 53.8 mug/l and 48.9 +/- 20.4 mug/l, 22.1 +/- 15.2 mug/l and 10.6 +/- 5.2 mug/l, respectively; p < 0.001), but lower than those in current asthma group (16.2% +/- 8.6%, 362.2 +/- 151.6 mug/l, 50.6 +/-25.8 mug/l, respectively; p < 0.001). Sixty-five (85.5%) patients with totally controlled asthma showed positive methacholine challenge test. In the total control group, number of eosinophil and the levels of ECP and IL-5 in induced sputum of patients with negative methacholine challenge test were significantly lower than those in subjects with positive methacholine challenge test (p < 0.001), whereas sputum number of eosinophil and the levels of ECP and IL-5 in patients with negative methacholine challenge test and those of healthy subjects were similar (p > 0.05).
Conclusion: The results of this study suggest that airway inflammation and bronchial hyperresponsiveness still persisted during total control of asthma.