Inhaled corticosteroids improve lung function, airway hyper-responsiveness and airway inflammation but not symptom control in patients with mild intermittent asthma: A meta-analysis

It remains controversial whether inhaled corticosteroid (ICS) should be used in patients with intermittent asthma. The present study aimed to assess the effect of ICS compared with placebo or other therapies in patients with intermittent asthma. Medline, Embase and CNKI databases were searched up to June 2016 and a meta-analysis was conducted. The findings demonstrated that in adult patients, when compared with placebo, ICS increased forced expiratory volume in 1 sec FEV1 [standardized mean difference (SMD), 0.51; 95% confidence interval (CI), 0.22-0.80] and alleviated airway hyper-responsiveness, which was indicated as log transformed PC20FEV1 (concentrations of methacholine when there was a fall in FEV1 >= 20%; SMD, 0.87; 95% CI, 0.60 to 1.14). ICS also reduced fractional exhaled nitric oxide (FeNO) levels [weighted mean difference (WMD), -12.57 parts per billion (ppb; a unit of NO concentration in exhaled air); 95% CI -15.88 to -9.25 ppb]. However, symptom scores did not change after ICS treatment (SMD, -0.26; 95% CI, -0.52 to 0). When compared with leukotriene receptor antagonists (LTRA), ICS had no advantage in increasing FEV1 (WMD, 0.04 l; 95% CI, -0.06 to 0.13 l), reducing sputum eosinophil percentage (WMD, -6%; 95% CI, -12.38 to 0.38%) or symptom scores (SMD, 0.44; 95% CI, -0.02 to 0.9). However, in child patients, ICS significantly (P< 0.05) increased the possibility of symptom control when compared with placebo [relative risk (RR), 8; 95% CI, 1.04 to 61.52] or LTRA (RR, 2.67; 95% CI, 0.39 to 18.42). In conclusion, ICS improves lung function and alleviates airway hyper-responsiveness and airway inflammation but cannot influence symptom scores, and has no advantage over LTRA in terms of lung function improvement and airway inflammation control in adult patients with mild intermittent asthma. However, in children, the benefit of ICS in symptom control is more significant than with LTRA.