Smoking influences response to inhaled corticosteroids in patients with asthma: a meta-analysis

AbstractObjective:To determine the effects of smoking on efficacy of inhaled corticosteroids in asthmatics.Research design and methods:Prospective/retrospective, controlled studies published up to May 2012 in smokers versus non-smokers with asthma using inhaled corticosteroids (ICSs) were retrieved from PubMed, Highwire and Embase databases.Main outcome measures:The primary outcomes were pulmonary function parameters [FEV1 (forced expiratory volume in 1 second), a.m. PEF (a.m. peak expiratory flow) and p.m. PEF (p.m. peak expiratory flow)]. Secondary outcomes included differential eosinophil counts in sputum and peripheral blood, asthma control questionnaire-5 (ACQ-5) and concomitant use of medication. Pooled SMDs (standardized mean differences) were estimated by using a random-effect model and a fixed-effect model based on between-study heterogeneity.Results:Of 242 studies identified, ten (N = 4070) met the inclusion criteria (seven of budesonide-based interventions, two of fluticasone and one unknown IC...