Effect of inhaled corticosteroid particle size on asthma efficacy and safety outcomes: a systematic literature review and meta-analysis

Background: Inhaled corticosteroids (ICS) are the primary treatment for persistent asthma. Currently available ICS have differing particle size due to both formulation and propellant, and it has been postulated that this may impact patient outcomes. This structured literature review and meta-analysis compared the effect of small and standard particle size ICS on lung function, symptoms, rescue use (when available) and safety in patients with asthma as assessed in head-to-head randomized controlled trials (RCTs). Methods: A systematic literature search of MEDLINE was performed to identify RCTs (1998-2014) evaluating standard size (fluticasone propionate-containing medications) versus small particle size ICS medication in adults and children with asthma. Efficacy outcomes included forced expiratory volume in 1 s (FEV1), morning peak expiratory flow (PEF), symptom scores, % predicted forced expiratory flow between 25 and 75% of forced vital capacity (FEF25-75%), and rescue medication use. Safety outcomes were also evaluated when available. Results: Twenty-three independent trials that met the eligibility criteria were identified. Benefit-risk plots did not demonstrate any clinically meaningful differences across the five efficacy endpoints considered and no appreciable differences were noted for most safety endpoints. Meta-analysis results, using a random-effects model, demonstrated no significant difference between standard and small size particle ICS medications in terms of effects on mean change from baseline FEV1 (L) (-0.011, 95% confidence interval [CI]: -0.037, 0.014 [N = 3524]), morning PEF (L/min) (medium/low doses: -3.874, 95% CI: -10.915, 3.166 [N = 1911]; high/high-medium doses: 5.551, 95% CI: -1.948, 13.049 [N = 749]) and FEF25-75% predicted (-2.418, 95% CI: -6.400; 1.564 [N = 115]). Conclusions: Based on the available literature, no clinically significant differences in efficacy or safety were observed comparing small and standard particle size ICS medications for the treatment of asthma.