Comparison of airway dimensions with once daily tiotropium plus indacaterol versus twice daily Advair(®) in chronic obstructive pulmonary disease

Abstract

Background: Current guidelines recommend combining long-acting bronchodilators with different modes of action in patients with moderate-to-severe chronic obstructive pulmonary disease (COPD). We evaluated the effects of airway dimensions and pulmonary function with tiotropium plus indacaterol versus Advair(®).

Methods: Subjects (n = 46) were randomized to receive tiotropium (18 μg once daily) plus indacaterol (150 μg once daily) or Advair(®) (50/250 μg twice daily) for 16 weeks. Airway geometry was determined by quantitative computed tomography (luminal area, Ai; total area of the airway, Ao; wall area, WA; and percentage wall area, WA/Ao and wall thickness, T). Spirometry (forced expiratory volume in 1 s, FEV1; forced vital capacity, FVC and inspiratory capacity, IC) and St. George's Respiratory Questionnaire (SGRQ) were evaluated.

Results: Tiotropium plus indacaterol significantly increased CT-indices including Ai corrected for body surface area (Ai/BSA), and decreased WA/BSA, WA/Ao and T/√BSA compared with Advair(®) (p < 0.05, respectively). In physiological parameters, mean difference in IC was significantly higher under treatment with tiotropium plus indacaterol than Advair(®) (p < 0.05). The changes in Ai/BSA, WA/BSA, WA/Ao and T/√BSA were significantly correlated with changes in IC (r = 0.535, p = 0.011; r = -0.688, p < 0.001; r = -0.555, p = 0.002 and r = -0.542, p = 0.007; respectively). There were more significant improvements in SGRQ scores after treatment with tiotropium plus indacaterol than Advair(®).

Conclusions: These findings suggest that dual bronchodilation with tiotropium plus indacaterol is superior in airway geometry and lung function compared with Advair(®) in COPD.

Keywords: Airway geometry; Long-acting muscarinic receptor antagonist; Long-acting β(2)-adrenergic receptor agonist; Pulmonary function; Pulmonary hyperinflation; Quantitative computed tomography.