Effects of Tiotropium and Salmeterol/Fluticasone Propionate on Airway Wall Thickness in Chronic Obstructive Pulmonary Disease

Abstract

Background: Triple inhalation therapy with tiotropium (Tio) and salmeterol/fluticasone propionate combination (SFC) is widely used in the treatment of chronic obstructive pulmonary disease (COPD). However, the effects of triple therapy on airway structural changes remain unknown. Objective: The aim of the study was to assess the effects of Tio, salmeterol (SM), SFC and Tio plus SFC on airway dimensions in COPD. Methods: A randomized, open-label, 4-way study (n = 60) was conducted comparing 16-week treatment periods of Tio (18 μg once daily), SM (50 μg twice daily), SFC (50/250 μg twice daily) and Tio (18 μg once daily) plus SFC (50/250 μg twice daily). Airway dimensions were assessed by a validated CT technique, and airway wall area (WA) corrected for body surface area (BSA), percentage WA (WA%), wall thickness/√BSA and luminal area (Ai)/BSA at the right apical segmental bronchus were measured. Pulmonary function and the St. George's Respiratory Questionnaire (SGRQ) were evaluated. Results: Tio plus SFC resulted in a significant decrease in WA corrected for BSA and WA% compared with Tio, SM and SFC (p < 0.05 for all). The changes in WA% and Ai/BSA were significantly correlated with changes in forced expiratory volume in 1 s (r = -0.86, p < 0.001, and r = 0.48, p < 0.05, respectively). There were more significant improvements in SGRQ scores after treatment with triple therapy than after the 3 other treatments. Conclusions: Tio plus SFC therapy is more effective than Tio, SM and SFC for reducing airway wall thickness in COPD.